ginutil.c

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/*-------------------------------------------------------------------------
 *
 * ginutil.c
 *    Utility routines for the Postgres inverted index access method.
 *
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *          src/backend/access/gin/ginutil.c
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "access/gin_private.h"
#include "access/ginxlog.h"
#include "access/reloptions.h"
#include "access/xloginsert.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_type.h"
#include "commands/progress.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "storage/indexfsm.h"
#include "utils/builtins.h"
#include "utils/index_selfuncs.h"
#include "utils/rel.h"
#include "utils/typcache.h"
#include "lib/qunique.h"
 
 
/*
 * GIN handler function: return IndexAmRoutine with access method parameters
 * and callbacks.
 */
Datum
ginhandler(PG_FUNCTION_ARGS)
{
    static const IndexAmRoutine amroutine = {
        .type = T_IndexAmRoutine,
        .amstrategies = 0,
        .amsupport = GINNProcs,
        .amoptsprocnum = GIN_OPTIONS_PROC,
        .amcanorder = false,
        .amcanorderbyop = false,
        .amcanhash = false,
        .amconsistentequality = false,
        .amconsistentordering = false,
        .amcanbackward = false,
        .amcanunique = false,
        .amcanmulticol = true,
        .amoptionalkey = true,
        .amsearcharray = false,
        .amsearchnulls = false,
        .amstorage = true,
        .amclusterable = false,
        .ampredlocks = true,
        .amcanparallel = false,
        .amcanbuildparallel = true,
        .amcaninclude = false,
        .amusemaintenanceworkmem = true,
        .amsummarizing = false,
        .amparallelvacuumoptions =
        VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP,
        .amkeytype = InvalidOid,
 
        .ambuild = ginbuild,
        .ambuildempty = ginbuildempty,
        .aminsert = gininsert,
        .aminsertcleanup = NULL,
        .ambulkdelete = ginbulkdelete,
        .amvacuumcleanup = ginvacuumcleanup,
        .amcanreturn = NULL,
        .amcostestimate = gincostestimate,
        .amgettreeheight = NULL,
        .amoptions = ginoptions,
        .amproperty = NULL,
        .ambuildphasename = ginbuildphasename,
        .amvalidate = ginvalidate,
        .amadjustmembers = ginadjustmembers,
        .ambeginscan = ginbeginscan,
        .amrescan = ginrescan,
        .amgettuple = NULL,
        .amgetbitmap = gingetbitmap,
        .amendscan = ginendscan,
        .ammarkpos = NULL,
        .amrestrpos = NULL,
        .amestimateparallelscan = NULL,
        .aminitparallelscan = NULL,
        .amparallelrescan = NULL,
    };
 
    PG_RETURN_POINTER(&amroutine);
}
 
/*
 * initGinState: fill in an empty GinState struct to describe the index
 *
 * Note: assorted subsidiary data is allocated in the CurrentMemoryContext.
 */
void
initGinState(GinState *state, Relation index)
{
    TupleDesc   origTupdesc = RelationGetDescr(index);
    int         i;
 
    MemSet(state, 0, sizeof(GinState));
 
    state->index = index;
    state->oneCol = (origTupdesc->natts == 1);
    state->origTupdesc = origTupdesc;
 
    for (i = 0; i < origTupdesc->natts; i++)
    {
        Form_pg_attribute attr = TupleDescAttr(origTupdesc, i);
 
        if (state->oneCol)
            state->tupdesc[i] = state->origTupdesc;
        else
        {
            state->tupdesc[i] = CreateTemplateTupleDesc(2);
 
            TupleDescInitEntry(state->tupdesc[i], (AttrNumber) 1, NULL,
                               INT2OID, -1, 0);
            TupleDescInitEntry(state->tupdesc[i], (AttrNumber) 2, NULL,
                               attr->atttypid,
                               attr->atttypmod,
                               attr->attndims);
            TupleDescInitEntryCollation(state->tupdesc[i], (AttrNumber) 2,
                                        attr->attcollation);
            TupleDescFinalize(state->tupdesc[i]);
        }
 
