nbtreadpage.c File Reference

#include "postgres.h"
#include "access/nbtree.h"
#include "access/relscan.h"
#include "storage/predicate.h"
#include "utils/datum.h"
#include "utils/rel.h"

Include dependency graph for nbtreadpage.c:

Go to the source code of this file.

Data Structures
struct	BTReadPageState

Macros
#define	LOOK_AHEAD_REQUIRED_RECHECKS   3
#define	LOOK_AHEAD_DEFAULT_DISTANCE   5
#define	NSKIPADVANCES_THRESHOLD   3

Typedefs
typedef struct BTReadPageState	BTReadPageState

Functions
static void	_bt_set_startikey (IndexScanDesc scan, BTReadPageState *pstate)
static bool	_bt_scanbehind_checkkeys (IndexScanDesc scan, ScanDirection dir, IndexTuple finaltup)
static bool	_bt_oppodir_checkkeys (IndexScanDesc scan, ScanDirection dir, IndexTuple finaltup)
static void	_bt_saveitem (BTScanOpaque so, int itemIndex, OffsetNumber offnum, IndexTuple itup)
static int	_bt_setuppostingitems (BTScanOpaque so, int itemIndex, OffsetNumber offnum, const ItemPointerData *heapTid, IndexTuple itup)
static void	_bt_savepostingitem (BTScanOpaque so, int itemIndex, OffsetNumber offnum, ItemPointer heapTid, int tupleOffset)
static bool	_bt_checkkeys (IndexScanDesc scan, BTReadPageState *pstate, bool arrayKeys, IndexTuple tuple, int tupnatts)
static bool	_bt_check_compare (IndexScanDesc scan, ScanDirection dir, IndexTuple tuple, int tupnatts, TupleDesc tupdesc, bool advancenonrequired, bool forcenonrequired, bool *continuescan, int *ikey)
static bool	_bt_check_rowcompare (ScanKey header, IndexTuple tuple, int tupnatts, TupleDesc tupdesc, ScanDirection dir, bool forcenonrequired, bool *continuescan)
static bool	_bt_rowcompare_cmpresult (ScanKey subkey, int cmpresult)
static bool	_bt_tuple_before_array_skeys (IndexScanDesc scan, ScanDirection dir, IndexTuple tuple, TupleDesc tupdesc, int tupnatts, bool readpagetup, int sktrig, bool *scanBehind)
static void	_bt_checkkeys_look_ahead (IndexScanDesc scan, BTReadPageState *pstate, int tupnatts, TupleDesc tupdesc)
static bool	_bt_advance_array_keys (IndexScanDesc scan, BTReadPageState *pstate, IndexTuple tuple, int tupnatts, TupleDesc tupdesc, int sktrig, bool sktrig_required)
static bool	_bt_advance_array_keys_increment (IndexScanDesc scan, ScanDirection dir, bool *skip_array_set)
static bool	_bt_array_increment (Relation rel, ScanKey skey, BTArrayKeyInfo *array)
static bool	_bt_array_decrement (Relation rel, ScanKey skey, BTArrayKeyInfo *array)
static void	_bt_array_set_low_or_high (Relation rel, ScanKey skey, BTArrayKeyInfo *array, bool low_not_high)
static void	_bt_skiparray_set_element (Relation rel, ScanKey skey, BTArrayKeyInfo *array, int32 set_elem_result, Datum tupdatum, bool tupnull)
static void	_bt_skiparray_set_isnull (Relation rel, ScanKey skey, BTArrayKeyInfo *array)
static int32	_bt_compare_array_skey (FmgrInfo *orderproc, Datum tupdatum, bool tupnull, Datum arrdatum, ScanKey cur)
static void	_bt_binsrch_skiparray_skey (bool cur_elem_trig, ScanDirection dir, Datum tupdatum, bool tupnull, BTArrayKeyInfo *array, ScanKey cur, int32 *set_elem_result)
bool	_bt_readpage (IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum, bool firstpage)
void	_bt_start_array_keys (IndexScanDesc scan, ScanDirection dir)
int	_bt_binsrch_array_skey (FmgrInfo *orderproc, bool cur_elem_trig, ScanDirection dir, Datum tupdatum, bool tupnull, BTArrayKeyInfo *array, ScanKey cur, int32 *set_elem_result)

Macro Definition Documentation

LOOK_AHEAD_DEFAULT_DISTANCE

#define LOOK_AHEAD_DEFAULT_DISTANCE   5

Definition at line 1117 of file nbtreadpage.c.

LOOK_AHEAD_REQUIRED_RECHECKS

#define LOOK_AHEAD_REQUIRED_RECHECKS   3

Definition at line 1116 of file nbtreadpage.c.

NSKIPADVANCES_THRESHOLD

#define NSKIPADVANCES_THRESHOLD   3

Definition at line 1118 of file nbtreadpage.c.

Typedef Documentation

BTReadPageState

typedef struct BTReadPageState BTReadPageState

Function Documentation

_bt_advance_array_keys()

static bool _bt_advance_array_keys ( IndexScanDesc  scan, BTReadPageState *  pstate, IndexTuple  tuple, int  tupnatts, TupleDesc  tupdesc, int  sktrig, bool  sktrig_required  )

static

Definition at line 2182 of file nbtreadpage.c.

{
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
    Relation    rel = scan->indexRelation;
    ScanDirection dir = pstate ? pstate->dir : ForwardScanDirection;
    int         arrayidx = 0;
    bool        beyond_end_advance = false,
                skip_array_advanced = false,
                has_required_opposite_direction_only = false,
                all_required_satisfied = true,
                all_satisfied = true;
 
    Assert(!so->needPrimScan && !so->scanBehind && !so->oppositeDirCheck);
    Assert(_bt_verify_keys_with_arraykeys(scan));
 
    if (sktrig_required)
    {
        /*
         * Precondition array state assertion
         */
        Assert(!_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc,
                                             tupnatts, false, 0, NULL));
 
        /*
         * Once we return we'll have a new set of required array keys, so
         * reset state used by "look ahead" optimization
         */
        pstate->rechecks = 0;
        pstate->targetdistance = 0;
    }
    else if (sktrig < so->numberOfKeys - 1 &&
             !(so->keyData[so->numberOfKeys - 1].sk_flags & SK_SEARCHARRAY))
    {
        int         least_sign_ikey = so->numberOfKeys - 1;
        bool        continuescan;
 
        /*
         * Optimization: perform a precheck of the least significant key
         * during !sktrig_required calls when it isn't already our sktrig
         * (provided the precheck key is not itself an array).
         *
         * When the precheck works out we'll avoid an expensive binary search
         * of sktrig's array (plus any other arrays before least_sign_ikey).
         */
        Assert(so->keyData[sktrig].sk_flags & SK_SEARCHARRAY);
        if (!_bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
                               false, &continuescan,
                               &least_sign_ikey))
            return false;
    }
 
    for (int ikey = 0; ikey < so->numberOfKeys; ikey++)
    {
        ScanKey     cur = so->keyData + ikey;
        BTArrayKeyInfo *array = NULL;
        Datum       tupdatum;
        bool        required = false,
                    tupnull;
        int32       result;
        int         set_elem = 0;
 
        if (cur->sk_strategy == BTEqualStrategyNumber)
        {
            /* Manage array state */
            if (cur->sk_flags & SK_SEARCHARRAY)
            {
                array = &so->arrayKeys[arrayidx++];
                Assert(array->scan_key == ikey);
            }
        }
        else
        {
            /*
             * Are any inequalities required in the opposite direction only
             * present here?
             */
            if (((ScanDirectionIsForward(dir) &&
                  (cur->sk_flags & (SK_BT_REQBKWD))) ||
                 (ScanDirectionIsBackward(dir) &&
                  (cur->sk_flags & (SK_BT_REQFWD)))))
                has_required_opposite_direction_only = true;
        }
 
        /* Optimization: skip over known-satisfied scan keys */
        if (ikey < sktrig)
            continue;
 
        if (cur->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD))
        {
            required = true;
 
            if (cur->sk_attno > tupnatts)
            {
                /* Set this just like _bt_tuple_before_array_skeys */
                Assert(sktrig < ikey);
                so->scanBehind = true;
            }
        }
 
        /*
         * Handle a required non-array scan key that the initial call to
         * _bt_check_compare indicated triggered array advancement, if any.
         *
         * The non-array scan key's strategy will be <, <=, or = during a
         * forwards scan (or any one of =, >=, or > during a backwards scan).
         * It follows that the corresponding tuple attribute's value must now
         * be either > or >= the scan key value (for backwards scans it must
         * be either < or <= that value).
         *
         * If this is a required equality strategy scan key, this is just an
         * optimization; _bt_tuple_before_array_skeys already confirmed that
         * this scan key places us ahead of caller's tuple.  There's no need
         * to repeat that work now.  (The same underlying principle also gets
         * applied by the cur_elem_trig optimization used to speed up searches
         * for the next array element.)
         *
         * If this is a required inequality strategy scan key, we _must_ rely
         * on _bt_check_compare like this; we aren't capable of directly
         * evaluating required inequality strategy scan keys here, on our own.
         */
        if (ikey == sktrig && !array)
        {
            Assert(sktrig_required && required && all_required_satisfied);
 
            /* Use "beyond end" advancement.  See below for an explanation. */
            beyond_end_advance = true;
            all_satisfied = all_required_satisfied = false;
 
            continue;
        }
 
        /*
         * Nothing more for us to do with an inequality strategy scan key that
         * wasn't the one that _bt_check_compare stopped on, though.
         *
         * Note: if our later call to _bt_check_compare (to recheck caller's
         * tuple) sets continuescan=false due to finding this same inequality
         * unsatisfied (possible when it's required in the scan direction),
         * we'll deal with it via a recursive "second pass" call.
         */
        else if (cur->sk_strategy != BTEqualStrategyNumber)
            continue;
 
        /*
         * Nothing for us to do with an equality strategy scan key that isn't
         * marked required, either -- unless it's a non-required array
         */
        else if (!required && !array)
            continue;
 
        /*
         * Here we perform steps for all array scan keys after a required
         * array scan key whose binary search triggered "beyond end of array
         * element" array advancement due to encountering a tuple attribute
         * value > the closest matching array key (or < for backwards scans).
         */
        if (beyond_end_advance)
        {
            if (array)
                _bt_array_set_low_or_high(rel, cur, array,
                                          ScanDirectionIsBackward(dir));
 
            continue;
        }
 
        /*
         * Here we perform steps for all array scan keys after a required
         * array scan key whose tuple attribute was < the closest matching
         * array key when we dealt with it (or > for backwards scans).
         *
         * This earlier required array key already puts us ahead of caller's
         * tuple in the key space (for the current scan direction).  We must
         * make sure that subsequent lower-order array keys do not put us too
         * far ahead (ahead of tuples that have yet to be seen by our caller).
         * For example, when a tuple "(a, b) = (42, 5)" advances the array
         * keys on "a" from 40 to 45, we must also set "b" to whatever the
         * first array element for "b" is.  It would be wrong to allow "b" to
         * be set based on the tuple value.
         *
         * Perform the same steps with truncated high key attributes.  You can
         * think of this as a "binary search" for the element closest to the
         * value -inf.  Again, the arrays must never get ahead of the scan.
         */
        if (!all_required_satisfied || cur->sk_attno > tupnatts)
        {
            if (array)
                _bt_array_set_low_or_high(rel, cur, array,
                                          ScanDirectionIsForward(dir));
 
            continue;
        }
 
        /*
         * Search in scankey's array for the corresponding tuple attribute
         * value from caller's tuple
         */
        tupdatum = index_getattr(tuple, cur->sk_attno, tupdesc, &tupnull);
 
        if (array)
        {
            bool        cur_elem_trig = (sktrig_required && ikey == sktrig);
 
            /*
             * "Binary search" by checking if tupdatum/tupnull are within the
             * range of the skip array
             */
            if (array->num_elems == -1)
                _bt_binsrch_skiparray_skey(cur_elem_trig, dir,
                                           tupdatum, tupnull, array, cur,
                                           &result);
 
            /*
             * Binary search for the closest match from the SAOP array
             */
            else
                set_elem = _bt_binsrch_array_skey(&so->orderProcs[ikey],
                                                  cur_elem_trig, dir,
                                                  tupdatum, tupnull, array, cur,
                                                  &result);
        }
        else
        {
            Assert(required);
 
            /*
             * This is a required non-array equality strategy scan key, which
             * we'll treat as a degenerate single element array.
             *
             * This scan key's imaginary "array" can't really advance, but it
             * can still roll over like any other array.  (Actually, this is
             * no different to real single value arrays, which never advance
             * without rolling over -- they can never truly advance, either.)
             */
            result = _bt_compare_array_skey(&so->orderProcs[ikey],
                                            tupdatum, tupnull,
                                            cur->sk_argument, cur);
        }
 
        /*
         * Consider "beyond end of array element" array advancement.
         *
         * When the tuple attribute value is > the closest matching array key
         * (or < in the backwards scan case), we need to ratchet this array
         * forward (backward) by one increment, so that caller's tuple ends up
         * being < final array value instead (or > final array value instead).
         * This process has to work for all of the arrays, not just this one:
         * it must "carry" to higher-order arrays when the set_elem that we
         * just found happens to be the final one for the scan's direction.
         * Incrementing (decrementing) set_elem itself isn't good enough.
         *
         * Our approach is to provisionally use set_elem as if it was an exact
         * match now, then set each later/less significant array to whatever
         * its final element is.  Once outside the loop we'll then "increment
         * this array's set_elem" by calling _bt_advance_array_keys_increment.
         * That way the process rolls over to higher order arrays as needed.
         *
         * Under this scheme any required arrays only ever ratchet forwards
         * (or backwards), and always do so to the maximum possible extent
         * that we can know will be safe without seeing the scan's next tuple.
         * We don't need any special handling for required scan keys that lack
         * a real array to advance, nor for redundant scan keys that couldn't
         * be eliminated by _bt_preprocess_keys.  It won't matter if some of
         * our "true" array scan keys (or even all of them) are non-required.
         */
        if (sktrig_required && required &&
            ((ScanDirectionIsForward(dir) && result > 0) ||
             (ScanDirectionIsBackward(dir) && result < 0)))
            beyond_end_advance = true;
 
        Assert(all_required_satisfied && all_satisfied);
        if (result != 0)
        {
            /*
             * Track whether caller's tuple satisfies our new post-advancement
             * qual, for required scan keys, as well as for the entire set of
             * interesting scan keys (all required scan keys plus non-required
             * array scan keys are considered interesting.)
             */
            all_satisfied = false;
            if (sktrig_required && required)
                all_required_satisfied = false;
            else
            {
                /*
                 * There's no need to advance the arrays using the best
                 * available match for a non-required array.  Give up now.
                 * (Though note that sktrig_required calls still have to do
                 * all the usual post-advancement steps, including the recheck
                 * call to _bt_check_compare.)
                 */
                break;
            }
        }
 
        /* Advance array keys, even when we don't have an exact match */
        if (array)
        {
            if (array->num_elems == -1)
            {
                /* Skip array's new element is tupdatum (or MINVAL/MAXVAL) */
                _bt_skiparray_set_element(rel, cur, array, result,
                                          tupdatum, tupnull);
                skip_array_advanced = true;
            }
            else if (array->cur_elem != set_elem)
            {
                /* SAOP array's new element is set_elem datum */
                array->cur_elem = set_elem;
                cur->sk_argument = array->elem_values[set_elem];
            }
        }
    }
 
    /*
     * Advance the array keys incrementally whenever "beyond end of array
     * element" array advancement happens, so that advancement will carry to
     * higher-order arrays (might exhaust all the scan's arrays instead, which
     * ends the top-level scan).
     */
    if (beyond_end_advance &&
        !_bt_advance_array_keys_increment(scan, dir, &skip_array_advanced))
        goto end_toplevel_scan;
 
