pquery.c File Reference

#include "postgres.h"
#include <limits.h>
#include "access/xact.h"
#include "commands/prepare.h"
#include "executor/tstoreReceiver.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "tcop/pquery.h"
#include "tcop/utility.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"

Include dependency graph for pquery.c:

Go to the source code of this file.

Functions
static void	ProcessQuery (PlannedStmt *plan, const char *sourceText, ParamListInfo params, QueryEnvironment *queryEnv, DestReceiver *dest, QueryCompletion *qc)
static void	FillPortalStore (Portal portal, bool isTopLevel)
static uint64	RunFromStore (Portal portal, ScanDirection direction, uint64 count, DestReceiver *dest)
static uint64	PortalRunSelect (Portal portal, bool forward, long count, DestReceiver *dest)
static void	PortalRunUtility (Portal portal, PlannedStmt *pstmt, bool isTopLevel, bool setHoldSnapshot, DestReceiver *dest, QueryCompletion *qc)
static void	PortalRunMulti (Portal portal, bool isTopLevel, bool setHoldSnapshot, DestReceiver *dest, DestReceiver *altdest, QueryCompletion *qc)
static uint64	DoPortalRunFetch (Portal portal, FetchDirection fdirection, long count, DestReceiver *dest)
static void	DoPortalRewind (Portal portal)
QueryDesc *	CreateQueryDesc (PlannedStmt *plannedstmt, const char *sourceText, Snapshot snapshot, Snapshot crosscheck_snapshot, DestReceiver *dest, ParamListInfo params, QueryEnvironment *queryEnv, int instrument_options)
void	FreeQueryDesc (QueryDesc *qdesc)
PortalStrategy	ChoosePortalStrategy (List *stmts)
List *	FetchPortalTargetList (Portal portal)
List *	FetchStatementTargetList (Node *stmt)
void	PortalStart (Portal portal, ParamListInfo params, int eflags, Snapshot snapshot)
void	PortalSetResultFormat (Portal portal, int nFormats, int16 *formats)
bool	PortalRun (Portal portal, long count, bool isTopLevel, bool run_once, DestReceiver *dest, DestReceiver *altdest, QueryCompletion *qc)
uint64	PortalRunFetch (Portal portal, FetchDirection fdirection, long count, DestReceiver *dest)
bool	PlannedStmtRequiresSnapshot (PlannedStmt *pstmt)
void	EnsurePortalSnapshotExists (void)

Variables
Portal	ActivePortal = NULL

Function Documentation

ChoosePortalStrategy()

PortalStrategy ChoosePortalStrategy

(

List *

stmts

)

Definition at line 209 of file pquery.c.

{
    int         nSetTag;
    ListCell   *lc;
 
    /*
     * PORTAL_ONE_SELECT and PORTAL_UTIL_SELECT need only consider the
     * single-statement case, since there are no rewrite rules that can add
     * auxiliary queries to a SELECT or a utility command. PORTAL_ONE_MOD_WITH
     * likewise allows only one top-level statement.
     */
    if (list_length(stmts) == 1)
    {
        Node       *stmt = (Node *) linitial(stmts);
 
        if (IsA(stmt, Query))
        {
            Query      *query = (Query *) stmt;
 
            if (query->canSetTag)
            {
                if (query->commandType == CMD_SELECT)
                {
                    if (query->hasModifyingCTE)
                        return PORTAL_ONE_MOD_WITH;
                    else
                        return PORTAL_ONE_SELECT;
                }
                if (query->commandType == CMD_UTILITY)
                {
                    if (UtilityReturnsTuples(query->utilityStmt))
                        return PORTAL_UTIL_SELECT;
                    /* it can't be ONE_RETURNING, so give up */
                    return PORTAL_MULTI_QUERY;
                }
            }
        }
        else if (IsA(stmt, PlannedStmt))
        {
            PlannedStmt *pstmt = (PlannedStmt *) stmt;
 
            if (pstmt->canSetTag)
            {
                if (pstmt->commandType == CMD_SELECT)
                {
                    if (pstmt->hasModifyingCTE)
                        return PORTAL_ONE_MOD_WITH;
                    else
                        return PORTAL_ONE_SELECT;
                }
                if (pstmt->commandType == CMD_UTILITY)
                {
                    if (UtilityReturnsTuples(pstmt->utilityStmt))
                        return PORTAL_UTIL_SELECT;
                    /* it can't be ONE_RETURNING, so give up */
                    return PORTAL_MULTI_QUERY;
                }
            }
        }
        else
            elog(ERROR, "unrecognized node type: %d", (int) nodeTag(stmt));
    }
 
    /*
     * PORTAL_ONE_RETURNING has to allow auxiliary queries added by rewrite.
     * Choose PORTAL_ONE_RETURNING if there is exactly one canSetTag query and
     * it has a RETURNING list.
     */
    nSetTag = 0;
    foreach(lc, stmts)
    {
        Node       *stmt = (Node *) lfirst(lc);
 
        if (IsA(stmt, Query))
        {
            Query      *query = (Query *) stmt;
 
            if (query->canSetTag)
            {
                if (++nSetTag > 1)
                    return PORTAL_MULTI_QUERY;  /* no need to look further */
                if (query->commandType == CMD_UTILITY ||
                    query->returningList == NIL)
                    return PORTAL_MULTI_QUERY;  /* no need to look further */
            }
        }
        else if (IsA(stmt, PlannedStmt))
        {
            PlannedStmt *pstmt = (PlannedStmt *) stmt;
 
            if (pstmt->canSetTag)
            {
                if (++nSetTag > 1)
                    return PORTAL_MULTI_QUERY;  /* no need to look further */
                if (pstmt->commandType == CMD_UTILITY ||
                    !pstmt->hasReturning)
                    return PORTAL_MULTI_QUERY;  /* no need to look further */
            }
        }
        else
            elog(ERROR, "unrecognized node type: %d", (int) nodeTag(stmt));
    }
    if (nSetTag == 1)
        return PORTAL_ONE_RETURNING;
 
    /* Else, it's the general case... */
    return PORTAL_MULTI_QUERY;
}

References PlannedStmt::canSetTag, CMD_SELECT, CMD_UTILITY, Query::commandType, PlannedStmt::commandType, elog, ERROR, PlannedStmt::hasModifyingCTE, PlannedStmt::hasReturning, IsA, lfirst, linitial, list_length(), NIL, nodeTag, PORTAL_MULTI_QUERY, PORTAL_ONE_MOD_WITH, PORTAL_ONE_RETURNING, PORTAL_ONE_SELECT, PORTAL_UTIL_SELECT, Query::returningList, stmt, UtilityReturnsTuples(), Query::utilityStmt, and PlannedStmt::utilityStmt.

Referenced by PlanCacheComputeResultDesc(), and PortalStart().

CreateQueryDesc()

QueryDesc* CreateQueryDesc	(	PlannedStmt *	plannedstmt,
		const char *	sourceText,
		Snapshot	snapshot,
		Snapshot	crosscheck_snapshot,
		DestReceiver *	dest,
		ParamListInfo	params,
		QueryEnvironment *	queryEnv,
		int	instrument_options
	)

Definition at line 67 of file pquery.c.

{
    QueryDesc  *qd = (QueryDesc *) palloc(sizeof(QueryDesc));
 
    qd->operation = plannedstmt->commandType;   /* operation */
    qd->plannedstmt = plannedstmt;  /* plan */
    qd->sourceText = sourceText;    /* query text */
    qd->snapshot = RegisterSnapshot(snapshot);  /* snapshot */
    /* RI check snapshot */
    qd->crosscheck_snapshot = RegisterSnapshot(crosscheck_snapshot);
    qd->dest = dest;            /* output dest */
    qd->params = params;        /* parameter values passed into query */
    qd->queryEnv = queryEnv;
    qd->instrument_options = instrument_options;    /* instrumentation wanted? */
 
    /* null these fields until set by ExecutorStart */
    qd->tupDesc = NULL;
    qd->estate = NULL;
    qd->planstate = NULL;
    qd->totaltime = NULL;
 
    /* not yet executed */
    qd->already_executed = false;
 
    return qd;
}

References QueryDesc::already_executed, PlannedStmt::commandType, QueryDesc::crosscheck_snapshot, generate_unaccent_rules::dest, QueryDesc::dest, QueryDesc::estate, QueryDesc::instrument_options, QueryDesc::operation, palloc(), QueryDesc::params, QueryDesc::plannedstmt, QueryDesc::planstate, QueryDesc::queryEnv, RegisterSnapshot(), QueryDesc::snapshot, QueryDesc::sourceText, QueryDesc::totaltime, and QueryDesc::tupDesc.