        /*
         * If the compare proc isn't specified in the opclass definition, look
         * up the index key type's default btree comparator.
         */
        if (index_getprocid(index, i + 1, GIN_COMPARE_PROC) != InvalidOid)
        {
            fmgr_info_copy(&(state->compareFn[i]),
                           index_getprocinfo(index, i + 1, GIN_COMPARE_PROC),
                           CurrentMemoryContext);
        }
        else
        {
            TypeCacheEntry *typentry;
 
            typentry = lookup_type_cache(attr->atttypid,
                                         TYPECACHE_CMP_PROC_FINFO);
            if (!OidIsValid(typentry->cmp_proc_finfo.fn_oid))
                ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_FUNCTION),
                         errmsg("could not identify a comparison function for type %s",
                                format_type_be(attr->atttypid))));
            fmgr_info_copy(&(state->compareFn[i]),
                           &(typentry->cmp_proc_finfo),
                           CurrentMemoryContext);
        }
 
        /* Opclass must always provide extract procs */
        fmgr_info_copy(&(state->extractValueFn[i]),
                       index_getprocinfo(index, i + 1, GIN_EXTRACTVALUE_PROC),
                       CurrentMemoryContext);
        fmgr_info_copy(&(state->extractQueryFn[i]),
                       index_getprocinfo(index, i + 1, GIN_EXTRACTQUERY_PROC),
                       CurrentMemoryContext);
 
        /*
         * Check opclass capability to do tri-state or binary logic consistent
         * check.
         */
        if (index_getprocid(index, i + 1, GIN_TRICONSISTENT_PROC) != InvalidOid)
        {
            fmgr_info_copy(&(state->triConsistentFn[i]),
                           index_getprocinfo(index, i + 1, GIN_TRICONSISTENT_PROC),
                           CurrentMemoryContext);
        }
 
        if (index_getprocid(index, i + 1, GIN_CONSISTENT_PROC) != InvalidOid)
        {
            fmgr_info_copy(&(state->consistentFn[i]),
                           index_getprocinfo(index, i + 1, GIN_CONSISTENT_PROC),
                           CurrentMemoryContext);
        }
 
        if (state->consistentFn[i].fn_oid == InvalidOid &&
            state->triConsistentFn[i].fn_oid == InvalidOid)
        {
            elog(ERROR, "missing GIN support function (%d or %d) for attribute %d of index \"%s\"",
                 GIN_CONSISTENT_PROC, GIN_TRICONSISTENT_PROC,
                 i + 1, RelationGetRelationName(index));
        }
 
        /*
         * Check opclass capability to do partial match.
         */
        if (index_getprocid(index, i + 1, GIN_COMPARE_PARTIAL_PROC) != InvalidOid)
        {
            fmgr_info_copy(&(state->comparePartialFn[i]),
                           index_getprocinfo(index, i + 1, GIN_COMPARE_PARTIAL_PROC),
                           CurrentMemoryContext);
            state->canPartialMatch[i] = true;
        }
        else
        {
            state->canPartialMatch[i] = false;
        }
 
        /*
         * If the index column has a specified collation, we should honor that
         * while doing comparisons.  However, we may have a collatable storage
         * type for a noncollatable indexed data type (for instance, hstore
         * uses text index entries).  If there's no index collation then
         * specify default collation in case the support functions need
         * collation.  This is harmless if the support functions don't care
         * about collation, so we just do it unconditionally.  (We could
         * alternatively call get_typcollation, but that seems like expensive
         * overkill --- there aren't going to be any cases where a GIN storage
         * type has a nondefault collation.)
         */
        if (OidIsValid(index->rd_indcollation[i]))
            state->supportCollation[i] = index->rd_indcollation[i];
        else
            state->supportCollation[i] = DEFAULT_COLLATION_OID;
    }
}
 
/*
 * Extract attribute (column) number of stored entry from GIN tuple
 */
OffsetNumber
gintuple_get_attrnum(GinState *ginstate, IndexTuple tuple)
{
    OffsetNumber colN;
 
    if (ginstate->oneCol)
    {
        /* column number is not stored explicitly */
        colN = FirstOffsetNumber;
    }
    else
    {
        Datum       res;
        bool        isnull;
 