    Assert(_bt_verify_keys_with_arraykeys(scan));
 
    /*
     * Maintain a page-level count of the number of times the scan's array
     * keys advanced in a way that affected at least one skip array
     */
    if (sktrig_required && skip_array_advanced)
        pstate->nskipadvances++;
 
    /*
     * Does tuple now satisfy our new qual?  Recheck with _bt_check_compare.
     *
     * Calls triggered by an unsatisfied required scan key, whose tuple now
     * satisfies all required scan keys, but not all nonrequired array keys,
     * will still require a recheck call to _bt_check_compare.  They'll still
     * need its "second pass" handling of required inequality scan keys.
     * (Might have missed a still-unsatisfied required inequality scan key
     * that caller didn't detect as the sktrig scan key during its initial
     * _bt_check_compare call that used the old/original qual.)
     *
     * Calls triggered by an unsatisfied nonrequired array scan key never need
     * "second pass" handling of required inequalities (nor any other handling
     * of any required scan key).  All that matters is whether caller's tuple
     * satisfies the new qual, so it's safe to just skip the _bt_check_compare
     * recheck when we've already determined that it can only return 'false'.
     *
     * Note: In practice most scan keys are marked required by preprocessing,
     * if necessary by generating a preceding skip array.  We nevertheless
     * often handle array keys marked required as if they were nonrequired.
     * This behavior is requested by our _bt_check_compare caller, though only
     * when it is passed "forcenonrequired=true" by _bt_checkkeys.
     */
    if ((sktrig_required && all_required_satisfied) ||
        (!sktrig_required && all_satisfied))
    {
        int         nsktrig = sktrig + 1;
        bool        continuescan;
 
        Assert(all_required_satisfied);
 
        /* Recheck _bt_check_compare on behalf of caller */
        if (_bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
                              !sktrig_required, &continuescan,
                              &nsktrig) &&
            !so->scanBehind)
        {
            /* This tuple satisfies the new qual */
            Assert(all_satisfied && continuescan);
 
            if (pstate)
                pstate->continuescan = true;
 
            return true;
        }
 
        /*
         * Consider "second pass" handling of required inequalities.
         *
         * It's possible that our _bt_check_compare call indicated that the
         * scan should end due to some unsatisfied inequality that wasn't
         * initially recognized as such by us.  Handle this by calling
         * ourselves recursively, this time indicating that the trigger is the
         * inequality that we missed first time around (and using a set of
         * required array/equality keys that are now exact matches for tuple).
         *
         * We make a strong, general guarantee that every _bt_checkkeys call
         * here will advance the array keys to the maximum possible extent
         * that we can know to be safe based on caller's tuple alone.  If we
         * didn't perform this step, then that guarantee wouldn't quite hold.
         */
        if (unlikely(!continuescan))
        {
            bool        satisfied PG_USED_FOR_ASSERTS_ONLY;
 
            Assert(sktrig_required);
            Assert(so->keyData[nsktrig].sk_strategy != BTEqualStrategyNumber);
 
            /*
             * The tuple must use "beyond end" advancement during the
             * recursive call, so we cannot possibly end up back here when
             * recursing.  We'll consume a small, fixed amount of stack space.
             */
            Assert(!beyond_end_advance);
 
            /* Advance the array keys a second time using same tuple */
            satisfied = _bt_advance_array_keys(scan, pstate, tuple, tupnatts,
                                               tupdesc, nsktrig, true);
 
            /* This tuple doesn't satisfy the inequality */
            Assert(!satisfied);
            return false;
        }
 
        /*
         * Some non-required scan key (from new qual) still not satisfied.
         *
         * All scan keys required in the current scan direction must still be
         * satisfied, though, so we can trust all_required_satisfied below.
         */
    }
 
    /*
     * When we were called just to deal with "advancing" non-required arrays,
     * this is as far as we can go (cannot stop the scan for these callers)
     */
    if (!sktrig_required)
    {
        /* Caller's tuple doesn't match any qual */
        return false;
    }
 
    /*
     * Postcondition array state assertion (for still-unsatisfied tuples).
     *
     * By here we have established that the scan's required arrays (scan must
     * have at least one required array) advanced, without becoming exhausted.
     *
     * Caller's tuple is now < the newly advanced array keys (or > when this
     * is a backwards scan), except in the case where we only got this far due
     * to an unsatisfied non-required scan key.  Verify that with an assert.
     *
     * Note: we don't just quit at this point when all required scan keys were
     * found to be satisfied because we need to consider edge-cases involving
     * scan keys required in the opposite direction only; those aren't tracked
     * by all_required_satisfied.
     */
    Assert(_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc, tupnatts,
                                        false, 0, NULL) ==
           !all_required_satisfied);
 
    /*
     * We generally permit primitive index scans to continue onto the next
     * sibling page when the page's finaltup satisfies all required scan keys
     * at the point where we're between pages.
     *
     * If caller's tuple is also the page's finaltup, and we see that required
     * scan keys still aren't satisfied, start a new primitive index scan.
     */
    if (!all_required_satisfied && pstate->finaltup == tuple)
        goto new_prim_scan;
 
    /*
     * Proactively check finaltup (don't wait until finaltup is reached by the
     * scan) when it might well turn out to not be satisfied later on.
     *
     * Note: if so->scanBehind hasn't already been set for finaltup by us,
     * it'll be set during this call to _bt_tuple_before_array_skeys.  Either
     * way, it'll be set correctly (for the whole page) after this point.
     */
    if (!all_required_satisfied && pstate->finaltup &&
        _bt_tuple_before_array_skeys(scan, dir, pstate->finaltup, tupdesc,
                                     BTreeTupleGetNAtts(pstate->finaltup, rel),
                                     false, 0, &so->scanBehind))
        goto new_prim_scan;
 
    /*
     * When we encounter a truncated finaltup high key attribute, we're
     * optimistic about the chances of its corresponding required scan key
     * being satisfied when we go on to recheck it against tuples from this
     * page's right sibling leaf page.  We consider truncated attributes to be
     * satisfied by required scan keys, which allows the primitive index scan
     * to continue to the next leaf page.  We must set so->scanBehind to true
     * to remember that the last page's finaltup had "satisfied" required scan
     * keys for one or more truncated attribute values (scan keys required in
     * _either_ scan direction).
     *
     * There is a chance that _bt_readpage (which checks so->scanBehind) will
     * find that even the sibling leaf page's finaltup is < the new array
     * keys.  When that happens, our optimistic policy will have incurred a
     * single extra leaf page access that could have been avoided.
     *
     * A pessimistic policy would give backward scans a gratuitous advantage
     * over forward scans.  We'd punish forward scans for applying more
     * accurate information from the high key, rather than just using the
     * final non-pivot tuple as finaltup, in the style of backward scans.
     * Being pessimistic would also give some scans with non-required arrays a
     * perverse advantage over similar scans that use required arrays instead.
     *
     * This is similar to our scan-level heuristics, below.  They also set
     * scanBehind to speculatively continue the primscan onto the next page.
     */
    if (so->scanBehind)
    {
        /* Truncated high key -- _bt_scanbehind_checkkeys recheck scheduled */
    }
 
    /*
     * Handle inequalities marked required in the opposite scan direction.
     * They can also signal that we should start a new primitive index scan.
     *
     * It's possible that the scan is now positioned where "matching" tuples
     * begin, and that caller's tuple satisfies all scan keys required in the
     * current scan direction.  But if caller's tuple still doesn't satisfy
     * other scan keys that are required in the opposite scan direction only
     * (e.g., a required >= strategy scan key when scan direction is forward),
     * it's still possible that there are many leaf pages before the page that
     * _bt_first could skip straight to.  Groveling through all those pages
     * will always give correct answers, but it can be very inefficient.  We
     * must avoid needlessly scanning extra pages.
     *
     * Separately, it's possible that _bt_check_compare set continuescan=false
     * for a scan key that's required in the opposite direction only.  This is
     * a special case, that happens only when _bt_check_compare sees that the
     * inequality encountered a NULL value.  This signals the end of non-NULL
     * values in the current scan direction, which is reason enough to end the
     * (primitive) scan.  If this happens at the start of a large group of
     * NULL values, then we shouldn't expect to be called again until after
     * the scan has already read indefinitely-many leaf pages full of tuples
     * with NULL suffix values.  (_bt_first is expected to skip over the group
     * of NULLs by applying a similar "deduce NOT NULL" rule of its own, which
     * involves consing up an explicit SK_SEARCHNOTNULL key.)
     *
     * Apply a test against finaltup to detect and recover from the problem:
     * if even finaltup doesn't satisfy such an inequality, we just skip by
     * starting a new primitive index scan.  When we skip, we know for sure
     * that all of the tuples on the current page following caller's tuple are
     * also before the _bt_first-wise start of tuples for our new qual.  That
     * at least suggests many more skippable pages beyond the current page.
     * (when so->scanBehind and so->oppositeDirCheck are set, this'll happen
     * when we test the next page's finaltup/high key instead.)
     */
    else if (has_required_opposite_direction_only && pstate->finaltup &&
             unlikely(!_bt_oppodir_checkkeys(scan, dir, pstate->finaltup)))
        goto new_prim_scan;
 
continue_scan:
 
    /*
     * Stick with the ongoing primitive index scan for now.
     *
     * It's possible that later tuples will also turn out to have values that
     * are still < the now-current array keys (or > the current array keys).
     * Our caller will handle this by performing what amounts to a linear
     * search of the page, implemented by calling _bt_check_compare and then
     * _bt_tuple_before_array_skeys for each tuple.
     *
     * This approach has various advantages over a binary search of the page.
     * Repeated binary searches of the page (one binary search for every array
     * advancement) won't outperform a continuous linear search.  While there
     * are workloads that a naive linear search won't handle well, our caller
     * has a "look ahead" fallback mechanism to deal with that problem.
     */
    pstate->continuescan = true;    /* Override _bt_check_compare */
    so->needPrimScan = false;   /* _bt_readpage has more tuples to check */
 
    if (so->scanBehind)
    {
        /*
         * Remember if recheck needs to call _bt_oppodir_checkkeys for next
         * page's finaltup (see above comments about "Handle inequalities
         * marked required in the opposite scan direction" for why).
         */
        so->oppositeDirCheck = has_required_opposite_direction_only;
 
        /*
         * skip by setting "look ahead" mechanism's offnum for forwards scans
         * (backwards scans check scanBehind flag directly instead)
         */
        if (ScanDirectionIsForward(dir))
            pstate->skip = pstate->maxoff + 1;
    }
 
    /* Caller's tuple doesn't match the new qual */
    return false;
 
new_prim_scan:
 
    Assert(pstate->finaltup);   /* not on rightmost/leftmost page */
 
    /*
     * Looks like another primitive index scan is required.  But consider
     * continuing the current primscan based on scan-level heuristics.
     *
     * Continue the ongoing primitive scan (and schedule a recheck for when
     * the scan arrives on the next sibling leaf page) when it has already
     * read at least one leaf page before the one we're reading now.  This
     * makes primscan scheduling more efficient when scanning subsets of an
     * index with many distinct attribute values matching many array elements.
     * It encourages fewer, larger primitive scans where that makes sense.
     * This will in turn encourage _bt_readpage to apply the pstate.startikey
     * optimization more often.
     *
     * Also continue the ongoing primitive index scan when it is still on the
     * first page if there have been more than NSKIPADVANCES_THRESHOLD calls
     * here that each advanced at least one of the scan's skip arrays
     * (deliberately ignore advancements that only affected SAOP arrays here).
     * A page that cycles through this many skip array elements is quite
     * likely to neighbor similar pages, that we'll also need to read.
     *
     * Note: These heuristics aren't as aggressive as you might think.  We're
     * conservative about allowing a primitive scan to step from the first
     * leaf page it reads to the page's sibling page (we only allow it on
     * first pages whose finaltup strongly suggests that it'll work out, as
     * well as first pages that have a large number of skip array advances).
     * Clearing this first page finaltup hurdle is a strong signal in itself.
     *
     * Note: The NSKIPADVANCES_THRESHOLD heuristic exists only to avoid
     * pathological cases.  Specifically, cases where a skip scan should just
     * behave like a traditional full index scan, but ends up "skipping" again
     * and again, descending to the prior leaf page's direct sibling leaf page
     * each time.  This misbehavior would otherwise be possible during scans
     * that never quite manage to "clear the first page finaltup hurdle".
     */
    if (!pstate->firstpage || pstate->nskipadvances > NSKIPADVANCES_THRESHOLD)
    {
        /* Schedule a recheck once on the next (or previous) page */
        so->scanBehind = true;
 
        /* Continue the current primitive scan after all */
        goto continue_scan;
    }
 
    /*
     * End this primitive index scan, but schedule another.
     *
     * Note: We make a soft assumption that the current scan direction will
     * also be used within _bt_next, when it is asked to step off this page.
     * It is up to _bt_next to cancel this scheduled primitive index scan
     * whenever it steps to a page in the direction opposite currPos.dir.
     */
    pstate->continuescan = false;   /* Tell _bt_readpage we're done... */
    so->needPrimScan = true;    /* ...but call _bt_first again */
 
    if (scan->parallel_scan)
        _bt_parallel_primscan_schedule(scan, so->currPos.currPage);
 
    /* Caller's tuple doesn't match the new qual */
    return false;
 
end_toplevel_scan:
 
    /*
     * End the current primitive index scan, but don't schedule another.
     *
     * This ends the entire top-level scan in the current scan direction.
     *
     * Note: The scan's arrays (including any non-required arrays) are now in
     * their final positions for the current scan direction.  If the scan
     * direction happens to change, then the arrays will already be in their
     * first positions for what will then be the current scan direction.
     */
    pstate->continuescan = false;   /* Tell _bt_readpage we're done... */
    so->needPrimScan = false;   /* ...and don't call _bt_first again */
 
    /* Caller's tuple doesn't match any qual */
    return false;
}

References _bt_advance_array_keys(), _bt_advance_array_keys_increment(), _bt_array_set_low_or_high(), _bt_binsrch_array_skey(), _bt_binsrch_skiparray_skey(), _bt_check_compare(), _bt_compare_array_skey(), _bt_oppodir_checkkeys(), _bt_parallel_primscan_schedule(), _bt_skiparray_set_element(), _bt_tuple_before_array_skeys(), Assert, BTEqualStrategyNumber, BTreeTupleGetNAtts, BTReadPageState::continuescan, cur, BTArrayKeyInfo::cur_elem, BTReadPageState::dir, BTArrayKeyInfo::elem_values, fb(), BTReadPageState::finaltup, BTReadPageState::firstpage, ForwardScanDirection, index_getattr(), IndexScanDescData::indexRelation, BTReadPageState::maxoff, BTReadPageState::nskipadvances, NSKIPADVANCES_THRESHOLD, BTArrayKeyInfo::num_elems, IndexScanDescData::opaque, IndexScanDescData::parallel_scan, PG_USED_FOR_ASSERTS_ONLY, BTReadPageState::rechecks, BTArrayKeyInfo::scan_key, ScanDirectionIsBackward, ScanDirectionIsForward, SK_BT_REQBKWD, SK_BT_REQFWD, SK_SEARCHARRAY, BTReadPageState::skip, BTReadPageState::targetdistance, and unlikely.

Referenced by _bt_advance_array_keys(), _bt_check_compare(), and _bt_checkkeys().

_bt_advance_array_keys_increment()

static bool _bt_advance_array_keys_increment ( IndexScanDesc  scan, ScanDirection  dir, bool *  skip_array_set  )

static

Definition at line 2868 of file nbtreadpage.c.