Referenced by _SPI_execute_plan(), BeginCopyTo(), ExecCreateTableAs(), ExecParallelGetQueryDesc(), execute_sql_string(), ExplainOnePlan(), PortalStart(), postquel_start(), ProcessQuery(), and refresh_matview_datafill().

DoPortalRewind()

static void DoPortalRewind ( Portal  portal )

static

Definition at line 1686 of file pquery.c.

{
    QueryDesc  *queryDesc;
 
    /*
     * No work is needed if we've not advanced nor attempted to advance the
     * cursor (and we don't want to throw a NO SCROLL error in this case).
     */
    if (portal->atStart && !portal->atEnd)
        return;
 
    /* Otherwise, cursor must allow scrolling */
    if (portal->cursorOptions & CURSOR_OPT_NO_SCROLL)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cursor can only scan forward"),
                 errhint("Declare it with SCROLL option to enable backward scan.")));
 
    /* Rewind holdStore, if we have one */
    if (portal->holdStore)
    {
        MemoryContext oldcontext;
 
        oldcontext = MemoryContextSwitchTo(portal->holdContext);
        tuplestore_rescan(portal->holdStore);
        MemoryContextSwitchTo(oldcontext);
    }
 
    /* Rewind executor, if active */
    queryDesc = portal->queryDesc;
    if (queryDesc)
    {
        PushActiveSnapshot(queryDesc->snapshot);
        ExecutorRewind(queryDesc);
        PopActiveSnapshot();
    }
 
    portal->atStart = true;
    portal->atEnd = false;
    portal->portalPos = 0;
}

References PortalData::atEnd, PortalData::atStart, CURSOR_OPT_NO_SCROLL, PortalData::cursorOptions, ereport, errcode(), errhint(), errmsg(), ERROR, ExecutorRewind(), PortalData::holdContext, PortalData::holdStore, MemoryContextSwitchTo(), PopActiveSnapshot(), PortalData::portalPos, PushActiveSnapshot(), PortalData::queryDesc, QueryDesc::snapshot, and tuplestore_rescan().

Referenced by DoPortalRunFetch().

DoPortalRunFetch()

static uint64 DoPortalRunFetch ( Portal  portal, FetchDirection  fdirection, long  count, DestReceiver *  dest  )

static

Definition at line 1492 of file pquery.c.

{
    bool        forward;
 
    Assert(portal->strategy == PORTAL_ONE_SELECT ||
           portal->strategy == PORTAL_ONE_RETURNING ||
           portal->strategy == PORTAL_ONE_MOD_WITH ||
           portal->strategy == PORTAL_UTIL_SELECT);
 
    /*
     * Note: we disallow backwards fetch (including re-fetch of current row)
     * for NO SCROLL cursors, but we interpret that very loosely: you can use
     * any of the FetchDirection options, so long as the end result is to move
     * forwards by at least one row.  Currently it's sufficient to check for
     * NO SCROLL in DoPortalRewind() and in the forward == false path in
     * PortalRunSelect(); but someday we might prefer to account for that
     * restriction explicitly here.
     */
    switch (fdirection)
    {
        case FETCH_FORWARD:
            if (count < 0)
            {
                fdirection = FETCH_BACKWARD;
                count = -count;
            }
            /* fall out of switch to share code with FETCH_BACKWARD */
            break;
        case FETCH_BACKWARD:
            if (count < 0)
            {
                fdirection = FETCH_FORWARD;
                count = -count;
            }
            /* fall out of switch to share code with FETCH_FORWARD */
            break;
        case FETCH_ABSOLUTE:
            if (count > 0)
            {
                /*
                 * Definition: Rewind to start, advance count-1 rows, return
                 * next row (if any).
                 *
                 * In practice, if the goal is less than halfway back to the
                 * start, it's better to scan from where we are.
                 *
                 * Also, if current portalPos is outside the range of "long",
                 * do it the hard way to avoid possible overflow of the count
                 * argument to PortalRunSelect.  We must exclude exactly
                 * LONG_MAX, as well, lest the count look like FETCH_ALL.
                 *
                 * In any case, we arrange to fetch the target row going
                 * forwards.
                 */
                if ((uint64) (count - 1) <= portal->portalPos / 2 ||
                    portal->portalPos >= (uint64) LONG_MAX)
                {
                    DoPortalRewind(portal);
                    if (count > 1)
                        PortalRunSelect(portal, true, count - 1,
                                        None_Receiver);
                }
                else
                {
                    long        pos = (long) portal->portalPos;
 
                    if (portal->atEnd)
                        pos++;  /* need one extra fetch if off end */
                    if (count <= pos)
                        PortalRunSelect(portal, false, pos - count + 1,
                                        None_Receiver);
                    else if (count > pos + 1)
                        PortalRunSelect(portal, true, count - pos - 1,
                                        None_Receiver);
                }
                return PortalRunSelect(portal, true, 1L, dest);
            }
            else if (count < 0)
            {
                /*
                 * Definition: Advance to end, back up abs(count)-1 rows,
                 * return prior row (if any).  We could optimize this if we
                 * knew in advance where the end was, but typically we won't.
                 * (Is it worth considering case where count > half of size of
                 * query?  We could rewind once we know the size ...)
                 */
                PortalRunSelect(portal, true, FETCH_ALL, None_Receiver);
                if (count < -1)
                    PortalRunSelect(portal, false, -count - 1, None_Receiver);
                return PortalRunSelect(portal, false, 1L, dest);
            }
            else
            {
                /* count == 0 */
                /* Rewind to start, return zero rows */
                DoPortalRewind(portal);
                return PortalRunSelect(portal, true, 0L, dest);
            }
            break;
        case FETCH_RELATIVE:
            if (count > 0)
            {
                /*
                 * Definition: advance count-1 rows, return next row (if any).
                 */
                if (count > 1)
                    PortalRunSelect(portal, true, count - 1, None_Receiver);
                return PortalRunSelect(portal, true, 1L, dest);
            }
            else if (count < 0)
            {
                /*
                 * Definition: back up abs(count)-1 rows, return prior row (if
                 * any).
                 */
                if (count < -1)
                    PortalRunSelect(portal, false, -count - 1, None_Receiver);
                return PortalRunSelect(portal, false, 1L, dest);
            }
            else
            {
                /* count == 0 */
                /* Same as FETCH FORWARD 0, so fall out of switch */
                fdirection = FETCH_FORWARD;
            }
            break;
        default:
            elog(ERROR, "bogus direction");
            break;
    }
 
    /*
     * Get here with fdirection == FETCH_FORWARD or FETCH_BACKWARD, and count
     * >= 0.
     */
    forward = (fdirection == FETCH_FORWARD);
 
    /*
     * Zero count means to re-fetch the current row, if any (per SQL)
     */
    if (count == 0)
    {
        bool        on_row;
 
        /* Are we sitting on a row? */
        on_row = (!portal->atStart && !portal->atEnd);
 
        if (dest->mydest == DestNone)
        {
            /* MOVE 0 returns 0/1 based on if FETCH 0 would return a row */
            return on_row ? 1 : 0;
        }
        else
        {
            /*
             * If we are sitting on a row, back up one so we can re-fetch it.
             * If we are not sitting on a row, we still have to start up and
             * shut down the executor so that the destination is initialized
             * and shut down correctly; so keep going.  To PortalRunSelect,
             * count == 0 means we will retrieve no row.
             */
            if (on_row)
            {
                PortalRunSelect(portal, false, 1L, None_Receiver);
                /* Set up to fetch one row forward */
                count = 1;
                forward = true;
            }
        }
    }
 
    /*
     * Optimize MOVE BACKWARD ALL into a Rewind.
     */
    if (!forward && count == FETCH_ALL && dest->mydest == DestNone)
    {
        uint64      result = portal->portalPos;
 
        if (result > 0 && !portal->atEnd)
            result--;
        DoPortalRewind(portal);
        return result;
    }
 
    return PortalRunSelect(portal, forward, count, dest);
}

References Assert, PortalData::atEnd, PortalData::atStart, generate_unaccent_rules::dest, DestNone, DoPortalRewind(), elog, ERROR, FETCH_ABSOLUTE, FETCH_ALL, FETCH_BACKWARD, FETCH_FORWARD, FETCH_RELATIVE, if(), None_Receiver, PORTAL_ONE_MOD_WITH, PORTAL_ONE_RETURNING, PORTAL_ONE_SELECT, PORTAL_UTIL_SELECT, PortalData::portalPos, PortalRunSelect(), and PortalData::strategy.

