[postgresql] / src / backend / executor / execMain.c

/*-------------------------------------------------------------------------
 *
 * execMain.c
 *        top level executor interface routines
 *
 * INTERFACE ROUTINES
 *      ExecutorStart()
 *      ExecutorRun()
 *      ExecutorFinish()
 *      ExecutorEnd()
 *
 *      These four procedures are the external interface to the executor.
 *      In each case, the query descriptor is required as an argument.
 *
 *      ExecutorStart must be called at the beginning of execution of any
 *      query plan and ExecutorEnd must always be called at the end of
 *      execution of a plan (unless it is aborted due to error).
 *
 *      ExecutorRun accepts direction and count arguments that specify whether
 *      the plan is to be executed forwards, backwards, and for how many tuples.
 *      In some cases ExecutorRun may be called multiple times to process all
 *      the tuples for a plan.  It is also acceptable to stop short of executing
 *      the whole plan (but only if it is a SELECT).
 *
 *      ExecutorFinish must be called after the final ExecutorRun call and
 *      before ExecutorEnd.  This can be omitted only in case of EXPLAIN,
 *      which should also omit ExecutorRun.
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        src/backend/executor/execMain.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/reloptions.h"
#include "access/sysattr.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/heap.h"
#include "catalog/namespace.h"
#include "catalog/toasting.h"
#include "commands/tablespace.h"
#include "commands/trigger.h"
#include "executor/execdebug.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "parser/parse_clause.h"
#include "parser/parsetree.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/smgr.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"
#include "utils/tqual.h"


/* Hooks for plugins to get control in ExecutorStart/Run/Finish/End */
ExecutorStart_hook_type ExecutorStart_hook = NULL;
ExecutorRun_hook_type ExecutorRun_hook = NULL;
ExecutorFinish_hook_type ExecutorFinish_hook = NULL;
ExecutorEnd_hook_type ExecutorEnd_hook = NULL;

/* Hook for plugin to get control in ExecCheckRTPerms() */
ExecutorCheckPerms_hook_type ExecutorCheckPerms_hook = NULL;

/* decls for local routines only used within this module */
static void InitPlan(QueryDesc *queryDesc, int eflags);
static void CheckValidRowMarkRel(Relation rel, RowMarkType markType);
static void ExecPostprocessPlan(EState *estate);
static void ExecEndPlan(PlanState *planstate, EState *estate);
static void ExecutePlan(EState *estate, PlanState *planstate,
                        CmdType operation,
                        bool sendTuples,
                        long numberTuples,
                        ScanDirection direction,
                        DestReceiver *dest);
static bool ExecCheckRTEPerms(RangeTblEntry *rte);
static void ExecCheckXactReadOnly(PlannedStmt *plannedstmt);
static char *ExecBuildSlotValueDescription(TupleTableSlot *slot,
                                                                                   int maxfieldlen);
static void EvalPlanQualStart(EPQState *epqstate, EState *parentestate,
                                  Plan *planTree);
static void OpenIntoRel(QueryDesc *queryDesc);
static void CloseIntoRel(QueryDesc *queryDesc);
static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
static void intorel_receive(TupleTableSlot *slot, DestReceiver *self);
static void intorel_shutdown(DestReceiver *self);
static void intorel_destroy(DestReceiver *self);

/* end of local decls */


/* ----------------------------------------------------------------
 *              ExecutorStart
 *
 *              This routine must be called at the beginning of any execution of any
 *              query plan
 *
 * Takes a QueryDesc previously created by CreateQueryDesc (which is separate
 * only because some places use QueryDescs for utility commands).  The tupDesc
 * field of the QueryDesc is filled in to describe the tuples that will be
 * returned, and the internal fields (estate and planstate) are set up.
 *
 * eflags contains flag bits as described in executor.h.
 *
 * NB: the CurrentMemoryContext when this is called will become the parent
 * of the per-query context used for this Executor invocation.
 *
 * We provide a function hook variable that lets loadable plugins
 * get control when ExecutorStart is called.  Such a plugin would
 * normally call standard_ExecutorStart().
 *
 * ----------------------------------------------------------------
 */
void
ExecutorStart(QueryDesc *queryDesc, int eflags)
{
        if (ExecutorStart_hook)
                (*ExecutorStart_hook) (queryDesc, eflags);
        else
                standard_ExecutorStart(queryDesc, eflags);
}

void
standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
{
        EState     *estate;
        MemoryContext oldcontext;

        /* sanity checks: queryDesc must not be started already */
        Assert(queryDesc != NULL);
        Assert(queryDesc->estate == NULL);