{
    Relation    rel = scan->indexRelation;
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
 
    /*
     * We must advance the last array key most quickly, since it will
     * correspond to the lowest-order index column among the available
     * qualifications
     */
    for (int i = so->numArrayKeys - 1; i >= 0; i--)
    {
        BTArrayKeyInfo *array = &so->arrayKeys[i];
        ScanKey     skey = &so->keyData[array->scan_key];
 
        if (array->num_elems == -1)
            *skip_array_set = true;
 
        if (ScanDirectionIsForward(dir))
        {
            if (_bt_array_increment(rel, skey, array))
                return true;
        }
        else
        {
            if (_bt_array_decrement(rel, skey, array))
                return true;
        }
 
        /*
         * Couldn't increment (or decrement) array.  Handle array roll over.
         *
         * Start over at the array's lowest sorting value (or its highest
         * value, for backward scans)...
         */
        _bt_array_set_low_or_high(rel, skey, array,
                                  ScanDirectionIsForward(dir));
 
        /* ...then increment (or decrement) next most significant array */
    }
 
    /*
     * The array keys are now exhausted.
     *
     * Restore the array keys to the state they were in immediately before we
     * were called.  This ensures that the arrays only ever ratchet in the
     * current scan direction.
     *
     * Without this, scans could overlook matching tuples when the scan
     * direction gets reversed just before btgettuple runs out of items to
     * return, but just after _bt_readpage prepares all the items from the
     * scan's final page in so->currPos.  When we're on the final page it is
     * typical for so->currPos to get invalidated once btgettuple finally
     * returns false, which'll effectively invalidate the scan's array keys.
     * That hasn't happened yet, though -- and in general it may never happen.
     */
    _bt_start_array_keys(scan, -dir);
 
    return false;
}

References _bt_array_decrement(), _bt_array_increment(), _bt_array_set_low_or_high(), _bt_start_array_keys(), fb(), i, IndexScanDescData::indexRelation, BTArrayKeyInfo::num_elems, IndexScanDescData::opaque, BTArrayKeyInfo::scan_key, and ScanDirectionIsForward.

Referenced by _bt_advance_array_keys().

_bt_array_decrement()

static bool _bt_array_decrement ( Relation  rel, ScanKey  skey, BTArrayKeyInfo *  array  )

static

Definition at line 3070 of file nbtreadpage.c.

{
    bool        uflow = false;
    Datum       dec_sk_argument;
 
    Assert(skey->sk_flags & SK_SEARCHARRAY);
    Assert(!(skey->sk_flags & (SK_BT_MAXVAL | SK_BT_NEXT | SK_BT_PRIOR)));
 
    /* SAOP array? */
    if (array->num_elems != -1)
    {
        Assert(!(skey->sk_flags & (SK_BT_SKIP | SK_BT_MINVAL | SK_BT_MAXVAL)));
        if (array->cur_elem > 0)
        {
            /*
             * Just decrement current element, and assign its datum to skey
             * (only skip arrays need us to free existing sk_argument memory)
             */
            array->cur_elem--;
            skey->sk_argument = array->elem_values[array->cur_elem];
 
            /* Successfully decremented array */
            return true;
        }
 
        /* Cannot decrement to before first array element */
        return false;
    }
 
    /* Nope, this is a skip array */
    Assert(skey->sk_flags & SK_BT_SKIP);
 
    /*
     * The sentinel value that represents the minimum value within the range
     * of a skip array (often just -inf) is never decrementable
     */
    if (skey->sk_flags & SK_BT_MINVAL)
        return false;
 
    /*
     * When the current array element is NULL, and the lowest sorting value in
     * the index is also NULL, we cannot decrement before first array element
     */
    if ((skey->sk_flags & SK_ISNULL) && (skey->sk_flags & SK_BT_NULLS_FIRST))
        return false;
 
    /*
     * Opclasses without skip support "decrement" the scan key's current
     * element by setting the PRIOR flag.  The true prior value is determined
     * by repositioning to the last index tuple < existing sk_argument/current
     * array element.  Note that this works in the usual way when the scan key
     * is already marked ISNULL (i.e. when the current element is NULL).
     */
    if (!array->sksup)
    {
        /* Successfully "decremented" array */
        skey->sk_flags |= SK_BT_PRIOR;
        return true;
    }
 
    /*
     * Opclasses with skip support directly decrement sk_argument
     */
    if (skey->sk_flags & SK_ISNULL)
    {
        Assert(!(skey->sk_flags & SK_BT_NULLS_FIRST));
 
        /*
         * Existing sk_argument/array element is NULL (for an IS NULL qual).
         *
         * "Decrement" from NULL to the high_elem value provided by opclass
         * skip support routine.
         */
        skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL);
        skey->sk_argument = datumCopy(array->sksup->high_elem,
                                      array->attbyval, array->attlen);
        return true;
    }
 
    /*
     * Ask opclass support routine to provide decremented copy of existing
     * non-NULL sk_argument
     */
    dec_sk_argument = array->sksup->decrement(rel, skey->sk_argument, &uflow);
    if (unlikely(uflow))
    {
        /* dec_sk_argument has undefined value (so no pfree) */
        if (array->null_elem && (skey->sk_flags & SK_BT_NULLS_FIRST))
        {
            _bt_skiparray_set_isnull(rel, skey, array);
 
            /* Successfully "decremented" array to NULL */
            return true;
        }
 
        /* Cannot decrement to before first array element */
        return false;
    }
 
    /*
     * Successfully decremented sk_argument to a non-NULL value.  Make sure
     * that the decremented value is still within the range of the array.
     */
    if (array->low_compare &&
        !DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
                                        array->low_compare->sk_collation,
                                        dec_sk_argument,
                                        array->low_compare->sk_argument)))
    {
        /* Keep existing sk_argument after all */
        if (!array->attbyval)
            pfree(DatumGetPointer(dec_sk_argument));
 
        /* Cannot decrement to before first array element */
        return false;
    }
 
    /* Accept value returned by opclass decrement callback */
    if (!array->attbyval && skey->sk_argument)
        pfree(DatumGetPointer(skey->sk_argument));
    skey->sk_argument = dec_sk_argument;
 
    /* Successfully decremented array */
    return true;
}

References _bt_skiparray_set_isnull(), Assert, BTArrayKeyInfo::attbyval, BTArrayKeyInfo::attlen, BTArrayKeyInfo::cur_elem, datumCopy(), DatumGetBool(), DatumGetPointer(), SkipSupportData::decrement, BTArrayKeyInfo::elem_values, fb(), FunctionCall2Coll(), SkipSupportData::high_elem, BTArrayKeyInfo::low_compare, BTArrayKeyInfo::null_elem, BTArrayKeyInfo::num_elems, pfree(), ScanKeyData::sk_argument, SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_NULLS_FIRST, SK_BT_PRIOR, SK_BT_SKIP, ScanKeyData::sk_collation, ScanKeyData::sk_func, SK_ISNULL, SK_SEARCHARRAY, SK_SEARCHNULL, BTArrayKeyInfo::sksup, and unlikely.

Referenced by _bt_advance_array_keys_increment().

_bt_array_increment()

static bool _bt_array_increment ( Relation  rel, ScanKey  skey, BTArrayKeyInfo *  array  )

static

Definition at line 2937 of file nbtreadpage.c.

{
    bool        oflow = false;
    Datum       inc_sk_argument;
 
    Assert(skey->sk_flags & SK_SEARCHARRAY);
    Assert(!(skey->sk_flags & (SK_BT_MINVAL | SK_BT_NEXT | SK_BT_PRIOR)));
 
    /* SAOP array? */
    if (array->num_elems != -1)
    {
        Assert(!(skey->sk_flags & (SK_BT_SKIP | SK_BT_MINVAL | SK_BT_MAXVAL)));
        if (array->cur_elem < array->num_elems - 1)
        {
            /*
             * Just increment current element, and assign its datum to skey
             * (only skip arrays need us to free existing sk_argument memory)
             */
            array->cur_elem++;
            skey->sk_argument = array->elem_values[array->cur_elem];
 
            /* Successfully incremented array */
            return true;
        }
 
        /* Cannot increment past final array element */
        return false;
    }
 
    /* Nope, this is a skip array */
    Assert(skey->sk_flags & SK_BT_SKIP);
 
    /*
     * The sentinel value that represents the maximum value within the range
     * of a skip array (often just +inf) is never incrementable
     */
    if (skey->sk_flags & SK_BT_MAXVAL)
        return false;
 
    /*
     * When the current array element is NULL, and the highest sorting value
     * in the index is also NULL, we cannot increment past the final element
     */
    if ((skey->sk_flags & SK_ISNULL) && !(skey->sk_flags & SK_BT_NULLS_FIRST))
        return false;
 
    /*
     * Opclasses without skip support "increment" the scan key's current
     * element by setting the NEXT flag.  The true next value is determined by
     * repositioning to the first index tuple > existing sk_argument/current
     * array element.  Note that this works in the usual way when the scan key
     * is already marked ISNULL (i.e. when the current element is NULL).
     */
    if (!array->sksup)
    {
        /* Successfully "incremented" array */
        skey->sk_flags |= SK_BT_NEXT;
        return true;
    }
 
    /*
     * Opclasses with skip support directly increment sk_argument
     */
    if (skey->sk_flags & SK_ISNULL)
    {
        Assert(skey->sk_flags & SK_BT_NULLS_FIRST);
 
        /*
         * Existing sk_argument/array element is NULL (for an IS NULL qual).
         *
         * "Increment" from NULL to the low_elem value provided by opclass
         * skip support routine.
         */
        skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL);
        skey->sk_argument = datumCopy(array->sksup->low_elem,
                                      array->attbyval, array->attlen);
        return true;
    }
 
    /*
     * Ask opclass support routine to provide incremented copy of existing
     * non-NULL sk_argument
     */
    inc_sk_argument = array->sksup->increment(rel, skey->sk_argument, &oflow);
    if (unlikely(oflow))
    {
        /* inc_sk_argument has undefined value (so no pfree) */
        if (array->null_elem && !(skey->sk_flags & SK_BT_NULLS_FIRST))
        {
            _bt_skiparray_set_isnull(rel, skey, array);
 
            /* Successfully "incremented" array to NULL */
            return true;
        }
 
        /* Cannot increment past final array element */
        return false;
    }
 
    /*
     * Successfully incremented sk_argument to a non-NULL value.  Make sure
     * that the incremented value is still within the range of the array.
     */
    if (array->high_compare &&
        !DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
                                        array->high_compare->sk_collation,
                                        inc_sk_argument,
                                        array->high_compare->sk_argument)))
    {
        /* Keep existing sk_argument after all */
        if (!array->attbyval)
            pfree(DatumGetPointer(inc_sk_argument));
 
        /* Cannot increment past final array element */
        return false;
    }
 
    /* Accept value returned by opclass increment callback */
    if (!array->attbyval && skey->sk_argument)
        pfree(DatumGetPointer(skey->sk_argument));
    skey->sk_argument = inc_sk_argument;
 
    /* Successfully incremented array */
    return true;
}

References _bt_skiparray_set_isnull(), Assert, BTArrayKeyInfo::attbyval, BTArrayKeyInfo::attlen, BTArrayKeyInfo::cur_elem, datumCopy(), DatumGetBool(), DatumGetPointer(), BTArrayKeyInfo::elem_values, fb(), FunctionCall2Coll(), BTArrayKeyInfo::high_compare, SkipSupportData::increment, SkipSupportData::low_elem, BTArrayKeyInfo::null_elem, BTArrayKeyInfo::num_elems, pfree(), ScanKeyData::sk_argument, SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_NULLS_FIRST, SK_BT_PRIOR, SK_BT_SKIP, ScanKeyData::sk_collation, ScanKeyData::sk_func, SK_ISNULL, SK_SEARCHARRAY, SK_SEARCHNULL, BTArrayKeyInfo::sksup, and unlikely.

Referenced by _bt_advance_array_keys_increment().

_bt_array_set_low_or_high()

static void _bt_array_set_low_or_high ( Relation  rel, ScanKey  skey, BTArrayKeyInfo *  array, bool  low_not_high  )

static

Definition at line 3203 of file nbtreadpage.c.

{
    Assert(skey->sk_flags & SK_SEARCHARRAY);
 
    if (array->num_elems != -1)
    {
        /* set low or high element for SAOP array */
        int         set_elem = 0;
 
        Assert(!(skey->sk_flags & SK_BT_SKIP));
 
        if (!low_not_high)
            set_elem = array->num_elems - 1;
 
        /*
         * Just copy over array datum (only skip arrays require freeing and
         * allocating memory for sk_argument)
         */
        array->cur_elem = set_elem;
        skey->sk_argument = array->elem_values[set_elem];
 
        return;
    }
 
    /* set low or high element for skip array */
    Assert(skey->sk_flags & SK_BT_SKIP);
    Assert(array->num_elems == -1);
 
    /* Free memory previously allocated for sk_argument if needed */
    if (!array->attbyval && skey->sk_argument)
        pfree(DatumGetPointer(skey->sk_argument));
 
    /* Reset flags */
    skey->sk_argument = (Datum) 0;
    skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL |
                        SK_BT_MINVAL | SK_BT_MAXVAL |
                        SK_BT_NEXT | SK_BT_PRIOR);
 
    if (array->null_elem &&
        (low_not_high == ((skey->sk_flags & SK_BT_NULLS_FIRST) != 0)))
    {
        /* Requested element (either lowest or highest) has the value NULL */
        skey->sk_flags |= (SK_SEARCHNULL | SK_ISNULL);
    }
    else if (low_not_high)
    {
        /* Setting array to lowest element (according to low_compare) */
        skey->sk_flags |= SK_BT_MINVAL;
    }
    else
    {
        /* Setting array to highest element (according to high_compare) */
        skey->sk_flags |= SK_BT_MAXVAL;
    }
}

References Assert, BTArrayKeyInfo::attbyval, BTArrayKeyInfo::cur_elem, DatumGetPointer(), BTArrayKeyInfo::elem_values, fb(), BTArrayKeyInfo::null_elem, BTArrayKeyInfo::num_elems, pfree(), SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_NULLS_FIRST, SK_BT_PRIOR, SK_BT_SKIP, SK_ISNULL, SK_SEARCHARRAY, and SK_SEARCHNULL.

Referenced by _bt_advance_array_keys(), _bt_advance_array_keys_increment(), _bt_skiparray_set_element(), and _bt_start_array_keys().

_bt_binsrch_array_skey()

int _bt_binsrch_array_skey	(	FmgrInfo *	orderproc,
		bool	cur_elem_trig,
		ScanDirection	dir,
		Datum	tupdatum,
		bool	tupnull,
		BTArrayKeyInfo *	array,
		ScanKey	cur,
		int32 *	set_elem_result
	)

Definition at line 3415 of file nbtreadpage.c.