Referenced by PortalRunFetch().

EnsurePortalSnapshotExists()

void EnsurePortalSnapshotExists

(

void

)

Definition at line 1780 of file pquery.c.

{
    Portal      portal;
 
    /*
     * Nothing to do if a snapshot is set.  (We take it on faith that the
     * outermost active snapshot belongs to some Portal; or if there is no
     * Portal, it's somebody else's responsibility to manage things.)
     */
    if (ActiveSnapshotSet())
        return;
 
    /* Otherwise, we'd better have an active Portal */
    portal = ActivePortal;
    if (unlikely(portal == NULL))
        elog(ERROR, "cannot execute SQL without an outer snapshot or portal");
    Assert(portal->portalSnapshot == NULL);
 
    /*
     * Create a new snapshot, make it active, and remember it in portal.
     * Because the portal now references the snapshot, we must tell snapmgr.c
     * that the snapshot belongs to the portal's transaction level, else we
     * risk portalSnapshot becoming a dangling pointer.
     */
    PushActiveSnapshotWithLevel(GetTransactionSnapshot(), portal->createLevel);
    /* PushActiveSnapshotWithLevel might have copied the snapshot */
    portal->portalSnapshot = GetActiveSnapshot();
}

References ActivePortal, ActiveSnapshotSet(), Assert, PortalData::createLevel, elog, ERROR, GetActiveSnapshot(), GetTransactionSnapshot(), PortalData::portalSnapshot, PushActiveSnapshotWithLevel(), and unlikely.

Referenced by _SPI_execute_plan(), exec_eval_simple_expr(), and ExecuteCallStmt().

FetchPortalTargetList()

List* FetchPortalTargetList

(

Portal

portal

)

Definition at line 326 of file pquery.c.

{
    /* no point in looking if we determined it doesn't return tuples */
    if (portal->strategy == PORTAL_MULTI_QUERY)
        return NIL;
    /* get the primary statement and find out what it returns */
    return FetchStatementTargetList((Node *) PortalGetPrimaryStmt(portal));
}

References FetchStatementTargetList(), NIL, PORTAL_MULTI_QUERY, PortalGetPrimaryStmt(), and PortalData::strategy.

Referenced by exec_describe_portal_message(), FetchStatementTargetList(), and printtup_startup().

FetchStatementTargetList()

List* FetchStatementTargetList

(

Node *

stmt

)

Definition at line 348 of file pquery.c.

{
    if (stmt == NULL)
        return NIL;
    if (IsA(stmt, Query))
    {
        Query      *query = (Query *) stmt;
 
        if (query->commandType == CMD_UTILITY)
        {
            /* transfer attention to utility statement */
            stmt = query->utilityStmt;
        }
        else
        {
            if (query->commandType == CMD_SELECT)
                return query->targetList;
            if (query->returningList)
                return query->returningList;
            return NIL;
        }
    }
    if (IsA(stmt, PlannedStmt))
    {
        PlannedStmt *pstmt = (PlannedStmt *) stmt;
 
        if (pstmt->commandType == CMD_UTILITY)
        {
            /* transfer attention to utility statement */
            stmt = pstmt->utilityStmt;
        }
        else
        {
            if (pstmt->commandType == CMD_SELECT)
                return pstmt->planTree->targetlist;
            if (pstmt->hasReturning)
                return pstmt->planTree->targetlist;
            return NIL;
        }
    }
    if (IsA(stmt, FetchStmt))
    {
        FetchStmt  *fstmt = (FetchStmt *) stmt;
        Portal      subportal;
 
        Assert(!fstmt->ismove);
        subportal = GetPortalByName(fstmt->portalname);
        Assert(PortalIsValid(subportal));
        return FetchPortalTargetList(subportal);
    }
    if (IsA(stmt, ExecuteStmt))
    {
        ExecuteStmt *estmt = (ExecuteStmt *) stmt;
        PreparedStatement *entry;
 
        entry = FetchPreparedStatement(estmt->name, true);
        return FetchPreparedStatementTargetList(entry);
    }
    return NIL;
}

References Assert, CMD_SELECT, CMD_UTILITY, Query::commandType, PlannedStmt::commandType, FetchPortalTargetList(), FetchPreparedStatement(), FetchPreparedStatementTargetList(), GetPortalByName(), PlannedStmt::hasReturning, IsA, FetchStmt::ismove, ExecuteStmt::name, NIL, PlannedStmt::planTree, PortalIsValid, FetchStmt::portalname, Query::returningList, stmt, Query::targetList, Plan::targetlist, Query::utilityStmt, and PlannedStmt::utilityStmt.

Referenced by CachedPlanGetTargetList(), and FetchPortalTargetList().

FillPortalStore()

static void FillPortalStore ( Portal  portal, bool  isTopLevel  )

static

Definition at line 1000 of file pquery.c.

{
    DestReceiver *treceiver;
    QueryCompletion qc;
 
    InitializeQueryCompletion(&qc);
    PortalCreateHoldStore(portal);
    treceiver = CreateDestReceiver(DestTuplestore);
    SetTuplestoreDestReceiverParams(treceiver,
                                    portal->holdStore,
                                    portal->holdContext,
                                    false,
                                    NULL,
                                    NULL);
 
    switch (portal->strategy)
    {
        case PORTAL_ONE_RETURNING:
        case PORTAL_ONE_MOD_WITH:
 
            /*
             * Run the portal to completion just as for the default
             * PORTAL_MULTI_QUERY case, but send the primary query's output to
             * the tuplestore.  Auxiliary query outputs are discarded. Set the
             * portal's holdSnapshot to the snapshot used (or a copy of it).
             */
            PortalRunMulti(portal, isTopLevel, true,
                           treceiver, None_Receiver, &qc);
            break;
 
        case PORTAL_UTIL_SELECT:
            PortalRunUtility(portal, linitial_node(PlannedStmt, portal->stmts),
                             isTopLevel, true, treceiver, &qc);
            break;
 
        default:
            elog(ERROR, "unsupported portal strategy: %d",
                 (int) portal->strategy);
            break;
    }
 
    /* Override portal completion data with actual command results */
    if (qc.commandTag != CMDTAG_UNKNOWN)
        CopyQueryCompletion(&portal->qc, &qc);
 
    treceiver->rDestroy(treceiver);
}

References QueryCompletion::commandTag, CopyQueryCompletion(), CreateDestReceiver(), DestTuplestore, elog, ERROR, PortalData::holdContext, PortalData::holdStore, InitializeQueryCompletion(), linitial_node, None_Receiver, PORTAL_ONE_MOD_WITH, PORTAL_ONE_RETURNING, PORTAL_UTIL_SELECT, PortalCreateHoldStore(), PortalRunMulti(), PortalRunUtility(), PortalData::qc, _DestReceiver::rDestroy, SetTuplestoreDestReceiverParams(), PortalData::stmts, and PortalData::strategy.

Referenced by PortalRun(), and PortalRunFetch().