        /*
         * First attribute is always int16, so we can safely use any tuple
         * descriptor to obtain first attribute of tuple
         */
        res = index_getattr(tuple, FirstOffsetNumber, ginstate->tupdesc[0],
                            &isnull);
        Assert(!isnull);
 
        colN = DatumGetUInt16(res);
        Assert(colN >= FirstOffsetNumber && colN <= ginstate->origTupdesc->natts);
    }
 
    return colN;
}
 
/*
 * Extract stored datum (and possible null category) from GIN tuple
 */
Datum
gintuple_get_key(GinState *ginstate, IndexTuple tuple,
                 GinNullCategory *category)
{
    Datum       res;
    bool        isnull;
 
    if (ginstate->oneCol)
    {
        /*
         * Single column index doesn't store attribute numbers in tuples
         */
        res = index_getattr(tuple, FirstOffsetNumber, ginstate->origTupdesc,
                            &isnull);
    }
    else
    {
        /*
         * Since the datum type depends on which index column it's from, we
         * must be careful to use the right tuple descriptor here.
         */
        OffsetNumber colN = gintuple_get_attrnum(ginstate, tuple);
 
        res = index_getattr(tuple, OffsetNumberNext(FirstOffsetNumber),
                            ginstate->tupdesc[colN - 1],
                            &isnull);
    }
 
    if (isnull)
        *category = GinGetNullCategory(tuple, ginstate);
    else
        *category = GIN_CAT_NORM_KEY;
 
    return res;
}
 
/*
 * Allocate a new page (either by recycling, or by extending the index file)
 * The returned buffer is already pinned and exclusive-locked
 * Caller is responsible for initializing the page by calling GinInitBuffer
 */
Buffer
GinNewBuffer(Relation index)
{
    Buffer      buffer;
 
    /* First, try to get a page from FSM */
    for (;;)
    {
        BlockNumber blkno = GetFreeIndexPage(index);
 
        if (blkno == InvalidBlockNumber)
            break;
 
        buffer = ReadBuffer(index, blkno);
 
        /*
         * We have to guard against the possibility that someone else already
         * recycled this page; the buffer may be locked if so.
         */
        if (ConditionalLockBuffer(buffer))
        {
            if (GinPageIsRecyclable(BufferGetPage(buffer)))
                return buffer;  /* OK to use */
 
            LockBuffer(buffer, GIN_UNLOCK);
        }
 
        /* Can't use it, so release buffer and try again */
        ReleaseBuffer(buffer);
    }
 
    /* Must extend the file */
    buffer = ExtendBufferedRel(BMR_REL(index), MAIN_FORKNUM, NULL,
                               EB_LOCK_FIRST);
 
    return buffer;
}
 
void
GinInitPage(Page page, uint32 f, Size pageSize)
{
    GinPageOpaque opaque;
 
    PageInit(page, pageSize, sizeof(GinPageOpaqueData));
 
    opaque = GinPageGetOpaque(page);
    opaque->flags = f;
    opaque->rightlink = InvalidBlockNumber;
}
 
void
GinInitBuffer(Buffer b, uint32 f)
{
    GinInitPage(BufferGetPage(b), f, BufferGetPageSize(b));
}
 
void
GinInitMetabuffer(Buffer b)
{
    GinMetaPageData *metadata;
    Page        page = BufferGetPage(b);
 
    GinInitPage(page, GIN_META, BufferGetPageSize(b));
 
    metadata = GinPageGetMeta(page);
 
    metadata->head = metadata->tail = InvalidBlockNumber;
    metadata->tailFreeSize = 0;
    metadata->nPendingPages = 0;
    metadata->nPendingHeapTuples = 0;
    metadata->nTotalPages = 0;
    metadata->nEntryPages = 0;
    metadata->nDataPages = 0;
    metadata->nEntries = 0;
    metadata->ginVersion = GIN_CURRENT_VERSION;
 
    /*
     * Set pd_lower just past the end of the metadata.  This is essential,
     * because without doing so, metadata will be lost if xlog.c compresses
     * the page.
     */
    ((PageHeader) page)->pd_lower =
        ((char *) metadata + sizeof(GinMetaPageData)) - (char *) page;
}
 
/*
 * Support for sorting key datums and detecting duplicates in
 * ginExtractEntries
 */
typedef struct
{
    FmgrInfo   *cmpDatumFunc;
    Oid         collation;
    bool        haveDups;
} cmpEntriesArg;
 
static int
cmpEntries(const void *a, const void *b, void *arg)
{
    const Datum *aa = (const Datum *) a;
    const Datum *bb = (const Datum *) b;
    cmpEntriesArg *data = (cmpEntriesArg *) arg;
    int         res;
 
    res = DatumGetInt32(FunctionCall2Coll(data->cmpDatumFunc,
                                          data->collation,
                                          *aa, *bb));
 