{
    int         low_elem = 0,
                mid_elem = -1,
                high_elem = array->num_elems - 1,
                result = 0;
    Datum       arrdatum;
 
    Assert(cur->sk_flags & SK_SEARCHARRAY);
    Assert(!(cur->sk_flags & SK_BT_SKIP));
    Assert(!(cur->sk_flags & SK_ISNULL));   /* SAOP arrays never have NULLs */
    Assert(cur->sk_strategy == BTEqualStrategyNumber);
 
    if (cur_elem_trig)
    {
        Assert(!ScanDirectionIsNoMovement(dir));
        Assert(cur->sk_flags & SK_BT_REQFWD);
 
        /*
         * When the scan key that triggered array advancement is a required
         * array scan key, it is now certain that the current array element
         * (plus all prior elements relative to the current scan direction)
         * cannot possibly be at or ahead of the corresponding tuple value.
         * (_bt_checkkeys must have called _bt_tuple_before_array_skeys, which
         * makes sure this is true as a condition of advancing the arrays.)
         *
         * This makes it safe to exclude array elements up to and including
         * the former-current array element from our search.
         *
         * Separately, when array advancement was triggered by a required scan
         * key, the array element immediately after the former-current element
         * is often either an exact tupdatum match, or a "close by" near-match
         * (a near-match tupdatum is one whose key space falls _between_ the
         * former-current and new-current array elements).  We'll detect both
         * cases via an optimistic comparison of the new search lower bound
         * (or new search upper bound in the case of backwards scans).
         */
        if (ScanDirectionIsForward(dir))
        {
            low_elem = array->cur_elem + 1; /* old cur_elem exhausted */
 
            /* Compare prospective new cur_elem (also the new lower bound) */
            if (high_elem >= low_elem)
            {
                arrdatum = array->elem_values[low_elem];
                result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
                                                arrdatum, cur);
 
                if (result <= 0)
                {
                    /* Optimistic comparison optimization worked out */
                    *set_elem_result = result;
                    return low_elem;
                }
                mid_elem = low_elem;
                low_elem++;     /* this cur_elem exhausted, too */
            }
 
            if (high_elem < low_elem)
            {
                /* Caller needs to perform "beyond end" array advancement */
                *set_elem_result = 1;
                return high_elem;
            }
        }
        else
        {
            high_elem = array->cur_elem - 1;    /* old cur_elem exhausted */
 
            /* Compare prospective new cur_elem (also the new upper bound) */
            if (high_elem >= low_elem)
            {
                arrdatum = array->elem_values[high_elem];
                result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
                                                arrdatum, cur);
 
                if (result >= 0)
                {
                    /* Optimistic comparison optimization worked out */
                    *set_elem_result = result;
                    return high_elem;
                }
                mid_elem = high_elem;
                high_elem--;    /* this cur_elem exhausted, too */
            }
 
            if (high_elem < low_elem)
            {
                /* Caller needs to perform "beyond end" array advancement */
                *set_elem_result = -1;
                return low_elem;
            }
        }
    }
 
    while (high_elem > low_elem)
    {
        mid_elem = low_elem + ((high_elem - low_elem) / 2);
        arrdatum = array->elem_values[mid_elem];
 
        result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
                                        arrdatum, cur);
 
        if (result == 0)
        {
            /*
             * It's safe to quit as soon as we see an equal array element.
             * This often saves an extra comparison or two...
             */
            low_elem = mid_elem;
            break;
        }
 
        if (result > 0)
            low_elem = mid_elem + 1;
        else
            high_elem = mid_elem;
    }
 
    /*
     * ...but our caller also cares about how its searched-for tuple datum
     * compares to the low_elem datum.  Must always set *set_elem_result with
     * the result of that comparison specifically.
     */
    if (low_elem != mid_elem)
        result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
                                        array->elem_values[low_elem], cur);
 
    *set_elem_result = result;
 
    return low_elem;
}

References _bt_compare_array_skey(), Assert, BTEqualStrategyNumber, cur, BTArrayKeyInfo::cur_elem, BTArrayKeyInfo::elem_values, fb(), BTArrayKeyInfo::num_elems, ScanDirectionIsForward, ScanDirectionIsNoMovement, SK_BT_REQFWD, SK_BT_SKIP, SK_ISNULL, and SK_SEARCHARRAY.

Referenced by _bt_advance_array_keys(), _bt_saoparray_shrink(), and _bt_set_startikey().

_bt_binsrch_skiparray_skey()

static void _bt_binsrch_skiparray_skey ( bool  cur_elem_trig, ScanDirection  dir, Datum  tupdatum, bool  tupnull, BTArrayKeyInfo *  array, ScanKey  cur, int32 *  set_elem_result  )

static

Definition at line 3571 of file nbtreadpage.c.

{
    Assert(cur->sk_flags & SK_BT_SKIP);
    Assert(cur->sk_flags & SK_SEARCHARRAY);
    Assert(cur->sk_flags & SK_BT_REQFWD);
    Assert(array->num_elems == -1);
    Assert(!ScanDirectionIsNoMovement(dir));
 
    if (array->null_elem)
    {
        Assert(!array->low_compare && !array->high_compare);
 
        *set_elem_result = 0;
        return;
    }
 
    if (tupnull)                /* NULL tupdatum */
    {
        if (cur->sk_flags & SK_BT_NULLS_FIRST)
            *set_elem_result = -1;  /* NULL "<" NOT_NULL */
        else
            *set_elem_result = 1;   /* NULL ">" NOT_NULL */
        return;
    }
 
    /*
     * Array inequalities determine whether tupdatum is within the range of
     * caller's skip array
     */
    *set_elem_result = 0;
    if (ScanDirectionIsForward(dir))
    {
        /*
         * Evaluate low_compare first (unless cur_elem_trig tells us that it
         * cannot possibly fail to be satisfied), then evaluate high_compare
         */
        if (!cur_elem_trig && array->low_compare &&
            !DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
                                            array->low_compare->sk_collation,
                                            tupdatum,
                                            array->low_compare->sk_argument)))
            *set_elem_result = -1;
        else if (array->high_compare &&
                 !DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
                                                 array->high_compare->sk_collation,
                                                 tupdatum,
                                                 array->high_compare->sk_argument)))
            *set_elem_result = 1;
    }
    else
    {
        /*
         * Evaluate high_compare first (unless cur_elem_trig tells us that it
         * cannot possibly fail to be satisfied), then evaluate low_compare
         */
        if (!cur_elem_trig && array->high_compare &&
            !DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
                                            array->high_compare->sk_collation,
                                            tupdatum,
                                            array->high_compare->sk_argument)))
            *set_elem_result = 1;
        else if (array->low_compare &&
                 !DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
                                                 array->low_compare->sk_collation,
                                                 tupdatum,
                                                 array->low_compare->sk_argument)))
            *set_elem_result = -1;
    }
 
    /*
     * Assert that any keys that were assumed to be satisfied already (due to
     * caller passing cur_elem_trig=true) really are satisfied as expected
     */
#ifdef USE_ASSERT_CHECKING
    if (cur_elem_trig)
    {
        if (ScanDirectionIsForward(dir) && array->low_compare)
            Assert(DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
                                                  array->low_compare->sk_collation,
                                                  tupdatum,
                                                  array->low_compare->sk_argument)));
 
        if (ScanDirectionIsBackward(dir) && array->high_compare)
            Assert(DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
                                                  array->high_compare->sk_collation,
                                                  tupdatum,
                                                  array->high_compare->sk_argument)));
    }
#endif
}

References Assert, cur, DatumGetBool(), fb(), FunctionCall2Coll(), BTArrayKeyInfo::high_compare, BTArrayKeyInfo::low_compare, BTArrayKeyInfo::null_elem, BTArrayKeyInfo::num_elems, ScanDirectionIsBackward, ScanDirectionIsForward, ScanDirectionIsNoMovement, ScanKeyData::sk_argument, SK_BT_NULLS_FIRST, SK_BT_REQFWD, SK_BT_SKIP, ScanKeyData::sk_collation, ScanKeyData::sk_func, and SK_SEARCHARRAY.

Referenced by _bt_advance_array_keys(), _bt_set_startikey(), and _bt_tuple_before_array_skeys().

_bt_check_compare()

static bool _bt_check_compare ( IndexScanDesc  scan, ScanDirection  dir, IndexTuple  tuple, int  tupnatts, TupleDesc  tupdesc, bool  advancenonrequired, bool  forcenonrequired, bool *  continuescan, int *  ikey  )

static

Definition at line 1312 of file nbtreadpage.c.

{
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
 
    *continuescan = true;       /* default assumption */
 
    for (; *ikey < so->numberOfKeys; (*ikey)++)
    {
        ScanKey     key = so->keyData + *ikey;
        Datum       datum;
        bool        isNull;
        bool        requiredSameDir = false,
                    requiredOppositeDirOnly = false;
 
        /*
         * Check if the key is required in the current scan direction, in the
         * opposite scan direction _only_, or in neither direction (except
         * when we're forced to treat all scan keys as nonrequired)
         */
        if (forcenonrequired)
        {
            /* treating scan's keys as non-required */
        }
        else if (((key->sk_flags & SK_BT_REQFWD) && ScanDirectionIsForward(dir)) ||
                 ((key->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsBackward(dir)))
            requiredSameDir = true;
        else if (((key->sk_flags & SK_BT_REQFWD) && ScanDirectionIsBackward(dir)) ||
                 ((key->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsForward(dir)))
            requiredOppositeDirOnly = true;
 
        if (key->sk_attno > tupnatts)
        {
            /*
             * This attribute is truncated (must be high key).  The value for
             * this attribute in the first non-pivot tuple on the page to the
             * right could be any possible value.  Assume that truncated
             * attribute passes the qual.
             */
            Assert(BTreeTupleIsPivot(tuple));
            continue;
        }
 
        /*
         * A skip array scan key uses one of several sentinel values.  We just
         * fall back on _bt_tuple_before_array_skeys when we see such a value.
         */
        if (key->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL |
                             SK_BT_NEXT | SK_BT_PRIOR))
        {
            Assert(key->sk_flags & SK_SEARCHARRAY);
            Assert(key->sk_flags & SK_BT_SKIP);
            Assert(requiredSameDir || forcenonrequired);
 
            /*
             * Cannot fall back on _bt_tuple_before_array_skeys when we're
             * treating the scan's keys as nonrequired, though.  Just handle
             * this like any other non-required equality-type array key.
             */
            if (forcenonrequired)
                return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
                                              tupdesc, *ikey, false);
 
            *continuescan = false;
            return false;
        }
 
        /* row-comparison keys need special processing */
        if (key->sk_flags & SK_ROW_HEADER)
        {
            if (_bt_check_rowcompare(key, tuple, tupnatts, tupdesc, dir,
                                     forcenonrequired, continuescan))
                continue;
            return false;
        }
 
        datum = index_getattr(tuple,
                              key->sk_attno,
                              tupdesc,
                              &isNull);
 
        if (key->sk_flags & SK_ISNULL)
        {
            /* Handle IS NULL/NOT NULL tests */
            if (key->sk_flags & SK_SEARCHNULL)
            {
                if (isNull)
                    continue;   /* tuple satisfies this qual */
            }
            else
            {
                Assert(key->sk_flags & SK_SEARCHNOTNULL);
                Assert(!(key->sk_flags & SK_BT_SKIP));
                if (!isNull)
                    continue;   /* tuple satisfies this qual */
            }
 
            /*
             * Tuple fails this qual.  If it's a required qual for the current
             * scan direction, then we can conclude no further tuples will
             * pass, either.
             */
            if (requiredSameDir)
                *continuescan = false;
            else if (unlikely(key->sk_flags & SK_BT_SKIP))
            {
                /*
                 * If we're treating scan keys as nonrequired, and encounter a
                 * skip array scan key whose current element is NULL, then it
                 * must be a non-range skip array.  It must be satisfied, so
                 * there's no need to call _bt_advance_array_keys to check.
                 */
                Assert(forcenonrequired && *ikey > 0);
                continue;
            }
 
            /*
             * This indextuple doesn't match the qual.
             */
            return false;
        }
 
        if (isNull)
        {
            /*
             * Scalar scan key isn't satisfied by NULL tuple value.
             *
             * If we're treating scan keys as nonrequired, and key is for a
             * skip array, then we must attempt to advance the array to NULL
             * (if we're successful then the tuple might match the qual).
             */
            if (unlikely(forcenonrequired && key->sk_flags & SK_BT_SKIP))
                return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
                                              tupdesc, *ikey, false);
 
            if (key->sk_flags & SK_BT_NULLS_FIRST)
            {
                /*
                 * Since NULLs are sorted before non-NULLs, we know we have
                 * reached the lower limit of the range of values for this
                 * index attr.  On a backward scan, we can stop if this qual
                 * is one of the "must match" subset.  We can stop regardless
                 * of whether the qual is > or <, so long as it's required,
                 * because it's not possible for any future tuples to pass. On
                 * a forward scan, however, we must keep going, because we may
                 * have initially positioned to the start of the index.
                 * (_bt_advance_array_keys also relies on this behavior during
                 * forward scans.)
                 */
                if ((requiredSameDir || requiredOppositeDirOnly) &&
                    ScanDirectionIsBackward(dir))
                    *continuescan = false;
            }
            else
            {
                /*
                 * Since NULLs are sorted after non-NULLs, we know we have
                 * reached the upper limit of the range of values for this
                 * index attr.  On a forward scan, we can stop if this qual is
                 * one of the "must match" subset.  We can stop regardless of
                 * whether the qual is > or <, so long as it's required,
                 * because it's not possible for any future tuples to pass. On
                 * a backward scan, however, we must keep going, because we
                 * may have initially positioned to the end of the index.
                 * (_bt_advance_array_keys also relies on this behavior during
                 * backward scans.)
                 */
                if ((requiredSameDir || requiredOppositeDirOnly) &&
                    ScanDirectionIsForward(dir))
                    *continuescan = false;
            }
 
            /*
             * This indextuple doesn't match the qual.
             */
            return false;
        }
 
        if (!DatumGetBool(FunctionCall2Coll(&key->sk_func, key->sk_collation,
                                            datum, key->sk_argument)))
        {
            /*
             * Tuple fails this qual.  If it's a required qual for the current
             * scan direction, then we can conclude no further tuples will
             * pass, either.
             */
            if (requiredSameDir)
                *continuescan = false;
 
            /*
             * If this is a non-required equality-type array key, the tuple
             * needs to be checked against every possible array key.  Handle
             * this by "advancing" the scan key's array to a matching value
             * (if we're successful then the tuple might match the qual).
             */
            else if (advancenonrequired &&
                     key->sk_strategy == BTEqualStrategyNumber &&
                     (key->sk_flags & SK_SEARCHARRAY))
                return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
                                              tupdesc, *ikey, false);
 
            /*
             * This indextuple doesn't match the qual.
             */
            return false;
        }
    }
 
    /* If we get here, the tuple passes all index quals. */
    return true;
}

References _bt_advance_array_keys(), _bt_check_rowcompare(), Assert, BTEqualStrategyNumber, BTreeTupleIsPivot(), DatumGetBool(), fb(), FunctionCall2Coll(), index_getattr(), IndexScanDescData::opaque, ScanDirectionIsBackward, ScanDirectionIsForward, SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_NULLS_FIRST, SK_BT_PRIOR, SK_BT_REQBKWD, SK_BT_REQFWD, SK_BT_SKIP, SK_ISNULL, SK_ROW_HEADER, SK_SEARCHARRAY, SK_SEARCHNOTNULL, SK_SEARCHNULL, and unlikely.

Referenced by _bt_advance_array_keys(), _bt_checkkeys(), and _bt_oppodir_checkkeys().

_bt_check_rowcompare()

static bool _bt_check_rowcompare ( ScanKey  header, IndexTuple  tuple, int  tupnatts, TupleDesc  tupdesc, ScanDirection  dir, bool  forcenonrequired, bool *  continuescan  )

static

Definition at line 1579 of file nbtreadpage.c.