FreeQueryDesc()

void FreeQueryDesc

(

QueryDesc *

qdesc

)

Definition at line 105 of file pquery.c.

{
    /* Can't be a live query */
    Assert(qdesc->estate == NULL);
 
    /* forget our snapshots */
    UnregisterSnapshot(qdesc->snapshot);
    UnregisterSnapshot(qdesc->crosscheck_snapshot);
 
    /* Only the QueryDesc itself need be freed */
    pfree(qdesc);
}

References Assert, QueryDesc::crosscheck_snapshot, QueryDesc::estate, pfree(), QueryDesc::snapshot, and UnregisterSnapshot().

Referenced by _SPI_execute_plan(), EndCopyTo(), ExecCreateTableAs(), execute_sql_string(), ExplainOnePlan(), ParallelQueryMain(), PersistHoldablePortal(), PortalCleanup(), postquel_end(), ProcessQuery(), and refresh_matview_datafill().

PlannedStmtRequiresSnapshot()

bool PlannedStmtRequiresSnapshot

(

PlannedStmt *

pstmt

)

Definition at line 1732 of file pquery.c.

{
    Node       *utilityStmt = pstmt->utilityStmt;
 
    /* If it's not a utility statement, it definitely needs a snapshot */
    if (utilityStmt == NULL)
        return true;
 
    /*
     * Most utility statements need a snapshot, and the default presumption
     * about new ones should be that they do too.  Hence, enumerate those that
     * do not need one.
     *
     * Transaction control, LOCK, and SET must *not* set a snapshot, since
     * they need to be executable at the start of a transaction-snapshot-mode
     * transaction without freezing a snapshot.  By extension we allow SHOW
     * not to set a snapshot.  The other stmts listed are just efficiency
     * hacks.  Beware of listing anything that can modify the database --- if,
     * say, it has to update an index with expressions that invoke
     * user-defined functions, then it had better have a snapshot.
     */
    if (IsA(utilityStmt, TransactionStmt) ||
        IsA(utilityStmt, LockStmt) ||
        IsA(utilityStmt, VariableSetStmt) ||
        IsA(utilityStmt, VariableShowStmt) ||
        IsA(utilityStmt, ConstraintsSetStmt) ||
    /* efficiency hacks from here down */
        IsA(utilityStmt, FetchStmt) ||
        IsA(utilityStmt, ListenStmt) ||
        IsA(utilityStmt, NotifyStmt) ||
        IsA(utilityStmt, UnlistenStmt) ||
        IsA(utilityStmt, CheckPointStmt))
        return false;
 
    return true;
}

References IsA, and PlannedStmt::utilityStmt.

Referenced by _SPI_execute_plan(), and PortalRunUtility().

PortalRun()

bool PortalRun	(	Portal	portal,
		long	count,
		bool	isTopLevel,
		bool	run_once,
		DestReceiver *	dest,
		DestReceiver *	altdest,
		QueryCompletion *	qc
	)

Definition at line 684 of file pquery.c.

{
    bool        result;
    uint64      nprocessed;
    ResourceOwner saveTopTransactionResourceOwner;
    MemoryContext saveTopTransactionContext;
    Portal      saveActivePortal;
    ResourceOwner saveResourceOwner;
    MemoryContext savePortalContext;
    MemoryContext saveMemoryContext;
 
    Assert(PortalIsValid(portal));
 
    TRACE_POSTGRESQL_QUERY_EXECUTE_START();
 
    /* Initialize empty completion data */
    if (qc)
        InitializeQueryCompletion(qc);
 
    if (log_executor_stats && portal->strategy != PORTAL_MULTI_QUERY)
    {
        elog(DEBUG3, "PortalRun");
        /* PORTAL_MULTI_QUERY logs its own stats per query */
        ResetUsage();
    }
 
    /*
     * Check for improper portal use, and mark portal active.
     */
    MarkPortalActive(portal);
 
    /* Set run_once flag.  Shouldn't be clear if previously set. */
    Assert(!portal->run_once || run_once);
    portal->run_once = run_once;
 
    /*
     * Set up global portal context pointers.
     *
     * We have to play a special game here to support utility commands like
     * VACUUM and CLUSTER, which internally start and commit transactions.
     * When we are called to execute such a command, CurrentResourceOwner will
     * be pointing to the TopTransactionResourceOwner --- which will be
     * destroyed and replaced in the course of the internal commit and
     * restart.  So we need to be prepared to restore it as pointing to the
     * exit-time TopTransactionResourceOwner.  (Ain't that ugly?  This idea of
     * internally starting whole new transactions is not good.)
     * CurrentMemoryContext has a similar problem, but the other pointers we
     * save here will be NULL or pointing to longer-lived objects.
     */
    saveTopTransactionResourceOwner = TopTransactionResourceOwner;
    saveTopTransactionContext = TopTransactionContext;
    saveActivePortal = ActivePortal;
    saveResourceOwner = CurrentResourceOwner;
    savePortalContext = PortalContext;
    saveMemoryContext = CurrentMemoryContext;
    PG_TRY();
    {
        ActivePortal = portal;
        if (portal->resowner)
            CurrentResourceOwner = portal->resowner;
        PortalContext = portal->portalContext;
 
        MemoryContextSwitchTo(PortalContext);
 
        switch (portal->strategy)
        {
            case PORTAL_ONE_SELECT:
            case PORTAL_ONE_RETURNING:
            case PORTAL_ONE_MOD_WITH:
            case PORTAL_UTIL_SELECT:
 
                /*
                 * If we have not yet run the command, do so, storing its
                 * results in the portal's tuplestore.  But we don't do that
                 * for the PORTAL_ONE_SELECT case.
                 */
                if (portal->strategy != PORTAL_ONE_SELECT && !portal->holdStore)
                    FillPortalStore(portal, isTopLevel);
 
                /*
                 * Now fetch desired portion of results.
                 */
                nprocessed = PortalRunSelect(portal, true, count, dest);
 
                /*
                 * If the portal result contains a command tag and the caller
                 * gave us a pointer to store it, copy it and update the
                 * rowcount.
                 */
                if (qc && portal->qc.commandTag != CMDTAG_UNKNOWN)
                {
                    CopyQueryCompletion(qc, &portal->qc);
                    qc->nprocessed = nprocessed;
                }
 
                /* Mark portal not active */
                portal->status = PORTAL_READY;
 
                /*
                 * Since it's a forward fetch, say DONE iff atEnd is now true.
                 */
                result = portal->atEnd;
                break;
 
            case PORTAL_MULTI_QUERY:
                PortalRunMulti(portal, isTopLevel, false,
                               dest, altdest, qc);
 
                /* Prevent portal's commands from being re-executed */
                MarkPortalDone(portal);
 
                /* Always complete at end of RunMulti */
                result = true;
                break;
 
            default:
                elog(ERROR, "unrecognized portal strategy: %d",
                     (int) portal->strategy);
                result = false; /* keep compiler quiet */
                break;
        }
    }
    PG_CATCH();
    {
        /* Uncaught error while executing portal: mark it dead */
        MarkPortalFailed(portal);
 
        /* Restore global vars and propagate error */
        if (saveMemoryContext == saveTopTransactionContext)
            MemoryContextSwitchTo(TopTransactionContext);
        else
            MemoryContextSwitchTo(saveMemoryContext);
        ActivePortal = saveActivePortal;
        if (saveResourceOwner == saveTopTransactionResourceOwner)
            CurrentResourceOwner = TopTransactionResourceOwner;
        else
            CurrentResourceOwner = saveResourceOwner;
        PortalContext = savePortalContext;
 
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    if (saveMemoryContext == saveTopTransactionContext)
        MemoryContextSwitchTo(TopTransactionContext);
    else
        MemoryContextSwitchTo(saveMemoryContext);
    ActivePortal = saveActivePortal;
    if (saveResourceOwner == saveTopTransactionResourceOwner)
        CurrentResourceOwner = TopTransactionResourceOwner;
    else
        CurrentResourceOwner = saveResourceOwner;
    PortalContext = savePortalContext;
 
    if (log_executor_stats && portal->strategy != PORTAL_MULTI_QUERY)
        ShowUsage("EXECUTOR STATISTICS");
 
