#include "nodes/parsenodes.h"
#include "utils/portal.h"

Include dependency graph for pquery.h:

This graph shows which files directly or indirectly include this file:

Typedefs
typedef struct PlannedStmt	PlannedStmt

Functions
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, DestReceiver dest, DestReceiver altdest, QueryCompletion *qc)

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

bool	PlannedStmtRequiresSnapshot (PlannedStmt *pstmt)

void	EnsurePortalSnapshotExists (void)

Variables
PGDLLIMPORT Portal	ActivePortal

Typedef Documentation

◆ PlannedStmt

typedef struct PlannedStmt PlannedStmt

Definition at line 20 of file pquery.h.

Function Documentation

◆ ChoosePortalStrategy()

PortalStrategy ChoosePortalStrategy ( List * stmts )

Definition at line 205 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().

◆ EnsurePortalSnapshotExists()

void EnsurePortalSnapshotExists ( void )

Definition at line 1758 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 322 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 344 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().

◆ PlannedStmtRequiresSnapshot()

bool PlannedStmtRequiresSnapshot ( PlannedStmt * pstmt )

Definition at line 1710 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,
		DestReceiver *	dest,
		DestReceiver *	altdest,
		QueryCompletion *	qc
	)

Definition at line 680 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 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, 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 1372 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);
 
    /*
     * 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::status, and PortalData::strategy.

Referenced by _SPI_cursor_operation(), and PerformPortalFetch().

◆ PortalSetResultFormat()

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

Definition at line 619 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 429 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;
}