{
    ScanKey     subkey = (ScanKey) DatumGetPointer(header->sk_argument);
    int32       cmpresult = 0;
    bool        result;
 
    /* First subkey should be same as the header says */
    Assert(header->sk_flags & SK_ROW_HEADER);
    Assert(subkey->sk_attno == header->sk_attno);
    Assert(subkey->sk_strategy == header->sk_strategy);
 
    /* Loop over columns of the row condition */
    for (;;)
    {
        Datum       datum;
        bool        isNull;
 
        Assert(subkey->sk_flags & SK_ROW_MEMBER);
 
        /* When a NULL row member is compared, the row never matches */
        if (subkey->sk_flags & SK_ISNULL)
        {
            /*
             * Unlike the simple-scankey case, this isn't a disallowed case
             * (except when it's the first row element that has the NULL arg).
             * But it can never match.  If all the earlier row comparison
             * columns are required for the scan direction, we can stop the
             * scan, because there can't be another tuple that will succeed.
             */
            Assert(subkey != (ScanKey) DatumGetPointer(header->sk_argument));
            subkey--;
            if (forcenonrequired)
            {
                /* treating scan's keys as non-required */
            }
            else if ((subkey->sk_flags & SK_BT_REQFWD) &&
                     ScanDirectionIsForward(dir))
                *continuescan = false;
            else if ((subkey->sk_flags & SK_BT_REQBKWD) &&
                     ScanDirectionIsBackward(dir))
                *continuescan = false;
            return false;
        }
 
        if (subkey->sk_attno > tupnatts)
        {
            /*
             * This attribute is truncated (must be high key).  The value for
             * this attribute in the first non-pivot tuple on the page to the
             * right could be any possible value.  Assume that truncated
             * attribute passes the qual.
             */
            Assert(BTreeTupleIsPivot(tuple));
            return true;
        }
 
        datum = index_getattr(tuple,
                              subkey->sk_attno,
                              tupdesc,
                              &isNull);
 
        if (isNull)
        {
            int         reqflags;
 
            if (forcenonrequired)
            {
                /* treating scan's keys as non-required */
            }
            else if (subkey->sk_flags & SK_BT_NULLS_FIRST)
            {
                /*
                 * Since NULLs are sorted before non-NULLs, we know we have
                 * reached the lower limit of the range of values for this
                 * index attr.  On a backward scan, we can stop if this qual
                 * is one of the "must match" subset.  However, on a forwards
                 * scan, we must keep going, because we may have initially
                 * positioned to the start of the index.
                 *
                 * All required NULLS FIRST > row members can use NULL tuple
                 * values to end backwards scans, just like with other values.
                 * A qual "WHERE (a, b, c) > (9, 42, 'foo')" can terminate a
                 * backwards scan upon reaching the index's rightmost "a = 9"
                 * tuple whose "b" column contains a NULL (if not sooner).
                 * Since "b" is NULLS FIRST, we can treat its NULLs as "<" 42.
                 */
                reqflags = SK_BT_REQBKWD;
 
                /*
                 * When a most significant required NULLS FIRST < row compare
                 * member sees NULL tuple values during a backwards scan, it
                 * signals the end of matches for the whole row compare/scan.
                 * A qual "WHERE (a, b, c) < (9, 42, 'foo')" will terminate a
                 * backwards scan upon reaching the rightmost tuple whose "a"
                 * column has a NULL.  The "a" NULL value is "<" 9, and yet
                 * our < row compare will still end the scan.  (This isn't
                 * safe with later/lower-order row members.  Notice that it
                 * can only happen with an "a" NULL some time after the scan
                 * completely stops needing to use its "b" and "c" members.)
                 */
                if (subkey == (ScanKey) DatumGetPointer(header->sk_argument))
                    reqflags |= SK_BT_REQFWD;   /* safe, first row member */
 
                if ((subkey->sk_flags & reqflags) &&
                    ScanDirectionIsBackward(dir))
                    *continuescan = false;
            }
            else
            {
                /*
                 * Since NULLs are sorted after non-NULLs, we know we have
                 * reached the upper limit of the range of values for this
                 * index attr.  On a forward scan, we can stop if this qual is
                 * one of the "must match" subset.  However, on a backward
                 * scan, we must keep going, because we may have initially
                 * positioned to the end of the index.
                 *
                 * All required NULLS LAST < row members can use NULL tuple
                 * values to end forwards scans, just like with other values.
                 * A qual "WHERE (a, b, c) < (9, 42, 'foo')" can terminate a
                 * forwards scan upon reaching the index's leftmost "a = 9"
                 * tuple whose "b" column contains a NULL (if not sooner).
                 * Since "b" is NULLS LAST, we can treat its NULLs as ">" 42.
                 */
                reqflags = SK_BT_REQFWD;
 
                /*
                 * When a most significant required NULLS LAST > row compare
                 * member sees NULL tuple values during a forwards scan, it
                 * signals the end of matches for the whole row compare/scan.
                 * A qual "WHERE (a, b, c) > (9, 42, 'foo')" will terminate a
                 * forwards scan upon reaching the leftmost tuple whose "a"
                 * column has a NULL.  The "a" NULL value is ">" 9, and yet
                 * our > row compare will end the scan.  (This isn't safe with
                 * later/lower-order row members.  Notice that it can only
                 * happen with an "a" NULL some time after the scan completely
                 * stops needing to use its "b" and "c" members.)
                 */
                if (subkey == (ScanKey) DatumGetPointer(header->sk_argument))
                    reqflags |= SK_BT_REQBKWD;  /* safe, first row member */
 
                if ((subkey->sk_flags & reqflags) &&
                    ScanDirectionIsForward(dir))
                    *continuescan = false;
            }
 
            /*
             * In any case, this indextuple doesn't match the qual.
             */
            return false;
        }
 
        /* Perform the test --- three-way comparison not bool operator */
        cmpresult = DatumGetInt32(FunctionCall2Coll(&subkey->sk_func,
                                                    subkey->sk_collation,
                                                    datum,
                                                    subkey->sk_argument));
 
        if (subkey->sk_flags & SK_BT_DESC)
            INVERT_COMPARE_RESULT(cmpresult);
 
        /* Done comparing if unequal, else advance to next column */
        if (cmpresult != 0)
            break;
 
        if (subkey->sk_flags & SK_ROW_END)
            break;
        subkey++;
    }
 
    /* Final subkey/column determines if row compare is satisfied */
    result = _bt_rowcompare_cmpresult(subkey, cmpresult);
 
    if (!result && !forcenonrequired)
    {
        /*
         * Tuple fails this qual.  If it's a required qual for the current
         * scan direction, then we can conclude no further tuples will pass,
         * either.  Note we have to look at the deciding column, not
         * necessarily the first or last column of the row condition.
         */
        if ((subkey->sk_flags & SK_BT_REQFWD) &&
            ScanDirectionIsForward(dir))
            *continuescan = false;
        else if ((subkey->sk_flags & SK_BT_REQBKWD) &&
                 ScanDirectionIsBackward(dir))
            *continuescan = false;
    }
 
    return result;
}

References _bt_rowcompare_cmpresult(), Assert, BTreeTupleIsPivot(), DatumGetInt32(), DatumGetPointer(), fb(), FunctionCall2Coll(), index_getattr(), INVERT_COMPARE_RESULT, ScanDirectionIsBackward, ScanDirectionIsForward, ScanKeyData::sk_argument, ScanKeyData::sk_attno, SK_BT_DESC, SK_BT_NULLS_FIRST, SK_BT_REQBKWD, SK_BT_REQFWD, ScanKeyData::sk_flags, SK_ISNULL, SK_ROW_END, SK_ROW_HEADER, SK_ROW_MEMBER, and ScanKeyData::sk_strategy.

Referenced by _bt_check_compare().

_bt_checkkeys()

static bool _bt_checkkeys ( IndexScanDesc  scan, BTReadPageState *  pstate, bool  arrayKeys, IndexTuple  tuple, int  tupnatts  )

static

Definition at line 1149 of file nbtreadpage.c.

{
    TupleDesc   tupdesc = RelationGetDescr(scan->indexRelation);
    BTScanOpaque so PG_USED_FOR_ASSERTS_ONLY = (BTScanOpaque) scan->opaque;
    ScanDirection dir = pstate->dir;
    int         ikey = pstate->startikey;
    bool        res;
 
    Assert(BTreeTupleGetNAtts(tuple, scan->indexRelation) == tupnatts);
    Assert(!so->needPrimScan && !so->scanBehind && !so->oppositeDirCheck);
    Assert(arrayKeys || so->numArrayKeys == 0);
 
    res = _bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, arrayKeys,
                            pstate->forcenonrequired, &pstate->continuescan,
                            &ikey);
 
    /*
     * If _bt_check_compare relied on the pstate.startikey optimization, call
     * again (in assert-enabled builds) to verify it didn't affect our answer.
     *
     * Note: we can't do this when !pstate.forcenonrequired, since any arrays
     * before pstate.startikey won't have advanced on this page at all.
     */
    Assert(!pstate->forcenonrequired || arrayKeys);
#ifdef USE_ASSERT_CHECKING
    if (pstate->startikey > 0 && !pstate->forcenonrequired)
    {
        bool        dres,
                    dcontinuescan;
        int         dikey = 0;
 
        /* Pass advancenonrequired=false to avoid array side-effects */
        dres = _bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
                                 pstate->forcenonrequired, &dcontinuescan,
                                 &dikey);
        Assert(res == dres);
        Assert(pstate->continuescan == dcontinuescan);
 
        /*
         * Should also get the same ikey result.  We need a slightly weaker
         * assertion during arrayKeys calls, since they might be using an
         * array that couldn't be marked required during preprocessing.
         */
        Assert(arrayKeys || ikey == dikey);
        Assert(ikey <= dikey);
    }
#endif
 
    /*
     * Only one _bt_check_compare call is required in the common case where
     * there are no equality strategy array scan keys.  With array keys, we
     * can only accept _bt_check_compare's answer unreservedly when it set
     * pstate.continuescan=true.
     */
    if (!arrayKeys || pstate->continuescan)
        return res;
 
    /*
     * _bt_check_compare call set continuescan=false in the presence of
     * equality type array keys.  This could mean that the tuple is just past
     * the end of matches for the current array keys.
     *
     * It's also possible that the scan is still _before_ the _start_ of
     * tuples matching the current set of array keys.  Check for that first.
     */
    Assert(!pstate->forcenonrequired);
    if (_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc, tupnatts, true,
                                     ikey, NULL))
    {
        /* Override _bt_check_compare, continue primitive scan */
        pstate->continuescan = true;
 
        /*
         * We will end up here repeatedly given a group of tuples > the
         * previous array keys and < the now-current keys (for a backwards
         * scan it's just the same, though the operators swap positions).
         *
         * We must avoid allowing this linear search process to scan very many
         * tuples from well before the start of tuples matching the current
         * array keys (or from well before the point where we'll once again
         * have to advance the scan's array keys).
         *
         * We keep the overhead under control by speculatively "looking ahead"
         * to later still-unscanned items from this same leaf page.  We'll
         * only attempt this once the number of tuples that the linear search
         * process has examined starts to get out of hand.
         */
        pstate->rechecks++;
        if (pstate->rechecks >= LOOK_AHEAD_REQUIRED_RECHECKS)
        {
            /* See if we should skip ahead within the current leaf page */
            _bt_checkkeys_look_ahead(scan, pstate, tupnatts, tupdesc);
 
            /*
             * Might have set pstate.skip to a later page offset.  When that
             * happens then _bt_readpage caller will inexpensively skip ahead
             * to a later tuple from the same page (the one just after the
             * tuple we successfully "looked ahead" to).
             */
        }
 
        /* This indextuple doesn't match the current qual, in any case */
        return false;
    }
 
    /*
     * Caller's tuple is >= the current set of array keys and other equality
     * constraint scan keys (or <= if this is a backwards scan).  It's now
     * clear that we _must_ advance any required array keys in lockstep with
     * the scan.
     */
    return _bt_advance_array_keys(scan, pstate, tuple, tupnatts, tupdesc,
                                  ikey, true);
}

References _bt_advance_array_keys(), _bt_check_compare(), _bt_checkkeys_look_ahead(), _bt_tuple_before_array_skeys(), Assert, BTreeTupleGetNAtts, BTReadPageState::continuescan, BTReadPageState::dir, fb(), BTReadPageState::forcenonrequired, IndexScanDescData::indexRelation, LOOK_AHEAD_REQUIRED_RECHECKS, IndexScanDescData::opaque, PG_USED_FOR_ASSERTS_ONLY, BTReadPageState::rechecks, RelationGetDescr, and BTReadPageState::startikey.

Referenced by _bt_readpage().

_bt_checkkeys_look_ahead()

static void _bt_checkkeys_look_ahead ( IndexScanDesc  scan, BTReadPageState *  pstate, int  tupnatts, TupleDesc  tupdesc  )

static

Definition at line 2052 of file nbtreadpage.c.

{
    ScanDirection dir = pstate->dir;
    OffsetNumber aheadoffnum;
    IndexTuple  ahead;
 
    Assert(!pstate->forcenonrequired);
 
    /* Avoid looking ahead when comparing the page high key */
    if (pstate->offnum < pstate->minoff)
        return;
 
    /*
     * Don't look ahead when there aren't enough tuples remaining on the page
     * (in the current scan direction) for it to be worth our while
     */
    if (ScanDirectionIsForward(dir) &&
        pstate->offnum >= pstate->maxoff - LOOK_AHEAD_DEFAULT_DISTANCE)
        return;
    else if (ScanDirectionIsBackward(dir) &&
             pstate->offnum <= pstate->minoff + LOOK_AHEAD_DEFAULT_DISTANCE)
        return;
 
    /*
     * The look ahead distance starts small, and ramps up as each call here
     * allows _bt_readpage to skip over more tuples
     */
    if (!pstate->targetdistance)
        pstate->targetdistance = LOOK_AHEAD_DEFAULT_DISTANCE;
    else if (pstate->targetdistance < MaxIndexTuplesPerPage / 2)
        pstate->targetdistance *= 2;
 
    /* Don't read past the end (or before the start) of the page, though */
    if (ScanDirectionIsForward(dir))
        aheadoffnum = Min((int) pstate->maxoff,
                          (int) pstate->offnum + pstate->targetdistance);
    else
        aheadoffnum = Max((int) pstate->minoff,
                          (int) pstate->offnum - pstate->targetdistance);
 
    ahead = (IndexTuple) PageGetItem(pstate->page,
                                     PageGetItemId(pstate->page, aheadoffnum));
    if (_bt_tuple_before_array_skeys(scan, dir, ahead, tupdesc, tupnatts,
                                     false, 0, NULL))
    {
        /*
         * Success -- instruct _bt_readpage to skip ahead to very next tuple
         * after the one we determined was still before the current array keys
         */
        if (ScanDirectionIsForward(dir))
            pstate->skip = aheadoffnum + 1;
        else
            pstate->skip = aheadoffnum - 1;
    }
    else
    {
        /*
         * Failure -- "ahead" tuple is too far ahead (we were too aggressive).
         *
         * Reset the number of rechecks, and aggressively reduce the target
         * distance (we're much more aggressive here than we were when the
         * distance was initially ramped up).
         */
        pstate->rechecks = 0;
        pstate->targetdistance = Max(pstate->targetdistance / 8, 1);
    }
}

References _bt_tuple_before_array_skeys(), Assert, BTReadPageState::dir, fb(), BTReadPageState::forcenonrequired, LOOK_AHEAD_DEFAULT_DISTANCE, Max, MaxIndexTuplesPerPage, BTReadPageState::maxoff, Min, BTReadPageState::minoff, BTReadPageState::offnum, BTReadPageState::page, PageGetItem(), PageGetItemId(), BTReadPageState::rechecks, ScanDirectionIsBackward, ScanDirectionIsForward, BTReadPageState::skip, and BTReadPageState::targetdistance.

Referenced by _bt_checkkeys().

_bt_compare_array_skey()

static int32 _bt_compare_array_skey ( FmgrInfo *  orderproc, Datum  tupdatum, bool  tupnull, Datum  arrdatum, ScanKey  cur  )

inlinestatic

Definition at line 3344 of file nbtreadpage.c.