    /*
     * Detect if we have any duplicates.  If there are equal keys, qsort must
     * compare them at some point, else it wouldn't know whether one should go
     * before or after the other.
     */
    if (res == 0)
        data->haveDups = true;
 
    return res;
}
 
#define ST_SORT qsort_arg_entries
#define ST_ELEMENT_TYPE Datum
#define ST_COMPARE_ARG_TYPE cmpEntriesArg
#define ST_COMPARE(a, b, arg) cmpEntries(a, b, arg)
#define ST_SCOPE static
#define ST_DEFINE
#define ST_DECLARE
#include "lib/sort_template.h"
 
/*
 * Extract the index key values from an indexable item
 *
 * The resulting key values are sorted, and any duplicates are removed.
 * This avoids generating redundant index entries.
 */
Datum *
ginExtractEntries(GinState *ginstate, OffsetNumber attnum,
                  Datum value, bool isNull,
                  int32 *nentries_p, GinNullCategory **categories_p)
{
    Datum      *entries;
    bool       *nullFlags;
    GinNullCategory *categories;
    bool        hasNull;
    int32       nentries;
 
    /*
     * We don't call the extractValueFn on a null item.  Instead generate a
     * placeholder.
     */
    if (isNull)
    {
        *nentries_p = 1;
        entries = palloc_object(Datum);
        entries[0] = (Datum) 0;
        *categories_p = palloc_object(GinNullCategory);
        (*categories_p)[0] = GIN_CAT_NULL_ITEM;
        return entries;
    }
 
    /* OK, call the opclass's extractValueFn */
    nullFlags = NULL;           /* in case extractValue doesn't set it */
    nentries = 0;
    entries = (Datum *)
        DatumGetPointer(FunctionCall3Coll(&ginstate->extractValueFn[attnum - 1],
                                          ginstate->supportCollation[attnum - 1],
                                          value,
                                          PointerGetDatum(&nentries),
                                          PointerGetDatum(&nullFlags)));
 
    /*
     * Generate a placeholder if the item contained no keys.
     */
    if (entries == NULL || nentries <= 0)
    {
        *nentries_p = 1;
        entries = palloc_object(Datum);
        entries[0] = (Datum) 0;
        *categories_p = palloc_object(GinNullCategory);
        (*categories_p)[0] = GIN_CAT_EMPTY_ITEM;
        return entries;
    }
 
    /*
     * Scan the items for any NULLs.  All NULLs are considered equal, so we
     * just need to check and remember if there are any.  We remove them from
     * the array here, and after deduplication, put back one NULL entry to
     * represent them all.
     */
    hasNull = false;
    if (nullFlags)
    {
        int32       numNonNulls = 0;
 
        for (int32 i = 0; i < nentries; i++)
        {
            if (nullFlags[i])
                hasNull = true;
            else
            {
                entries[numNonNulls] = entries[i];
                numNonNulls++;
            }
        }
        nentries = numNonNulls;
    }
 
    /*
     * If there's more than one key, sort and unique-ify.
     *
     * XXX Using qsort here is notationally painful, and the overhead is
     * pretty bad too.  For small numbers of keys it'd likely be better to use
     * a simple insertion sort.
     */
    if (nentries > 1)
    {
        cmpEntriesArg arg;
 
        arg.cmpDatumFunc = &ginstate->compareFn[attnum - 1];
        arg.collation = ginstate->supportCollation[attnum - 1];
        arg.haveDups = false;
 
        qsort_arg_entries(entries, nentries, &arg);
 
        if (arg.haveDups)
            nentries = qunique_arg(entries, nentries, sizeof(Datum), cmpEntries, &arg);
    }
 
    /*
     * Create GinNullCategory representation.
     */
    StaticAssertStmt(GIN_CAT_NORM_KEY == 0, "Assuming GIN_CAT_NORM_KEY=0");
    categories = palloc0_array(GinNullCategory, nentries + (hasNull ? 1 : 0));
 
    /* Put back a NULL entry, if there were any */
    if (hasNull)
    {
        entries[nentries] = (Datum) 0;
        categories[nentries] = GIN_CAT_NULL_KEY;
        nentries++;
    }
 