    TRACE_POSTGRESQL_QUERY_EXECUTE_DONE();
 
    return result;
}

References ActivePortal, Assert, PortalData::atEnd, QueryCompletion::commandTag, CopyQueryCompletion(), CurrentMemoryContext, CurrentResourceOwner, DEBUG3, generate_unaccent_rules::dest, elog, ERROR, FillPortalStore(), PortalData::holdStore, InitializeQueryCompletion(), log_executor_stats, MarkPortalActive(), MarkPortalDone(), MarkPortalFailed(), MemoryContextSwitchTo(), QueryCompletion::nprocessed, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PORTAL_MULTI_QUERY, PORTAL_ONE_MOD_WITH, PORTAL_ONE_RETURNING, PORTAL_ONE_SELECT, PORTAL_READY, PORTAL_UTIL_SELECT, PortalContext, PortalData::portalContext, PortalIsValid, PortalRunMulti(), PortalRunSelect(), PortalData::qc, ResetUsage(), PortalData::resowner, PortalData::run_once, ShowUsage(), PortalData::status, PortalData::strategy, TopTransactionContext, and TopTransactionResourceOwner.

Referenced by exec_execute_message(), exec_simple_query(), and ExecuteQuery().

PortalRunFetch()

uint64 PortalRunFetch	(	Portal	portal,
		FetchDirection	fdirection,
		long	count,
		DestReceiver *	dest
	)

Definition at line 1391 of file pquery.c.

{
    uint64      result;
    Portal      saveActivePortal;
    ResourceOwner saveResourceOwner;
    MemoryContext savePortalContext;
    MemoryContext oldContext;
 
    Assert(PortalIsValid(portal));
 
    /*
     * Check for improper portal use, and mark portal active.
     */
    MarkPortalActive(portal);
 
    /* If supporting FETCH, portal can't be run-once. */
    Assert(!portal->run_once);
 
    /*
     * Set up global portal context pointers.
     */
    saveActivePortal = ActivePortal;
    saveResourceOwner = CurrentResourceOwner;
    savePortalContext = PortalContext;
    PG_TRY();
    {
        ActivePortal = portal;
        if (portal->resowner)
            CurrentResourceOwner = portal->resowner;
        PortalContext = portal->portalContext;
 
        oldContext = MemoryContextSwitchTo(PortalContext);
 
        switch (portal->strategy)
        {
            case PORTAL_ONE_SELECT:
                result = DoPortalRunFetch(portal, fdirection, count, dest);
                break;
 
            case PORTAL_ONE_RETURNING:
            case PORTAL_ONE_MOD_WITH:
            case PORTAL_UTIL_SELECT:
 
                /*
                 * If we have not yet run the command, do so, storing its
                 * results in the portal's tuplestore.
                 */
                if (!portal->holdStore)
                    FillPortalStore(portal, false /* isTopLevel */ );
 
                /*
                 * Now fetch desired portion of results.
                 */
                result = DoPortalRunFetch(portal, fdirection, count, dest);
                break;
 
            default:
                elog(ERROR, "unsupported portal strategy");
                result = 0;     /* keep compiler quiet */
                break;
        }
    }
    PG_CATCH();
    {
        /* Uncaught error while executing portal: mark it dead */
        MarkPortalFailed(portal);
 
        /* Restore global vars and propagate error */
        ActivePortal = saveActivePortal;
        CurrentResourceOwner = saveResourceOwner;
        PortalContext = savePortalContext;
 
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    MemoryContextSwitchTo(oldContext);
 
    /* Mark portal not active */
    portal->status = PORTAL_READY;
 
    ActivePortal = saveActivePortal;
    CurrentResourceOwner = saveResourceOwner;
    PortalContext = savePortalContext;
 
    return result;
}

References ActivePortal, Assert, CurrentResourceOwner, generate_unaccent_rules::dest, DoPortalRunFetch(), elog, ERROR, FillPortalStore(), PortalData::holdStore, MarkPortalActive(), MarkPortalFailed(), MemoryContextSwitchTo(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PORTAL_ONE_MOD_WITH, PORTAL_ONE_RETURNING, PORTAL_ONE_SELECT, PORTAL_READY, PORTAL_UTIL_SELECT, PortalContext, PortalData::portalContext, PortalIsValid, PortalData::resowner, PortalData::run_once, PortalData::status, and PortalData::strategy.

Referenced by _SPI_cursor_operation(), and PerformPortalFetch().

PortalRunMulti()

static void PortalRunMulti ( Portal  portal, bool  isTopLevel, bool  setHoldSnapshot, DestReceiver *  dest, DestReceiver *  altdest, QueryCompletion *  qc  )

static

Definition at line 1190 of file pquery.c.

{
    bool        active_snapshot_set = false;
    ListCell   *stmtlist_item;
 
    /*
     * If the destination is DestRemoteExecute, change to DestNone.  The
     * reason is that the client won't be expecting any tuples, and indeed has
     * no way to know what they are, since there is no provision for Describe
     * to send a RowDescription message when this portal execution strategy is
     * in effect.  This presently will only affect SELECT commands added to
     * non-SELECT queries by rewrite rules: such commands will be executed,
     * but the results will be discarded unless you use "simple Query"
     * protocol.
     */
    if (dest->mydest == DestRemoteExecute)
        dest = None_Receiver;
    if (altdest->mydest == DestRemoteExecute)
        altdest = None_Receiver;
 
    /*
     * Loop to handle the individual queries generated from a single parsetree
     * by analysis and rewrite.
     */
    foreach(stmtlist_item, portal->stmts)
    {
        PlannedStmt *pstmt = lfirst_node(PlannedStmt, stmtlist_item);
 
        /*
         * If we got a cancel signal in prior command, quit
         */
        CHECK_FOR_INTERRUPTS();
 
        if (pstmt->utilityStmt == NULL)
        {
            /*
             * process a plannable query.
             */
            TRACE_POSTGRESQL_QUERY_EXECUTE_START();
 
            if (log_executor_stats)
                ResetUsage();
 
            /*
             * Must always have a snapshot for plannable queries.  First time
             * through, take a new snapshot; for subsequent queries in the
             * same portal, just update the snapshot's copy of the command
             * counter.
             */
            if (!active_snapshot_set)
            {
                Snapshot    snapshot = GetTransactionSnapshot();
 
                /* If told to, register the snapshot and save in portal */
                if (setHoldSnapshot)
                {
                    snapshot = RegisterSnapshot(snapshot);
                    portal->holdSnapshot = snapshot;
                }
 
                /*
                 * We can't have the holdSnapshot also be the active one,
                 * because UpdateActiveSnapshotCommandId would complain.  So
                 * force an extra snapshot copy.  Plain PushActiveSnapshot
                 * would have copied the transaction snapshot anyway, so this
                 * only adds a copy step when setHoldSnapshot is true.  (It's
                 * okay for the command ID of the active snapshot to diverge
                 * from what holdSnapshot has.)
                 */
                PushCopiedSnapshot(snapshot);
 
                /*
                 * As for PORTAL_ONE_SELECT portals, it does not seem
                 * necessary to maintain portal->portalSnapshot here.
                 */
 
                active_snapshot_set = true;
            }
            else
                UpdateActiveSnapshotCommandId();
 
            if (pstmt->canSetTag)
            {
                /* statement can set tag string */
                ProcessQuery(pstmt,
                             portal->sourceText,
                             portal->portalParams,
                             portal->queryEnv,
                             dest, qc);
            }
            else
            {
                /* stmt added by rewrite cannot set tag */
                ProcessQuery(pstmt,
                             portal->sourceText,
                             portal->portalParams,
                             portal->queryEnv,
                             altdest, NULL);
            }
 
            if (log_executor_stats)
                ShowUsage("EXECUTOR STATISTICS");
 