{
    int32       result = 0;
 
    Assert(cur->sk_strategy == BTEqualStrategyNumber);
    Assert(!(cur->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL)));
 
    if (tupnull)                /* NULL tupdatum */
    {
        if (cur->sk_flags & SK_ISNULL)
            result = 0;         /* NULL "=" NULL */
        else if (cur->sk_flags & SK_BT_NULLS_FIRST)
            result = -1;        /* NULL "<" NOT_NULL */
        else
            result = 1;         /* NULL ">" NOT_NULL */
    }
    else if (cur->sk_flags & SK_ISNULL) /* NOT_NULL tupdatum, NULL arrdatum */
    {
        if (cur->sk_flags & SK_BT_NULLS_FIRST)
            result = 1;         /* NOT_NULL ">" NULL */
        else
            result = -1;        /* NOT_NULL "<" NULL */
    }
    else
    {
        /*
         * Like _bt_compare, we need to be careful of cross-type comparisons,
         * so the left value has to be the value that came from an index tuple
         */
        result = DatumGetInt32(FunctionCall2Coll(orderproc, cur->sk_collation,
                                                 tupdatum, arrdatum));
 
        /*
         * We flip the sign by following the obvious rule: flip whenever the
         * column is a DESC column.
         *
         * _bt_compare does it the wrong way around (flip when *ASC*) in order
         * to compensate for passing its orderproc arguments backwards.  We
         * don't need to play these games because we find it natural to pass
         * tupdatum as the left value (and arrdatum as the right value).
         */
        if (cur->sk_flags & SK_BT_DESC)
            INVERT_COMPARE_RESULT(result);
    }
 
    return result;
}

References Assert, BTEqualStrategyNumber, cur, DatumGetInt32(), fb(), FunctionCall2Coll(), INVERT_COMPARE_RESULT, SK_BT_DESC, SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NULLS_FIRST, and SK_ISNULL.

Referenced by _bt_advance_array_keys(), _bt_binsrch_array_skey(), and _bt_tuple_before_array_skeys().

_bt_oppodir_checkkeys()

static bool _bt_oppodir_checkkeys ( IndexScanDesc  scan, ScanDirection  dir, IndexTuple  finaltup  )

static

Definition at line 1007 of file nbtreadpage.c.

{
    Relation    rel = scan->indexRelation;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
    int         nfinaltupatts = BTreeTupleGetNAtts(finaltup, rel);
    bool        continuescan;
    ScanDirection flipped = -dir;
    int         ikey = 0;
 
    Assert(so->numArrayKeys);
 
    _bt_check_compare(scan, flipped, finaltup, nfinaltupatts, tupdesc, false,
                      false, &continuescan,
                      &ikey);
 
    if (!continuescan && so->keyData[ikey].sk_strategy != BTEqualStrategyNumber)
        return false;
 
    return true;
}

References _bt_check_compare(), Assert, BTEqualStrategyNumber, BTreeTupleGetNAtts, fb(), IndexScanDescData::indexRelation, IndexScanDescData::opaque, and RelationGetDescr.

Referenced by _bt_advance_array_keys(), and _bt_scanbehind_checkkeys().

_bt_readpage()

bool _bt_readpage	(	IndexScanDesc	scan,
		ScanDirection	dir,
		OffsetNumber	offnum,
		bool	firstpage
	)

Definition at line 134 of file nbtreadpage.c.

{
    Relation    rel = scan->indexRelation;
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
    Page        page;
    BTPageOpaque opaque;
    OffsetNumber minoff;
    OffsetNumber maxoff;
    BTReadPageState pstate;
    bool        arrayKeys,
                ignore_killed_tuples = scan->ignore_killed_tuples;
    int         itemIndex,
                indnatts;
 
    /* save the page/buffer block number, along with its sibling links */
    page = BufferGetPage(so->currPos.buf);
    opaque = BTPageGetOpaque(page);
    so->currPos.currPage = BufferGetBlockNumber(so->currPos.buf);
    so->currPos.prevPage = opaque->btpo_prev;
    so->currPos.nextPage = opaque->btpo_next;
    /* delay setting so->currPos.lsn until _bt_drop_lock_and_maybe_pin */
    pstate.dir = so->currPos.dir = dir;
    so->currPos.nextTupleOffset = 0;
 
    /* either moreRight or moreLeft should be set now (may be unset later) */
    Assert(ScanDirectionIsForward(dir) ? so->currPos.moreRight :
           so->currPos.moreLeft);
    Assert(!P_IGNORE(opaque));
    Assert(BTScanPosIsPinned(so->currPos));
    Assert(!so->needPrimScan);
 
    /* initialize local variables */
    indnatts = IndexRelationGetNumberOfAttributes(rel);
    arrayKeys = so->numArrayKeys != 0;
    minoff = P_FIRSTDATAKEY(opaque);
    maxoff = PageGetMaxOffsetNumber(page);
 
    /* initialize page-level state that we'll pass to _bt_checkkeys */
    pstate.minoff = minoff;
    pstate.maxoff = maxoff;
    pstate.finaltup = NULL;
    pstate.page = page;
    pstate.firstpage = firstpage;
    pstate.forcenonrequired = false;
    pstate.startikey = 0;
    pstate.offnum = InvalidOffsetNumber;
    pstate.skip = InvalidOffsetNumber;
    pstate.continuescan = true; /* default assumption */
    pstate.rechecks = 0;
    pstate.targetdistance = 0;
    pstate.nskipadvances = 0;
 
    if (scan->parallel_scan)
    {
        /* allow next/prev page to be read by other worker without delay */
        if (ScanDirectionIsForward(dir))
            _bt_parallel_release(scan, so->currPos.nextPage,
                                 so->currPos.currPage);
        else
            _bt_parallel_release(scan, so->currPos.prevPage,
                                 so->currPos.currPage);
    }
 
    PredicateLockPage(rel, so->currPos.currPage, scan->xs_snapshot);
 
    if (ScanDirectionIsForward(dir))
    {
        /* SK_SEARCHARRAY forward scans must provide high key up front */
        if (arrayKeys)
        {
            if (!P_RIGHTMOST(opaque))
            {
                ItemId      iid = PageGetItemId(page, P_HIKEY);
 
                pstate.finaltup = (IndexTuple) PageGetItem(page, iid);
 
                if (unlikely(so->scanBehind) &&
                    !_bt_scanbehind_checkkeys(scan, dir, pstate.finaltup))
                {
                    /* Schedule another primitive index scan after all */
                    so->currPos.moreRight = false;
                    so->needPrimScan = true;
                    if (scan->parallel_scan)
                        _bt_parallel_primscan_schedule(scan,
                                                       so->currPos.currPage);
                    return false;
                }
            }
 
            so->scanBehind = so->oppositeDirCheck = false;  /* reset */
        }
 
        /*
         * Consider pstate.startikey optimization once the ongoing primitive
         * index scan has already read at least one page
         */
        if (!pstate.firstpage && minoff < maxoff)
            _bt_set_startikey(scan, &pstate);
 
        /* load items[] in ascending order */
        itemIndex = 0;
 
        offnum = Max(offnum, minoff);
 
        while (offnum <= maxoff)
        {
            ItemId      iid = PageGetItemId(page, offnum);
            IndexTuple  itup;
            bool        passes_quals;
 
            /*
             * If the scan specifies not to return killed tuples, then we
             * treat a killed tuple as not passing the qual
             */
            if (ignore_killed_tuples && ItemIdIsDead(iid))
            {
                offnum = OffsetNumberNext(offnum);
                continue;
            }
 
            itup = (IndexTuple) PageGetItem(page, iid);
            Assert(!BTreeTupleIsPivot(itup));
 
            pstate.offnum = offnum;
            passes_quals = _bt_checkkeys(scan, &pstate, arrayKeys,
                                         itup, indnatts);
 
            /*
             * Check if we need to skip ahead to a later tuple (only possible
             * when the scan uses array keys)
             */
            if (arrayKeys && OffsetNumberIsValid(pstate.skip))
            {
                Assert(!passes_quals && pstate.continuescan);
                Assert(offnum < pstate.skip);
                Assert(!pstate.forcenonrequired);
 
                offnum = pstate.skip;
                pstate.skip = InvalidOffsetNumber;
                continue;
            }
 
            if (passes_quals)
            {
                /* tuple passes all scan key conditions */
                if (!BTreeTupleIsPosting(itup))
                {
                    /* Remember it */
                    _bt_saveitem(so, itemIndex, offnum, itup);
                    itemIndex++;
                }
                else
                {
                    int         tupleOffset;
 
                    /* Set up posting list state (and remember first TID) */
                    tupleOffset =
                        _bt_setuppostingitems(so, itemIndex, offnum,
                                              BTreeTupleGetPostingN(itup, 0),
                                              itup);
                    itemIndex++;
 
                    /* Remember all later TIDs (must be at least one) */
                    for (int i = 1; i < BTreeTupleGetNPosting(itup); i++)
                    {
                        _bt_savepostingitem(so, itemIndex, offnum,
                                            BTreeTupleGetPostingN(itup, i),
                                            tupleOffset);
                        itemIndex++;
                    }
                }
            }
            /* When !continuescan, there can't be any more matches, so stop */
            if (!pstate.continuescan)
                break;
 
            offnum = OffsetNumberNext(offnum);
        }
 
        /*
         * We don't need to visit page to the right when the high key
         * indicates that no more matches will be found there.
         *
         * Checking the high key like this works out more often than you might
         * think.  Leaf page splits pick a split point between the two most
         * dissimilar tuples (this is weighed against the need to evenly share
         * free space).  Leaf pages with high key attribute values that can
         * only appear on non-pivot tuples on the right sibling page are
         * common.
         */
        if (pstate.continuescan && !so->scanBehind && !P_RIGHTMOST(opaque))
        {
            ItemId      iid = PageGetItemId(page, P_HIKEY);
            IndexTuple  itup = (IndexTuple) PageGetItem(page, iid);
            int         truncatt;
 
            /* Reset arrays, per _bt_set_startikey contract */
            if (pstate.forcenonrequired)
                _bt_start_array_keys(scan, dir);
            pstate.forcenonrequired = false;
            pstate.startikey = 0;   /* _bt_set_startikey ignores P_HIKEY */
 
            truncatt = BTreeTupleGetNAtts(itup, rel);
            _bt_checkkeys(scan, &pstate, arrayKeys, itup, truncatt);
        }
 
        if (!pstate.continuescan)
            so->currPos.moreRight = false;
 
        Assert(itemIndex <= MaxTIDsPerBTreePage);
        so->currPos.firstItem = 0;
        so->currPos.lastItem = itemIndex - 1;
        so->currPos.itemIndex = 0;
    }
    else
    {
        /* SK_SEARCHARRAY backward scans must provide final tuple up front */
        if (arrayKeys)
        {
            if (minoff <= maxoff && !P_LEFTMOST(opaque))
            {
                ItemId      iid = PageGetItemId(page, minoff);
 
                pstate.finaltup = (IndexTuple) PageGetItem(page, iid);
 
                if (unlikely(so->scanBehind) &&
                    !_bt_scanbehind_checkkeys(scan, dir, pstate.finaltup))
                {
                    /* Schedule another primitive index scan after all */
                    so->currPos.moreLeft = false;
                    so->needPrimScan = true;
                    if (scan->parallel_scan)
                        _bt_parallel_primscan_schedule(scan,
                                                       so->currPos.currPage);
                    return false;
                }
            }
 
            so->scanBehind = so->oppositeDirCheck = false;  /* reset */
        }
 
        /*
         * Consider pstate.startikey optimization once the ongoing primitive
         * index scan has already read at least one page
         */
        if (!pstate.firstpage && minoff < maxoff)
            _bt_set_startikey(scan, &pstate);
 
        /* load items[] in descending order */
        itemIndex = MaxTIDsPerBTreePage;
 
        offnum = Min(offnum, maxoff);
 
        while (offnum >= minoff)
        {
            ItemId      iid = PageGetItemId(page, offnum);
            IndexTuple  itup;
            bool        tuple_alive;
            bool        passes_quals;
 
            /*
             * If the scan specifies not to return killed tuples, then we
             * treat a killed tuple as not passing the qual.  Most of the
             * time, it's a win to not bother examining the tuple's index
             * keys, but just skip to the next tuple (previous, actually,
             * since we're scanning backwards).  However, if this is the first
             * tuple on the page, we do check the index keys, to prevent
             * uselessly advancing to the page to the left.  This is similar
             * to the high key optimization used by forward scans.
             */
            if (ignore_killed_tuples && ItemIdIsDead(iid))
            {
                if (offnum > minoff)
                {
                    offnum = OffsetNumberPrev(offnum);
                    continue;
                }
 
                tuple_alive = false;
            }
            else
                tuple_alive = true;
 
            itup = (IndexTuple) PageGetItem(page, iid);
            Assert(!BTreeTupleIsPivot(itup));
 
            pstate.offnum = offnum;
            if (arrayKeys && offnum == minoff && pstate.forcenonrequired)
            {
                /* Reset arrays, per _bt_set_startikey contract */
                pstate.forcenonrequired = false;
                pstate.startikey = 0;
                _bt_start_array_keys(scan, dir);
            }
            passes_quals = _bt_checkkeys(scan, &pstate, arrayKeys,
                                         itup, indnatts);
 
            if (arrayKeys && so->scanBehind)
            {
                /*
                 * Done scanning this page, but not done with the current
                 * primscan.
                 *
                 * Note: Forward scans don't check this explicitly, since they
                 * prefer to reuse pstate.skip for this instead.
                 */
                Assert(!passes_quals && pstate.continuescan);
                Assert(!pstate.forcenonrequired);
 
                break;
            }
 
            /*
             * Check if we need to skip ahead to a later tuple (only possible
             * when the scan uses array keys)
             */
            if (arrayKeys && OffsetNumberIsValid(pstate.skip))
            {
                Assert(!passes_quals && pstate.continuescan);
                Assert(offnum > pstate.skip);
                Assert(!pstate.forcenonrequired);
 
                offnum = pstate.skip;
                pstate.skip = InvalidOffsetNumber;
                continue;
            }
 
            if (passes_quals && tuple_alive)
            {
                /* tuple passes all scan key conditions */
                if (!BTreeTupleIsPosting(itup))
                {
                    /* Remember it */
                    itemIndex--;
                    _bt_saveitem(so, itemIndex, offnum, itup);
                }
                else
                {
                    uint16      nitems = BTreeTupleGetNPosting(itup);
                    int         tupleOffset;
 
                    /* Set up posting list state (and remember last TID) */
                    itemIndex--;
                    tupleOffset =
                        _bt_setuppostingitems(so, itemIndex, offnum,
                                              BTreeTupleGetPostingN(itup, nitems - 1),
                                              itup);
 
                    /* Remember all prior TIDs (must be at least one) */
                    for (int i = nitems - 2; i >= 0; i--)
                    {
                        itemIndex--;
                        _bt_savepostingitem(so, itemIndex, offnum,
                                            BTreeTupleGetPostingN(itup, i),
                                            tupleOffset);
                    }
                }
            }
            /* When !continuescan, there can't be any more matches, so stop */
            if (!pstate.continuescan)
                break;
 
            offnum = OffsetNumberPrev(offnum);
        }
 
        /*
         * We don't need to visit page to the left when no more matches will
         * be found there
         */
        if (!pstate.continuescan)
            so->currPos.moreLeft = false;
 
        Assert(itemIndex >= 0);
        so->currPos.firstItem = itemIndex;
        so->currPos.lastItem = MaxTIDsPerBTreePage - 1;
        so->currPos.itemIndex = MaxTIDsPerBTreePage - 1;
    }
 
    /*
     * If _bt_set_startikey told us to temporarily treat the scan's keys as
     * nonrequired (possible only during scans with array keys), there must be
     * no lasting consequences for the scan's array keys.  The scan's arrays
     * should now have exactly the same elements as they would have had if the
     * nonrequired behavior had never been used.  (In general, a scan's arrays
     * are expected to track its progress through the index's key space.)
     *
     * We are required (by _bt_set_startikey) to call _bt_checkkeys against
     * pstate.finaltup with pstate.forcenonrequired=false to allow the scan's
     * arrays to recover.  Assert that that step hasn't been missed.
     */
    Assert(!pstate.forcenonrequired);
 
    return (so->currPos.firstItem <= so->currPos.lastItem);
}

References _bt_checkkeys(), _bt_parallel_primscan_schedule(), _bt_parallel_release(), _bt_saveitem(), _bt_savepostingitem(), _bt_scanbehind_checkkeys(), _bt_set_startikey(), _bt_setuppostingitems(), _bt_start_array_keys(), Assert, BTPageGetOpaque, BTPageOpaqueData::btpo_next, BTPageOpaqueData::btpo_prev, BTreeTupleGetNAtts, BTreeTupleGetNPosting(), BTreeTupleGetPostingN(), BTreeTupleIsPivot(), BTreeTupleIsPosting(), BTScanPosIsPinned, BufferGetBlockNumber(), BufferGetPage(), BTReadPageState::continuescan, BTReadPageState::dir, fb(), BTReadPageState::finaltup, BTReadPageState::firstpage, BTReadPageState::forcenonrequired, i, IndexScanDescData::ignore_killed_tuples, IndexScanDescData::indexRelation, IndexRelationGetNumberOfAttributes, InvalidOffsetNumber, ItemIdIsDead, Max, BTReadPageState::maxoff, MaxTIDsPerBTreePage, Min, BTReadPageState::minoff, nitems, BTReadPageState::nskipadvances, BTReadPageState::offnum, OffsetNumberIsValid, OffsetNumberNext, OffsetNumberPrev, IndexScanDescData::opaque, P_FIRSTDATAKEY, P_HIKEY, P_IGNORE, P_LEFTMOST, P_RIGHTMOST, BTReadPageState::page, PageGetItem(), PageGetItemId(), PageGetMaxOffsetNumber(), IndexScanDescData::parallel_scan, PredicateLockPage(), BTReadPageState::rechecks, ScanDirectionIsForward, BTReadPageState::skip, BTReadPageState::startikey, BTReadPageState::targetdistance, unlikely, and IndexScanDescData::xs_snapshot.