    *nentries_p = nentries;
    *categories_p = categories;
    return entries;
}
 
bytea *
ginoptions(Datum reloptions, bool validate)
{
    static const relopt_parse_elt tab[] = {
        {"fastupdate", RELOPT_TYPE_BOOL, offsetof(GinOptions, useFastUpdate)},
        {"gin_pending_list_limit", RELOPT_TYPE_INT, offsetof(GinOptions,
                                                             pendingListCleanupSize)}
    };
 
    return (bytea *) build_reloptions(reloptions, validate,
                                      RELOPT_KIND_GIN,
                                      sizeof(GinOptions),
                                      tab, lengthof(tab));
}
 
/*
 * Fetch index's statistical data into *stats
 *
 * Note: in the result, nPendingPages can be trusted to be up-to-date,
 * as can ginVersion; but the other fields are as of the last VACUUM.
 */
void
ginGetStats(Relation index, GinStatsData *stats)
{
    Buffer      metabuffer;
    Page        metapage;
    GinMetaPageData *metadata;
 
    metabuffer = ReadBuffer(index, GIN_METAPAGE_BLKNO);
    LockBuffer(metabuffer, GIN_SHARE);
    metapage = BufferGetPage(metabuffer);
    metadata = GinPageGetMeta(metapage);
 
    stats->nPendingPages = metadata->nPendingPages;
    stats->nTotalPages = metadata->nTotalPages;
    stats->nEntryPages = metadata->nEntryPages;
    stats->nDataPages = metadata->nDataPages;
    stats->nEntries = metadata->nEntries;
    stats->ginVersion = metadata->ginVersion;
 
    UnlockReleaseBuffer(metabuffer);
}
 
/*
 * Write the given statistics to the index's metapage
 *
 * Note: nPendingPages and ginVersion are *not* copied over
 */
void
ginUpdateStats(Relation index, const GinStatsData *stats, bool is_build)
{
    Buffer      metabuffer;
    Page        metapage;
    GinMetaPageData *metadata;
 
    metabuffer = ReadBuffer(index, GIN_METAPAGE_BLKNO);
    LockBuffer(metabuffer, GIN_EXCLUSIVE);
    metapage = BufferGetPage(metabuffer);
    metadata = GinPageGetMeta(metapage);
 
    START_CRIT_SECTION();
 
    metadata->nTotalPages = stats->nTotalPages;
    metadata->nEntryPages = stats->nEntryPages;
    metadata->nDataPages = stats->nDataPages;
    metadata->nEntries = stats->nEntries;
 
    /*
     * Set pd_lower just past the end of the metadata.  This is essential,
     * because without doing so, metadata will be lost if xlog.c compresses
     * the page.  (We must do this here because pre-v11 versions of PG did not
     * set the metapage's pd_lower correctly, so a pg_upgraded index might
     * contain the wrong value.)
     */
    ((PageHeader) metapage)->pd_lower =
        ((char *) metadata + sizeof(GinMetaPageData)) - (char *) metapage;
 
    MarkBufferDirty(metabuffer);
 
    if (RelationNeedsWAL(index) && !is_build)
    {
        XLogRecPtr  recptr;
        ginxlogUpdateMeta data;
 
        data.locator = index->rd_locator;
        data.ntuples = 0;
        data.newRightlink = data.prevTail = InvalidBlockNumber;
        memcpy(&data.metadata, metadata, sizeof(GinMetaPageData));
 
        XLogBeginInsert();
        XLogRegisterData(&data, sizeof(ginxlogUpdateMeta));
        XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT | REGBUF_STANDARD);
 
        recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_UPDATE_META_PAGE);
        PageSetLSN(metapage, recptr);
    }
 
    END_CRIT_SECTION();
 
    UnlockReleaseBuffer(metabuffer);
}
 
/*
 *  ginbuildphasename() -- Return name of index build phase.
 */
char *
ginbuildphasename(int64 phasenum)
{
    switch (phasenum)
    {
        case PROGRESS_CREATEIDX_SUBPHASE_INITIALIZE:
            return "initializing";
        case PROGRESS_GIN_PHASE_INDEXBUILD_TABLESCAN:
            return "scanning table";
        case PROGRESS_GIN_PHASE_PERFORMSORT_1:
            return "sorting tuples (workers)";
        case PROGRESS_GIN_PHASE_MERGE_1:
            return "merging tuples (workers)";
        case PROGRESS_GIN_PHASE_PERFORMSORT_2:
            return "sorting tuples";
        case PROGRESS_GIN_PHASE_MERGE_2:
            return "merging tuples";
        default:
            return NULL;
    }
}