            TRACE_POSTGRESQL_QUERY_EXECUTE_DONE();
        }
        else
        {
            /*
             * process utility functions (create, destroy, etc..)
             *
             * We must not set a snapshot here for utility commands (if one is
             * needed, PortalRunUtility will do it).  If a utility command is
             * alone in a portal then everything's fine.  The only case where
             * a utility command can be part of a longer list is that rules
             * are allowed to include NotifyStmt.  NotifyStmt doesn't care
             * whether it has a snapshot or not, so we just leave the current
             * snapshot alone if we have one.
             */
            if (pstmt->canSetTag)
            {
                Assert(!active_snapshot_set);
                /* statement can set tag string */
                PortalRunUtility(portal, pstmt, isTopLevel, false,
                                 dest, qc);
            }
            else
            {
                Assert(IsA(pstmt->utilityStmt, NotifyStmt));
                /* stmt added by rewrite cannot set tag */
                PortalRunUtility(portal, pstmt, isTopLevel, false,
                                 altdest, NULL);
            }
        }
 
        /*
         * Clear subsidiary contexts to recover temporary memory.
         */
        Assert(portal->portalContext == CurrentMemoryContext);
 
        MemoryContextDeleteChildren(portal->portalContext);
 
        /*
         * Avoid crashing if portal->stmts has been reset.  This can only
         * occur if a CALL or DO utility statement executed an internal
         * COMMIT/ROLLBACK (cf PortalReleaseCachedPlan).  The CALL or DO must
         * have been the only statement in the portal, so there's nothing left
         * for us to do; but we don't want to dereference a now-dangling list
         * pointer.
         */
        if (portal->stmts == NIL)
            break;
 
        /*
         * Increment command counter between queries, but not after the last
         * one.
         */
        if (lnext(portal->stmts, stmtlist_item) != NULL)
            CommandCounterIncrement();
    }
 
    /* Pop the snapshot if we pushed one. */
    if (active_snapshot_set)
        PopActiveSnapshot();
 
    /*
     * If a query completion data was supplied, use it.  Otherwise use the
     * portal's query completion data.
     *
     * Exception: Clients expect INSERT/UPDATE/DELETE tags to have counts, so
     * fake them with zeros.  This can happen with DO INSTEAD rules if there
     * is no replacement query of the same type as the original.  We print "0
     * 0" here because technically there is no query of the matching tag type,
     * and printing a non-zero count for a different query type seems wrong,
     * e.g.  an INSERT that does an UPDATE instead should not print "0 1" if
     * one row was updated.  See QueryRewrite(), step 3, for details.
     */
    if (qc && qc->commandTag == CMDTAG_UNKNOWN)
    {
        if (portal->qc.commandTag != CMDTAG_UNKNOWN)
            CopyQueryCompletion(qc, &portal->qc);
        /* If the caller supplied a qc, we should have set it by now. */
        Assert(qc->commandTag != CMDTAG_UNKNOWN);
    }
}

References Assert, PlannedStmt::canSetTag, CHECK_FOR_INTERRUPTS, CommandCounterIncrement(), QueryCompletion::commandTag, CopyQueryCompletion(), CurrentMemoryContext, generate_unaccent_rules::dest, DestRemoteExecute, GetTransactionSnapshot(), PortalData::holdSnapshot, IsA, lfirst_node, lnext(), log_executor_stats, MemoryContextDeleteChildren(), _DestReceiver::mydest, NIL, None_Receiver, PopActiveSnapshot(), PortalData::portalContext, PortalData::portalParams, PortalRunUtility(), ProcessQuery(), PushCopiedSnapshot(), PortalData::qc, PortalData::queryEnv, RegisterSnapshot(), ResetUsage(), ShowUsage(), PortalData::sourceText, PortalData::stmts, UpdateActiveSnapshotCommandId(), and PlannedStmt::utilityStmt.

Referenced by FillPortalStore(), and PortalRun().

PortalRunSelect()

static uint64 PortalRunSelect ( Portal  portal, bool  forward, long  count, DestReceiver *  dest  )

static

Definition at line 867 of file pquery.c.

{
    QueryDesc  *queryDesc;
    ScanDirection direction;
    uint64      nprocessed;
 
    /*
     * NB: queryDesc will be NULL if we are fetching from a held cursor or a
     * completed utility query; can't use it in that path.
     */
    queryDesc = portal->queryDesc;
 
    /* Caller messed up if we have neither a ready query nor held data. */
    Assert(queryDesc || portal->holdStore);
 
    /*
     * Force the queryDesc destination to the right thing.  This supports
     * MOVE, for example, which will pass in dest = DestNone.  This is okay to
     * change as long as we do it on every fetch.  (The Executor must not
     * assume that dest never changes.)
     */
    if (queryDesc)
        queryDesc->dest = dest;
 
    /*
     * Determine which direction to go in, and check to see if we're already
     * at the end of the available tuples in that direction.  If so, set the
     * direction to NoMovement to avoid trying to fetch any tuples.  (This
     * check exists because not all plan node types are robust about being
     * called again if they've already returned NULL once.)  Then call the
     * executor (we must not skip this, because the destination needs to see a
     * setup and shutdown even if no tuples are available).  Finally, update
     * the portal position state depending on the number of tuples that were
     * retrieved.
     */
    if (forward)
    {
        if (portal->atEnd || count <= 0)
        {
            direction = NoMovementScanDirection;
            count = 0;          /* don't pass negative count to executor */
        }
        else
            direction = ForwardScanDirection;
 
        /* In the executor, zero count processes all rows */
        if (count == FETCH_ALL)
            count = 0;
 
        if (portal->holdStore)
            nprocessed = RunFromStore(portal, direction, (uint64) count, dest);
        else
        {
            PushActiveSnapshot(queryDesc->snapshot);
            ExecutorRun(queryDesc, direction, (uint64) count,
                        portal->run_once);
            nprocessed = queryDesc->estate->es_processed;
            PopActiveSnapshot();
        }
 
        if (!ScanDirectionIsNoMovement(direction))
        {
            if (nprocessed > 0)
                portal->atStart = false;    /* OK to go backward now */
            if (count == 0 || nprocessed < (uint64) count)
                portal->atEnd = true;   /* we retrieved 'em all */
            portal->portalPos += nprocessed;
        }
    }
    else
    {
        if (portal->cursorOptions & CURSOR_OPT_NO_SCROLL)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("cursor can only scan forward"),
                     errhint("Declare it with SCROLL option to enable backward scan.")));
 
        if (portal->atStart || count <= 0)
        {
            direction = NoMovementScanDirection;
            count = 0;          /* don't pass negative count to executor */
        }
        else
            direction = BackwardScanDirection;
 
        /* In the executor, zero count processes all rows */
        if (count == FETCH_ALL)
            count = 0;
 
        if (portal->holdStore)
            nprocessed = RunFromStore(portal, direction, (uint64) count, dest);
        else
        {
            PushActiveSnapshot(queryDesc->snapshot);
            ExecutorRun(queryDesc, direction, (uint64) count,
                        portal->run_once);
            nprocessed = queryDesc->estate->es_processed;
            PopActiveSnapshot();
        }
 
        if (!ScanDirectionIsNoMovement(direction))
        {
            if (nprocessed > 0 && portal->atEnd)
            {
                portal->atEnd = false;  /* OK to go forward now */
                portal->portalPos++;    /* adjust for endpoint case */
            }
            if (count == 0 || nprocessed < (uint64) count)
            {
                portal->atStart = true; /* we retrieved 'em all */
                portal->portalPos = 0;
            }
            else
            {
                portal->portalPos -= nprocessed;
            }
        }
    }
 
    return nprocessed;
}

References Assert, PortalData::atEnd, PortalData::atStart, BackwardScanDirection, CURSOR_OPT_NO_SCROLL, PortalData::cursorOptions, generate_unaccent_rules::dest, QueryDesc::dest, ereport, errcode(), errhint(), errmsg(), ERROR, EState::es_processed, QueryDesc::estate, ExecutorRun(), FETCH_ALL, ForwardScanDirection, PortalData::holdStore, NoMovementScanDirection, PopActiveSnapshot(), PortalData::portalPos, PushActiveSnapshot(), PortalData::queryDesc, PortalData::run_once, RunFromStore(), ScanDirectionIsNoMovement, and QueryDesc::snapshot.