Referenced by _bt_readfirstpage(), and _bt_readnextpage().

_bt_rowcompare_cmpresult()

static bool _bt_rowcompare_cmpresult ( ScanKey  subkey, int  cmpresult  )

static

Definition at line 1781 of file nbtreadpage.c.

{
    bool        satisfied;
 
    Assert(subkey->sk_flags & SK_ROW_MEMBER);
 
    switch (subkey->sk_strategy)
    {
        case BTLessStrategyNumber:
            satisfied = (cmpresult < 0);
            break;
        case BTLessEqualStrategyNumber:
            satisfied = (cmpresult <= 0);
            break;
        case BTGreaterEqualStrategyNumber:
            satisfied = (cmpresult >= 0);
            break;
        case BTGreaterStrategyNumber:
            satisfied = (cmpresult > 0);
            break;
        default:
            /* EQ and NE cases aren't allowed here */
            elog(ERROR, "unexpected strategy number %d", subkey->sk_strategy);
            satisfied = false;  /* keep compiler quiet */
            break;
    }
 
    return satisfied;
}

References Assert, BTGreaterEqualStrategyNumber, BTGreaterStrategyNumber, BTLessEqualStrategyNumber, BTLessStrategyNumber, elog, ERROR, fb(), and SK_ROW_MEMBER.

Referenced by _bt_check_rowcompare(), and _bt_set_startikey().

_bt_saveitem()

static void _bt_saveitem ( BTScanOpaque  so, int  itemIndex, OffsetNumber  offnum, IndexTuple  itup  )

static

Definition at line 1032 of file nbtreadpage.c.

{
    BTScanPosItem *currItem = &so->currPos.items[itemIndex];
 
    Assert(!BTreeTupleIsPivot(itup) && !BTreeTupleIsPosting(itup));
 
    currItem->heapTid = itup->t_tid;
    currItem->indexOffset = offnum;
    if (so->currTuples)
    {
        Size        itupsz = IndexTupleSize(itup);
 
        currItem->tupleOffset = so->currPos.nextTupleOffset;
        memcpy(so->currTuples + so->currPos.nextTupleOffset, itup, itupsz);
        so->currPos.nextTupleOffset += MAXALIGN(itupsz);
    }
}

References Assert, BTreeTupleIsPivot(), BTreeTupleIsPosting(), fb(), IndexTupleSize(), MAXALIGN, and IndexTupleData::t_tid.

Referenced by _bt_readpage().

_bt_savepostingitem()

static void _bt_savepostingitem ( BTScanOpaque  so, int  itemIndex, OffsetNumber  offnum, ItemPointer  heapTid, int  tupleOffset  )

inlinestatic

Definition at line 1100 of file nbtreadpage.c.

{
    BTScanPosItem *currItem = &so->currPos.items[itemIndex];
 
    currItem->heapTid = *heapTid;
    currItem->indexOffset = offnum;
 
    /*
     * Have index-only scans return the same base IndexTuple for every TID
     * that originates from the same posting list
     */
    if (so->currTuples)
        currItem->tupleOffset = tupleOffset;
}

References fb(), and BTScanPosItem::heapTid.

Referenced by _bt_readpage().

_bt_scanbehind_checkkeys()

static bool _bt_scanbehind_checkkeys ( IndexScanDesc  scan, ScanDirection  dir, IndexTuple  finaltup  )

static

Definition at line 952 of file nbtreadpage.c.

{
    Relation    rel = scan->indexRelation;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
    int         nfinaltupatts = BTreeTupleGetNAtts(finaltup, rel);
    bool        scanBehind;
 
    Assert(so->numArrayKeys);
 
    if (_bt_tuple_before_array_skeys(scan, dir, finaltup, tupdesc,
                                     nfinaltupatts, false, 0, &scanBehind))
        return false;
 
    /*
     * If scanBehind was set, all of the untruncated attribute values from
     * finaltup that correspond to an array match the array's current element,
     * but there are other keys associated with truncated suffix attributes.
     * Array advancement must have incremented the scan's arrays on the
     * previous page, resulting in a set of array keys that happen to be an
     * exact match for the current page high key's untruncated prefix values.
     *
     * This page definitely doesn't contain tuples that the scan will need to
     * return.  The next page may or may not contain relevant tuples.  Handle
     * this by cutting our losses and starting a new primscan.
     */
    if (scanBehind)
        return false;
 
    if (!so->oppositeDirCheck)
        return true;
 
    return _bt_oppodir_checkkeys(scan, dir, finaltup);
}

References _bt_oppodir_checkkeys(), _bt_tuple_before_array_skeys(), Assert, BTreeTupleGetNAtts, fb(), IndexScanDescData::indexRelation, IndexScanDescData::opaque, and RelationGetDescr.

Referenced by _bt_readpage().

_bt_set_startikey()

static void _bt_set_startikey ( IndexScanDesc  scan, BTReadPageState *  pstate  )

static

Definition at line 593 of file nbtreadpage.c.

{
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
    Relation    rel = scan->indexRelation;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    ItemId      iid;
    IndexTuple  firsttup,
                lasttup;
    int         startikey = 0,
                arrayidx = 0,
                firstchangingattnum;
    bool        start_past_saop_eq = false;
 
    Assert(!so->scanBehind);
    Assert(pstate->minoff < pstate->maxoff);
    Assert(!pstate->firstpage);
    Assert(pstate->startikey == 0);
    Assert(!so->numArrayKeys || pstate->finaltup ||
           P_RIGHTMOST(BTPageGetOpaque(pstate->page)) ||
           P_LEFTMOST(BTPageGetOpaque(pstate->page)));
 
    if (so->numberOfKeys == 0)
        return;
 
    /* minoff is an offset to the lowest non-pivot tuple on the page */
    iid = PageGetItemId(pstate->page, pstate->minoff);
    firsttup = (IndexTuple) PageGetItem(pstate->page, iid);
 
    /* maxoff is an offset to the highest non-pivot tuple on the page */
    iid = PageGetItemId(pstate->page, pstate->maxoff);
    lasttup = (IndexTuple) PageGetItem(pstate->page, iid);
 
    /* Determine the first attribute whose values change on caller's page */
    firstchangingattnum = _bt_keep_natts_fast(rel, firsttup, lasttup);
 
    for (; startikey < so->numberOfKeys; startikey++)
    {
        ScanKey     key = so->keyData + startikey;
        BTArrayKeyInfo *array;
        Datum       firstdatum,
                    lastdatum;
        bool        firstnull,
                    lastnull;
        int32       result;
 
        /*
         * Determine if it's safe to set pstate.startikey to an offset to a
         * key that comes after this key, by examining this key
         */
        if (key->sk_flags & SK_ROW_HEADER)
        {
            /* RowCompare inequality (header key) */
            ScanKey     subkey = (ScanKey) DatumGetPointer(key->sk_argument);
            bool        satisfied = false;
 
            for (;;)
            {
                int         cmpresult;
                bool        firstsatisfies = false;
 
                if (subkey->sk_attno > firstchangingattnum) /* >, not >= */
                    break;      /* unsafe, preceding attr has multiple
                                 * distinct values */
 
                if (subkey->sk_flags & SK_ISNULL)
                    break;      /* unsafe, unsatisfiable NULL subkey arg */
 
                firstdatum = index_getattr(firsttup, subkey->sk_attno,
                                           tupdesc, &firstnull);
                lastdatum = index_getattr(lasttup, subkey->sk_attno,
                                          tupdesc, &lastnull);
 
                if (firstnull || lastnull)
                    break;      /* unsafe, NULL value won't satisfy subkey */
 
                /*
                 * Compare the first tuple's datum for this row compare member
                 */
                cmpresult = DatumGetInt32(FunctionCall2Coll(&subkey->sk_func,
                                                            subkey->sk_collation,
                                                            firstdatum,
                                                            subkey->sk_argument));
                if (subkey->sk_flags & SK_BT_DESC)
                    INVERT_COMPARE_RESULT(cmpresult);
 
                if (cmpresult != 0 || (subkey->sk_flags & SK_ROW_END))
                {
                    firstsatisfies = _bt_rowcompare_cmpresult(subkey,
                                                              cmpresult);
                    if (!firstsatisfies)
                    {
                        /* Unsafe, firstdatum does not satisfy subkey */
                        break;
                    }
                }
 
                /*
                 * Compare the last tuple's datum for this row compare member
                 */
                cmpresult = DatumGetInt32(FunctionCall2Coll(&subkey->sk_func,
                                                            subkey->sk_collation,
                                                            lastdatum,
                                                            subkey->sk_argument));
                if (subkey->sk_flags & SK_BT_DESC)
                    INVERT_COMPARE_RESULT(cmpresult);
 
                if (cmpresult != 0 || (subkey->sk_flags & SK_ROW_END))
                {
                    if (!firstsatisfies)
                    {
                        /*
                         * It's only safe to set startikey beyond the row
                         * compare header key when both firsttup and lasttup
                         * satisfy the key as a whole based on the same
                         * deciding subkey/attribute.  That can't happen now.
                         */
                        break;  /* unsafe */
                    }
 
                    satisfied = _bt_rowcompare_cmpresult(subkey, cmpresult);
                    break;      /* safe iff 'satisfied' is true */
                }
 
                /* Move on to next row member/subkey */
                if (subkey->sk_flags & SK_ROW_END)
                    break;      /* defensive */
                subkey++;
 
                /*
                 * We deliberately don't check if the next subkey has the same
                 * strategy as this iteration's subkey (which happens when
                 * subkeys for both ASC and DESC columns are used together),
                 * nor if any subkey is marked required.  This is safe because
                 * in general all prior index attributes must have only one
                 * distinct value (across all of the tuples on the page) in
                 * order for us to even consider any subkey's attribute.
                 */
            }
 
            if (satisfied)
            {
                /* Safe, row compare satisfied by every tuple on page */
                continue;
            }
 
            break;              /* unsafe */
        }
        if (key->sk_strategy != BTEqualStrategyNumber)
        {
            /*
             * Scalar inequality key.
             *
             * It's definitely safe for _bt_checkkeys to avoid assessing this
             * inequality when the page's first and last non-pivot tuples both
             * satisfy the inequality (since the same must also be true of all
             * the tuples in between these two).
             *
             * Unlike the "=" case, it doesn't matter if this attribute has
             * more than one distinct value (though it _is_ necessary for any
             * and all _prior_ attributes to contain no more than one distinct
             * value amongst all of the tuples from pstate.page).
             */
            if (key->sk_attno > firstchangingattnum)    /* >, not >= */
                break;          /* unsafe, preceding attr has multiple
                                 * distinct values */
 
            firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc, &firstnull);
            lastdatum = index_getattr(lasttup, key->sk_attno, tupdesc, &lastnull);
 
            if (key->sk_flags & SK_ISNULL)
            {
                /* IS NOT NULL key */
                Assert(key->sk_flags & SK_SEARCHNOTNULL);
 
                if (firstnull || lastnull)
                    break;      /* unsafe */
 
                /* Safe, IS NOT NULL key satisfied by every tuple */
                continue;
            }
 
            /* Test firsttup */
            if (firstnull ||
                !DatumGetBool(FunctionCall2Coll(&key->sk_func,
                                                key->sk_collation, firstdatum,
                                                key->sk_argument)))
                break;          /* unsafe */
 
            /* Test lasttup */
            if (lastnull ||
                !DatumGetBool(FunctionCall2Coll(&key->sk_func,
                                                key->sk_collation, lastdatum,
                                                key->sk_argument)))
                break;          /* unsafe */
 
            /* Safe, scalar inequality satisfied by every tuple */
            continue;
        }
 
        /* Some = key (could be a scalar = key, could be an array = key) */
        Assert(key->sk_strategy == BTEqualStrategyNumber);
 
        if (!(key->sk_flags & SK_SEARCHARRAY))
        {
            /*
             * Scalar = key (possibly an IS NULL key).
             *
             * It is unsafe to set pstate.startikey to an ikey beyond this
             * key, unless the = key is satisfied by every possible tuple on
             * the page (possible only when attribute has just one distinct
             * value among all tuples on the page).
             */
            if (key->sk_attno >= firstchangingattnum)
                break;          /* unsafe, multiple distinct attr values */
 
            firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc,
                                       &firstnull);
            if (key->sk_flags & SK_ISNULL)
            {
                /* IS NULL key */
                Assert(key->sk_flags & SK_SEARCHNULL);
 
                if (!firstnull)
                    break;      /* unsafe */
 
                /* Safe, IS NULL key satisfied by every tuple */
                continue;
            }
            if (firstnull ||
                !DatumGetBool(FunctionCall2Coll(&key->sk_func,
                                                key->sk_collation, firstdatum,
                                                key->sk_argument)))
                break;          /* unsafe */
 
            /* Safe, scalar = key satisfied by every tuple */
            continue;
        }
 
        /* = array key (could be a SAOP array, could be a skip array) */
        array = &so->arrayKeys[arrayidx++];
        Assert(array->scan_key == startikey);
        if (array->num_elems != -1)
        {
            /*
             * SAOP array = key.
             *
             * Handle this like we handle scalar = keys (though binary search
             * for a matching element, to avoid relying on key's sk_argument).
             */
            if (key->sk_attno >= firstchangingattnum)
                break;          /* unsafe, multiple distinct attr values */
 
            firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc,
                                       &firstnull);
            _bt_binsrch_array_skey(&so->orderProcs[startikey],
                                   false, NoMovementScanDirection,
                                   firstdatum, firstnull, array, key,
                                   &result);
            if (result != 0)
                break;          /* unsafe */
 
            /* Safe, SAOP = key satisfied by every tuple */
            start_past_saop_eq = true;
            continue;
        }
 
        /*
         * Skip array = key
         */
        Assert(key->sk_flags & SK_BT_SKIP);
        if (array->null_elem)
        {
            /*
             * Non-range skip array = key.
             *
             * Safe, non-range skip array "satisfied" by every tuple on page
             * (safe even when "key->sk_attno > firstchangingattnum").
             */
            continue;
        }
 
        /*
         * Range skip array = key.
         *
         * Handle this like we handle scalar inequality keys (but avoid using
         * key's sk_argument directly, as in the SAOP array case).
         */
        if (key->sk_attno > firstchangingattnum)    /* >, not >= */
            break;              /* unsafe, preceding attr has multiple
                                 * distinct values */
 
        firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc, &firstnull);
        lastdatum = index_getattr(lasttup, key->sk_attno, tupdesc, &lastnull);
 
        /* Test firsttup */
        _bt_binsrch_skiparray_skey(false, ForwardScanDirection,
                                   firstdatum, firstnull, array, key,
                                   &result);
        if (result != 0)
            break;              /* unsafe */
 
        /* Test lasttup */
        _bt_binsrch_skiparray_skey(false, ForwardScanDirection,
                                   lastdatum, lastnull, array, key,
                                   &result);
        if (result != 0)
            break;              /* unsafe */
 
        /* Safe, range skip array satisfied by every tuple on page */
    }
 
    /*
     * Use of forcenonrequired is typically undesirable, since it'll force
     * _bt_readpage caller to read every tuple on the page -- even though, in
     * general, it might well be possible to end the scan on an earlier tuple.
     * However, caller must use forcenonrequired when start_past_saop_eq=true,
     * since the usual required array behavior might fail to roll over to the
     * SAOP array.
     *
     * We always prefer forcenonrequired=true during scans with skip arrays
     * (except on the first page of each primitive index scan), though -- even
     * when "startikey == 0".  That way, _bt_advance_array_keys's low-order
     * key precheck optimization can always be used (unless on the first page
     * of the scan).  It seems slightly preferable to check more tuples when
     * that allows us to do significantly less skip array maintenance.
     */
    pstate->forcenonrequired = (start_past_saop_eq || so->skipScan);
    pstate->startikey = startikey;
 
    /*
     * _bt_readpage caller is required to call _bt_checkkeys against page's
     * finaltup with forcenonrequired=false whenever we initially set
     * forcenonrequired=true.  That way the scan's arrays will reliably track
     * its progress through the index's key space.
     *
     * We don't expect this when _bt_readpage caller has no finaltup due to
     * its page being the rightmost (or the leftmost, during backwards scans).
     * When we see that _bt_readpage has no finaltup, back out of everything.
     */
    Assert(!pstate->forcenonrequired || so->numArrayKeys);
    if (pstate->forcenonrequired && !pstate->finaltup)
    {
        pstate->forcenonrequired = false;
        pstate->startikey = 0;
    }
}

References _bt_binsrch_array_skey(), _bt_binsrch_skiparray_skey(), _bt_keep_natts_fast(), _bt_rowcompare_cmpresult(), Assert, BTEqualStrategyNumber, BTPageGetOpaque, DatumGetBool(), DatumGetInt32(), DatumGetPointer(), fb(), BTReadPageState::finaltup, BTReadPageState::firstpage, BTReadPageState::forcenonrequired, ForwardScanDirection, FunctionCall2Coll(), index_getattr(), IndexScanDescData::indexRelation, INVERT_COMPARE_RESULT, BTReadPageState::maxoff, BTReadPageState::minoff, NoMovementScanDirection, BTArrayKeyInfo::null_elem, BTArrayKeyInfo::num_elems, IndexScanDescData::opaque, P_LEFTMOST, P_RIGHTMOST, BTReadPageState::page, PageGetItem(), PageGetItemId(), RelationGetDescr, BTArrayKeyInfo::scan_key, SK_BT_DESC, SK_BT_SKIP, SK_ISNULL, SK_ROW_END, SK_ROW_HEADER, SK_SEARCHARRAY, SK_SEARCHNOTNULL, SK_SEARCHNULL, and BTReadPageState::startikey.

Referenced by _bt_readpage().

_bt_setuppostingitems()

static int _bt_setuppostingitems ( BTScanOpaque  so, int  itemIndex, OffsetNumber  offnum, const ItemPointerData *  heapTid, IndexTuple  itup  )

static

Definition at line 1062 of file nbtreadpage.c.

{
    BTScanPosItem *currItem = &so->currPos.items[itemIndex];
 
    Assert(BTreeTupleIsPosting(itup));
 
    currItem->heapTid = *heapTid;
    currItem->indexOffset = offnum;
    if (so->currTuples)
    {
        /* Save base IndexTuple (truncate posting list) */
        IndexTuple  base;
        Size        itupsz = BTreeTupleGetPostingOffset(itup);
 
        itupsz = MAXALIGN(itupsz);
        currItem->tupleOffset = so->currPos.nextTupleOffset;
        base = (IndexTuple) (so->currTuples + so->currPos.nextTupleOffset);
        memcpy(base, itup, itupsz);
        /* Defensively reduce work area index tuple header size */
        base->t_info &= ~INDEX_SIZE_MASK;
        base->t_info |= itupsz;
        so->currPos.nextTupleOffset += itupsz;
 
        return currItem->tupleOffset;
    }
 
    return 0;
}

References Assert, BTreeTupleGetPostingOffset(), BTreeTupleIsPosting(), fb(), MAXALIGN, and IndexTupleData::t_info.

Referenced by _bt_readpage().

_bt_skiparray_set_element()

static void _bt_skiparray_set_element ( Relation  rel, ScanKey  skey, BTArrayKeyInfo *  array, int32  set_elem_result, Datum  tupdatum, bool  tupnull  )

static

Definition at line 3273 of file nbtreadpage.c.

{
    Assert(skey->sk_flags & SK_BT_SKIP);
    Assert(skey->sk_flags & SK_SEARCHARRAY);
 
    if (set_elem_result)
    {
        /* tupdatum/tupnull is out of the range of the skip array */
        Assert(!array->null_elem);
 
        _bt_array_set_low_or_high(rel, skey, array, set_elem_result < 0);
        return;
    }
 
    /* Advance skip array to tupdatum (or tupnull) value */
    if (unlikely(tupnull))
    {
        _bt_skiparray_set_isnull(rel, skey, array);
        return;
    }
 
    /* Free memory previously allocated for sk_argument if needed */
    if (!array->attbyval && skey->sk_argument)
        pfree(DatumGetPointer(skey->sk_argument));
 
    /* tupdatum becomes new sk_argument/new current element */
    skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL |
                        SK_BT_MINVAL | SK_BT_MAXVAL |
                        SK_BT_NEXT | SK_BT_PRIOR);
    skey->sk_argument = datumCopy(tupdatum, array->attbyval, array->attlen);
}

References _bt_array_set_low_or_high(), _bt_skiparray_set_isnull(), Assert, BTArrayKeyInfo::attbyval, BTArrayKeyInfo::attlen, datumCopy(), DatumGetPointer(), fb(), BTArrayKeyInfo::null_elem, pfree(), SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_PRIOR, SK_BT_SKIP, SK_ISNULL, SK_SEARCHARRAY, SK_SEARCHNULL, and unlikely.

Referenced by _bt_advance_array_keys().

_bt_skiparray_set_isnull()

static void _bt_skiparray_set_isnull ( Relation  rel, ScanKey  skey, BTArrayKeyInfo *  array  )

static

Definition at line 3310 of file nbtreadpage.c.

{
    Assert(skey->sk_flags & SK_BT_SKIP);
    Assert(skey->sk_flags & SK_SEARCHARRAY);
    Assert(array->null_elem && !array->low_compare && !array->high_compare);
 
    /* Free memory previously allocated for sk_argument if needed */
    if (!array->attbyval && skey->sk_argument)
        pfree(DatumGetPointer(skey->sk_argument));
 
    /* NULL becomes new sk_argument/new current element */
    skey->sk_argument = (Datum) 0;
    skey->sk_flags &= ~(SK_BT_MINVAL | SK_BT_MAXVAL |
                        SK_BT_NEXT | SK_BT_PRIOR);
    skey->sk_flags |= (SK_SEARCHNULL | SK_ISNULL);
}

References Assert, BTArrayKeyInfo::attbyval, DatumGetPointer(), fb(), BTArrayKeyInfo::high_compare, BTArrayKeyInfo::low_compare, BTArrayKeyInfo::null_elem, pfree(), SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_PRIOR, SK_BT_SKIP, SK_ISNULL, SK_SEARCHARRAY, and SK_SEARCHNULL.

Referenced by _bt_array_decrement(), _bt_array_increment(), and _bt_skiparray_set_element().

_bt_start_array_keys()

void _bt_start_array_keys	(	IndexScanDesc	scan,
		ScanDirection	dir
	)

Definition at line 537 of file nbtreadpage.c.

{
    Relation    rel = scan->indexRelation;
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
 
    Assert(so->numArrayKeys);
    Assert(so->qual_ok);
 
    for (int i = 0; i < so->numArrayKeys; i++)
    {
        BTArrayKeyInfo *array = &so->arrayKeys[i];
        ScanKey     skey = &so->keyData[array->scan_key];
 
        Assert(skey->sk_flags & SK_SEARCHARRAY);
 
        _bt_array_set_low_or_high(rel, skey, array,
                                  ScanDirectionIsForward(dir));
    }
    so->scanBehind = so->oppositeDirCheck = false;  /* reset */
}

References _bt_array_set_low_or_high(), Assert, fb(), i, IndexScanDescData::indexRelation, IndexScanDescData::opaque, BTArrayKeyInfo::scan_key, ScanDirectionIsForward, and SK_SEARCHARRAY.

Referenced by _bt_advance_array_keys_increment(), _bt_first(), _bt_readpage(), and btrestrpos().

_bt_tuple_before_array_skeys()

static bool _bt_tuple_before_array_skeys ( IndexScanDesc  scan, ScanDirection  dir, IndexTuple  tuple, TupleDesc  tupdesc, int  tupnatts, bool  readpagetup, int  sktrig, bool *  scanBehind  )

static

Definition at line 1854 of file nbtreadpage.c.

{
    BTScanOpaque so = (BTScanOpaque) scan->opaque;
 
    Assert(so->numArrayKeys);
    Assert(so->numberOfKeys);
    Assert(sktrig == 0 || readpagetup);
    Assert(!readpagetup || scanBehind == NULL);
 
    if (scanBehind)
        *scanBehind = false;
 
    for (int ikey = sktrig; ikey < so->numberOfKeys; ikey++)
    {
        ScanKey     cur = so->keyData + ikey;
        Datum       tupdatum;
        bool        tupnull;
        int32       result;
 
        /* readpagetup calls require one ORDER proc comparison (at most) */
        Assert(!readpagetup || ikey == sktrig);
 
        /*
         * Once we reach a non-required scan key, we're completely done.
         *
         * Note: we deliberately don't consider the scan direction here.
         * _bt_advance_array_keys caller requires that we track *scanBehind
         * without concern for scan direction.
         */
        if ((cur->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)) == 0)
        {
            Assert(!readpagetup);
            Assert(ikey > sktrig || ikey == 0);
            return false;
        }
 
        if (cur->sk_attno > tupnatts)
        {
            Assert(!readpagetup);
 
            /*
             * When we reach a high key's truncated attribute, assume that the
             * tuple attribute's value is >= the scan's equality constraint
             * scan keys (but set *scanBehind to let interested callers know
             * that a truncated attribute might have affected our answer).
             */
            if (scanBehind)
                *scanBehind = true;
 
            return false;
        }
 
        /*
         * Deal with inequality strategy scan keys that _bt_check_compare set
         * continuescan=false for
         */
        if (cur->sk_strategy != BTEqualStrategyNumber)
        {
            /*
             * When _bt_check_compare indicated that a required inequality
             * scan key wasn't satisfied, there's no need to verify anything;
             * caller always calls _bt_advance_array_keys with this sktrig.
             */
            if (readpagetup)
                return false;
 
            /*
             * Otherwise we can't give up, since we must check all required
             * scan keys (required in either direction) in order to correctly
             * track *scanBehind for caller
             */
            continue;
        }
 
        tupdatum = index_getattr(tuple, cur->sk_attno, tupdesc, &tupnull);
 
        if (likely(!(cur->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL))))
        {
            /* Scankey has a valid/comparable sk_argument value */
            result = _bt_compare_array_skey(&so->orderProcs[ikey],
                                            tupdatum, tupnull,
                                            cur->sk_argument, cur);
 
            if (result == 0)
            {
                /*
                 * Interpret result in a way that takes NEXT/PRIOR into
                 * account
                 */
                if (cur->sk_flags & SK_BT_NEXT)
                    result = -1;
                else if (cur->sk_flags & SK_BT_PRIOR)
                    result = 1;
 
                Assert(result == 0 || (cur->sk_flags & SK_BT_SKIP));
            }
        }
        else
        {
            BTArrayKeyInfo *array = NULL;
 
            /*
             * Current array element/array = scan key value is a sentinel
             * value that represents the lowest (or highest) possible value
             * that's still within the range of the array.
             *
             * Like _bt_first, we only see MINVAL keys during forwards scans
             * (and similarly only see MAXVAL keys during backwards scans).
             * Even if the scan's direction changes, we'll stop at some higher
             * order key before we can ever reach any MAXVAL (or MINVAL) keys.
             * (However, unlike _bt_first we _can_ get to keys marked either
             * NEXT or PRIOR, regardless of the scan's current direction.)
             */
            Assert(ScanDirectionIsForward(dir) ?
                   !(cur->sk_flags & SK_BT_MAXVAL) :
                   !(cur->sk_flags & SK_BT_MINVAL));
 
            /*
             * There are no valid sk_argument values in MINVAL/MAXVAL keys.
             * Check if tupdatum is within the range of skip array instead.
             */
            for (int arrayidx = 0; arrayidx < so->numArrayKeys; arrayidx++)
            {
                array = &so->arrayKeys[arrayidx];
                if (array->scan_key == ikey)
                    break;
            }
 
            _bt_binsrch_skiparray_skey(false, dir, tupdatum, tupnull,
                                       array, cur, &result);
 
            if (result == 0)
            {
                /*
                 * tupdatum satisfies both low_compare and high_compare, so
                 * it's time to advance the array keys.
                 *
                 * Note: It's possible that the skip array will "advance" from
                 * its MINVAL (or MAXVAL) representation to an alternative,
                 * logically equivalent representation of the same value: a
                 * representation where the = key gets a valid datum in its
                 * sk_argument.  This is only possible when low_compare uses
                 * the >= strategy (or high_compare uses the <= strategy).
                 */
                return false;
            }
        }
 
        /*
         * Does this comparison indicate that caller must _not_ advance the
         * scan's arrays just yet?
         */
        if ((ScanDirectionIsForward(dir) && result < 0) ||
            (ScanDirectionIsBackward(dir) && result > 0))
            return true;
 
        /*
         * Does this comparison indicate that caller should now advance the
         * scan's arrays?  (Must be if we get here during a readpagetup call.)
         */
        if (readpagetup || result != 0)
        {
            Assert(result != 0);
            return false;
        }
 
        /*
         * Inconclusive -- need to check later scan keys, too.
         *
         * This must be a finaltup precheck, or a call made from an assertion.
         */
        Assert(result == 0);
    }
 
    Assert(!readpagetup);
 
    return false;
}

References _bt_binsrch_skiparray_skey(), _bt_compare_array_skey(), Assert, BTEqualStrategyNumber, cur, fb(), index_getattr(), likely, IndexScanDescData::opaque, BTArrayKeyInfo::scan_key, ScanDirectionIsBackward, ScanDirectionIsForward, SK_BT_MAXVAL, SK_BT_MINVAL, SK_BT_NEXT, SK_BT_PRIOR, SK_BT_REQBKWD, SK_BT_REQFWD, and SK_BT_SKIP.

Referenced by _bt_advance_array_keys(), _bt_checkkeys(), _bt_checkkeys_look_ahead(), and _bt_scanbehind_checkkeys().