Referenced by DoPortalRunFetch(), and PortalRun().

PortalRunUtility()

static void PortalRunUtility ( Portal  portal, PlannedStmt *  pstmt, bool  isTopLevel, bool  setHoldSnapshot, DestReceiver *  dest, QueryCompletion *  qc  )

static

Definition at line 1127 of file pquery.c.

{
    /*
     * Set snapshot if utility stmt needs one.
     */
    if (PlannedStmtRequiresSnapshot(pstmt))
    {
        Snapshot    snapshot = GetTransactionSnapshot();
 
        /* If told to, register the snapshot we're using and save in portal */
        if (setHoldSnapshot)
        {
            snapshot = RegisterSnapshot(snapshot);
            portal->holdSnapshot = snapshot;
        }
 
        /*
         * In any case, make the snapshot active and remember it in portal.
         * Because the portal now references the snapshot, we must tell
         * snapmgr.c that the snapshot belongs to the portal's transaction
         * level, else we risk portalSnapshot becoming a dangling pointer.
         */
        PushActiveSnapshotWithLevel(snapshot, portal->createLevel);
        /* PushActiveSnapshotWithLevel might have copied the snapshot */
        portal->portalSnapshot = GetActiveSnapshot();
    }
    else
        portal->portalSnapshot = NULL;
 
    ProcessUtility(pstmt,
                   portal->sourceText,
                   (portal->cplan != NULL), /* protect tree if in plancache */
                   isTopLevel ? PROCESS_UTILITY_TOPLEVEL : PROCESS_UTILITY_QUERY,
                   portal->portalParams,
                   portal->queryEnv,
                   dest,
                   qc);
 
    /* Some utility statements may change context on us */
    MemoryContextSwitchTo(portal->portalContext);
 
    /*
     * Some utility commands (e.g., VACUUM) pop the ActiveSnapshot stack from
     * under us, so don't complain if it's now empty.  Otherwise, our snapshot
     * should be the top one; pop it.  Note that this could be a different
     * snapshot from the one we made above; see EnsurePortalSnapshotExists.
     */
    if (portal->portalSnapshot != NULL && ActiveSnapshotSet())
    {
        Assert(portal->portalSnapshot == GetActiveSnapshot());
        PopActiveSnapshot();
    }
    portal->portalSnapshot = NULL;
}

References ActiveSnapshotSet(), Assert, PortalData::cplan, PortalData::createLevel, generate_unaccent_rules::dest, GetActiveSnapshot(), GetTransactionSnapshot(), PortalData::holdSnapshot, MemoryContextSwitchTo(), PlannedStmtRequiresSnapshot(), PopActiveSnapshot(), PortalData::portalContext, PortalData::portalParams, PortalData::portalSnapshot, PROCESS_UTILITY_QUERY, PROCESS_UTILITY_TOPLEVEL, ProcessUtility(), PushActiveSnapshotWithLevel(), PortalData::queryEnv, RegisterSnapshot(), and PortalData::sourceText.

Referenced by FillPortalStore(), and PortalRunMulti().

PortalSetResultFormat()

void PortalSetResultFormat	(	Portal	portal,
		int	nFormats,
		int16 *	formats
	)

Definition at line 623 of file pquery.c.

{
    int         natts;
    int         i;
 
    /* Do nothing if portal won't return tuples */
    if (portal->tupDesc == NULL)
        return;
    natts = portal->tupDesc->natts;
    portal->formats = (int16 *)
        MemoryContextAlloc(portal->portalContext,
                           natts * sizeof(int16));
    if (nFormats > 1)
    {
        /* format specified for each column */
        if (nFormats != natts)
            ereport(ERROR,
                    (errcode(ERRCODE_PROTOCOL_VIOLATION),
                     errmsg("bind message has %d result formats but query has %d columns",
                            nFormats, natts)));
        memcpy(portal->formats, formats, natts * sizeof(int16));
    }
    else if (nFormats > 0)
    {
        /* single format specified, use for all columns */
        int16       format1 = formats[0];
 
        for (i = 0; i < natts; i++)
            portal->formats[i] = format1;
    }
    else
    {
        /* use default format for all columns */
        for (i = 0; i < natts; i++)
            portal->formats[i] = 0;
    }
}

References ereport, errcode(), errmsg(), ERROR, PortalData::formats, i, MemoryContextAlloc(), TupleDescData::natts, PortalData::portalContext, and PortalData::tupDesc.

Referenced by exec_bind_message(), and exec_simple_query().

PortalStart()

void PortalStart	(	Portal	portal,
		ParamListInfo	params,
		int	eflags,
		Snapshot	snapshot
	)

Definition at line 433 of file pquery.c.

{
    Portal      saveActivePortal;
    ResourceOwner saveResourceOwner;
    MemoryContext savePortalContext;
    MemoryContext oldContext;
    QueryDesc  *queryDesc;
    int         myeflags;
 
    Assert(PortalIsValid(portal));
    Assert(portal->status == PORTAL_DEFINED);
 
    /*
     * Set up global portal context pointers.
     */
    saveActivePortal = ActivePortal;
    saveResourceOwner = CurrentResourceOwner;
    savePortalContext = PortalContext;
    PG_TRY();
    {
        ActivePortal = portal;
        if (portal->resowner)
            CurrentResourceOwner = portal->resowner;
        PortalContext = portal->portalContext;
 
        oldContext = MemoryContextSwitchTo(PortalContext);
 
        /* Must remember portal param list, if any */
        portal->portalParams = params;
 
        /*
         * Determine the portal execution strategy
         */
        portal->strategy = ChoosePortalStrategy(portal->stmts);
 
        /*
         * Fire her up according to the strategy
         */
        switch (portal->strategy)
        {
            case PORTAL_ONE_SELECT:
 
                /* Must set snapshot before starting executor. */
                if (snapshot)
                    PushActiveSnapshot(snapshot);
                else
                    PushActiveSnapshot(GetTransactionSnapshot());
 
                /*
                 * We could remember the snapshot in portal->portalSnapshot,
                 * but presently there seems no need to, as this code path
                 * cannot be used for non-atomic execution.  Hence there can't
                 * be any commit/abort that might destroy the snapshot.  Since
                 * we don't do that, there's also no need to force a
                 * non-default nesting level for the snapshot.
                 */
 
                /*
                 * Create QueryDesc in portal's context; for the moment, set
                 * the destination to DestNone.
                 */
                queryDesc = CreateQueryDesc(linitial_node(PlannedStmt, portal->stmts),
                                            portal->sourceText,
                                            GetActiveSnapshot(),
                                            InvalidSnapshot,
                                            None_Receiver,
                                            params,
                                            portal->queryEnv,
                                            0);
 
                /*
                 * If it's a scrollable cursor, executor needs to support
                 * REWIND and backwards scan, as well as whatever the caller
                 * might've asked for.
                 */
                if (portal->cursorOptions & CURSOR_OPT_SCROLL)
                    myeflags = eflags | EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD;
                else
                    myeflags = eflags;
 
                /*
                 * Call ExecutorStart to prepare the plan for execution
                 */
                ExecutorStart(queryDesc, myeflags);
 
                /*
                 * This tells PortalCleanup to shut down the executor
                 */
                portal->queryDesc = queryDesc;
 
                /*
                 * Remember tuple descriptor (computed by ExecutorStart)
                 */
                portal->tupDesc = queryDesc->tupDesc;
 
                /*
                 * Reset cursor position data to "start of query"
                 */
                portal->atStart = true;
                portal->atEnd = false;  /* allow fetches */
                portal->portalPos = 0;
 
                PopActiveSnapshot();
                break;
 
            case PORTAL_ONE_RETURNING:
            case PORTAL_ONE_MOD_WITH:
 
                /*
                 * We don't start the executor until we are told to run the
                 * portal.  We do need to set up the result tupdesc.
                 */
                {
                    PlannedStmt *pstmt;
 
                    pstmt = PortalGetPrimaryStmt(portal);
                    portal->tupDesc =
                        ExecCleanTypeFromTL(pstmt->planTree->targetlist);
                }
 
                /*
                 * Reset cursor position data to "start of query"
                 */
                portal->atStart = true;
                portal->atEnd = false;  /* allow fetches */
                portal->portalPos = 0;
                break;
 
            case PORTAL_UTIL_SELECT:
 
                /*
                 * We don't set snapshot here, because PortalRunUtility will
                 * take care of it if needed.
                 */
                {
                    PlannedStmt *pstmt = PortalGetPrimaryStmt(portal);
 
                    Assert(pstmt->commandType == CMD_UTILITY);
                    portal->tupDesc = UtilityTupleDescriptor(pstmt->utilityStmt);
                }
 
                /*
                 * Reset cursor position data to "start of query"
                 */
                portal->atStart = true;
                portal->atEnd = false;  /* allow fetches */
                portal->portalPos = 0;
                break;
 
            case PORTAL_MULTI_QUERY:
                /* Need do nothing now */
                portal->tupDesc = NULL;
                break;
        }
    }
    PG_CATCH();
    {
        /* Uncaught error while executing portal: mark it dead */
        MarkPortalFailed(portal);
 
        /* Restore global vars and propagate error */
        ActivePortal = saveActivePortal;
        CurrentResourceOwner = saveResourceOwner;
        PortalContext = savePortalContext;
 
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    MemoryContextSwitchTo(oldContext);
 
    ActivePortal = saveActivePortal;
    CurrentResourceOwner = saveResourceOwner;
    PortalContext = savePortalContext;
 
    portal->status = PORTAL_READY;
}

References ActivePortal, Assert, PortalData::atEnd, PortalData::atStart, ChoosePortalStrategy(), CMD_UTILITY, PlannedStmt::commandType, CreateQueryDesc(), CurrentResourceOwner, CURSOR_OPT_SCROLL, PortalData::cursorOptions, EXEC_FLAG_BACKWARD, EXEC_FLAG_REWIND, ExecCleanTypeFromTL(), ExecutorStart(), GetActiveSnapshot(), GetTransactionSnapshot(), InvalidSnapshot, linitial_node, MarkPortalFailed(), MemoryContextSwitchTo(), None_Receiver, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PlannedStmt::planTree, PopActiveSnapshot(), PORTAL_DEFINED, PORTAL_MULTI_QUERY, PORTAL_ONE_MOD_WITH, PORTAL_ONE_RETURNING, PORTAL_ONE_SELECT, PORTAL_READY, PORTAL_UTIL_SELECT, PortalContext, PortalData::portalContext, PortalGetPrimaryStmt(), PortalIsValid, PortalData::portalParams, PortalData::portalPos, PushActiveSnapshot(), PortalData::queryDesc, PortalData::queryEnv, PortalData::resowner, PortalData::sourceText, PortalData::status, PortalData::stmts, PortalData::strategy, Plan::targetlist, QueryDesc::tupDesc, PortalData::tupDesc, PlannedStmt::utilityStmt, and UtilityTupleDescriptor().

Referenced by exec_bind_message(), exec_simple_query(), ExecuteQuery(), PerformCursorOpen(), and SPI_cursor_open_internal().

ProcessQuery()

static void ProcessQuery ( PlannedStmt *  plan, const char *  sourceText, ParamListInfo  params, QueryEnvironment *  queryEnv, DestReceiver *  dest, QueryCompletion *  qc  )

static

Definition at line 136 of file pquery.c.

{
    QueryDesc  *queryDesc;
 
    /*
     * Create the QueryDesc object
     */
    queryDesc = CreateQueryDesc(plan, sourceText,
                                GetActiveSnapshot(), InvalidSnapshot,
                                dest, params, queryEnv, 0);
 
    /*
     * Call ExecutorStart to prepare the plan for execution
     */
    ExecutorStart(queryDesc, 0);
 
    /*
     * Run the plan to completion.
     */
    ExecutorRun(queryDesc, ForwardScanDirection, 0, true);
 
    /*
     * Build command completion status data, if caller wants one.
     */
    if (qc)
    {
        switch (queryDesc->operation)
        {
            case CMD_SELECT:
                SetQueryCompletion(qc, CMDTAG_SELECT, queryDesc->estate->es_processed);
                break;
            case CMD_INSERT:
                SetQueryCompletion(qc, CMDTAG_INSERT, queryDesc->estate->es_processed);
                break;
            case CMD_UPDATE:
                SetQueryCompletion(qc, CMDTAG_UPDATE, queryDesc->estate->es_processed);
                break;
            case CMD_DELETE:
                SetQueryCompletion(qc, CMDTAG_DELETE, queryDesc->estate->es_processed);
                break;
            case CMD_MERGE:
                SetQueryCompletion(qc, CMDTAG_MERGE, queryDesc->estate->es_processed);
                break;
            default:
                SetQueryCompletion(qc, CMDTAG_UNKNOWN, queryDesc->estate->es_processed);
                break;
        }
    }
 
    /*
     * Now, we close down all the scans and free allocated resources.
     */
    ExecutorFinish(queryDesc);
    ExecutorEnd(queryDesc);
 
    FreeQueryDesc(queryDesc);
}

References CMD_DELETE, CMD_INSERT, CMD_MERGE, CMD_SELECT, CMD_UPDATE, CreateQueryDesc(), generate_unaccent_rules::dest, EState::es_processed, QueryDesc::estate, ExecutorEnd(), ExecutorFinish(), ExecutorRun(), ExecutorStart(), ForwardScanDirection, FreeQueryDesc(), GetActiveSnapshot(), InvalidSnapshot, QueryDesc::operation, plan, and SetQueryCompletion().

Referenced by PortalRunMulti().

RunFromStore()

static uint64 RunFromStore ( Portal  portal, ScanDirection  direction, uint64  count, DestReceiver *  dest  )

static

Definition at line 1061 of file pquery.c.

{
    uint64      current_tuple_count = 0;
    TupleTableSlot *slot;
 
    slot = MakeSingleTupleTableSlot(portal->tupDesc, &TTSOpsMinimalTuple);
 
    dest->rStartup(dest, CMD_SELECT, portal->tupDesc);
 
    if (ScanDirectionIsNoMovement(direction))
    {
        /* do nothing except start/stop the destination */
    }
    else
    {
        bool        forward = ScanDirectionIsForward(direction);
 
        for (;;)
        {
            MemoryContext oldcontext;
            bool        ok;
 
            oldcontext = MemoryContextSwitchTo(portal->holdContext);
 
            ok = tuplestore_gettupleslot(portal->holdStore, forward, false,
                                         slot);
 
            MemoryContextSwitchTo(oldcontext);
 
            if (!ok)
                break;
 
            /*
             * If we are not able to send the tuple, we assume the destination
             * has closed and no more tuples can be sent. If that's the case,
             * end the loop.
             */
            if (!dest->receiveSlot(slot, dest))
                break;
 
            ExecClearTuple(slot);
 
            /*
             * check our tuple count.. if we've processed the proper number
             * then quit, else loop again and process more tuples. Zero count
             * means no limit.
             */
            current_tuple_count++;
            if (count && count == current_tuple_count)
                break;
        }
    }
 
    dest->rShutdown(dest);
 
    ExecDropSingleTupleTableSlot(slot);
 
    return current_tuple_count;
}

References CMD_SELECT, generate_unaccent_rules::dest, ExecClearTuple(), ExecDropSingleTupleTableSlot(), PortalData::holdContext, PortalData::holdStore, MakeSingleTupleTableSlot(), MemoryContextSwitchTo(), ScanDirectionIsForward, ScanDirectionIsNoMovement, TTSOpsMinimalTuple, PortalData::tupDesc, and tuplestore_gettupleslot().

Referenced by PortalRunSelect().

Variable Documentation

ActivePortal

Portal ActivePortal = NULL

Definition at line 35 of file pquery.c.

Referenced by EnsurePortalSnapshotExists(), function_parse_error_transpose(), PersistHoldablePortal(), PortalRun(), PortalRunFetch(), and PortalStart().