        /*
         * If the transaction is read-only, we need to check if any writes are
         * planned to non-temporary tables.  EXPLAIN is considered read-only.
         */
        if (XactReadOnly && !(eflags & EXEC_FLAG_EXPLAIN_ONLY))
                ExecCheckXactReadOnly(queryDesc->plannedstmt);

        /*
         * Build EState, switch into per-query memory context for startup.
         */
        estate = CreateExecutorState();
        queryDesc->estate = estate;

        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        /*
         * Fill in external parameters, if any, from queryDesc; and allocate
         * workspace for internal parameters
         */
        estate->es_param_list_info = queryDesc->params;

        if (queryDesc->plannedstmt->nParamExec > 0)
                estate->es_param_exec_vals = (ParamExecData *)
                        palloc0(queryDesc->plannedstmt->nParamExec * sizeof(ParamExecData));

        /*
         * If non-read-only query, set the command ID to mark output tuples with
         */
        switch (queryDesc->operation)
        {
                case CMD_SELECT:

                        /*
                         * SELECT INTO, SELECT FOR UPDATE/SHARE and modifying CTEs need to
                         * mark tuples
                         */
                        if (queryDesc->plannedstmt->intoClause != NULL ||
                                queryDesc->plannedstmt->rowMarks != NIL ||
                                queryDesc->plannedstmt->hasModifyingCTE)
                                estate->es_output_cid = GetCurrentCommandId(true);

                        /*
                         * A SELECT without modifying CTEs can't possibly queue triggers,
                         * so force skip-triggers mode. This is just a marginal efficiency
                         * hack, since AfterTriggerBeginQuery/AfterTriggerEndQuery aren't
                         * all that expensive, but we might as well do it.
                         */
                        if (!queryDesc->plannedstmt->hasModifyingCTE)
                                eflags |= EXEC_FLAG_SKIP_TRIGGERS;
                        break;

                case CMD_INSERT:
                case CMD_DELETE:
                case CMD_UPDATE:
                        estate->es_output_cid = GetCurrentCommandId(true);
                        break;

                default:
                        elog(ERROR, "unrecognized operation code: %d",
                                 (int) queryDesc->operation);
                        break;
        }

        /*
         * Copy other important information into the EState
         */
        estate->es_snapshot = RegisterSnapshot(queryDesc->snapshot);
        estate->es_crosscheck_snapshot = RegisterSnapshot(queryDesc->crosscheck_snapshot);
        estate->es_top_eflags = eflags;
        estate->es_instrument = queryDesc->instrument_options;

        /*
         * Initialize the plan state tree
         */
        InitPlan(queryDesc, eflags);

        /*
         * Set up an AFTER-trigger statement context, unless told not to, or
         * unless it's EXPLAIN-only mode (when ExecutorFinish won't be called).
         */
        if (!(eflags & (EXEC_FLAG_SKIP_TRIGGERS | EXEC_FLAG_EXPLAIN_ONLY)))
                AfterTriggerBeginQuery();

        MemoryContextSwitchTo(oldcontext);
}

/* ----------------------------------------------------------------
 *              ExecutorRun
 *
 *              This is the main routine of the executor module. It accepts
 *              the query descriptor from the traffic cop and executes the
 *              query plan.
 *
 *              ExecutorStart must have been called already.
 *
 *              If direction is NoMovementScanDirection then nothing is done
 *              except to start up/shut down the destination.  Otherwise,
 *              we retrieve up to 'count' tuples in the specified direction.
 *
 *              Note: count = 0 is interpreted as no portal limit, i.e., run to
 *              completion.
 *
 *              There is no return value, but output tuples (if any) are sent to
 *              the destination receiver specified in the QueryDesc; and the number
 *              of tuples processed at the top level can be found in
 *              estate->es_processed.
 *
 *              We provide a function hook variable that lets loadable plugins
 *              get control when ExecutorRun is called.  Such a plugin would
 *              normally call standard_ExecutorRun().
 *
 * ----------------------------------------------------------------
 */
void
ExecutorRun(QueryDesc *queryDesc,
                        ScanDirection direction, long count)
{
        if (ExecutorRun_hook)
                (*ExecutorRun_hook) (queryDesc, direction, count);
        else
                standard_ExecutorRun(queryDesc, direction, count);
}

void
standard_ExecutorRun(QueryDesc *queryDesc,
                                         ScanDirection direction, long count)
{
        EState     *estate;
        CmdType         operation;
        DestReceiver *dest;
        bool            sendTuples;
        MemoryContext oldcontext;

        /* sanity checks */
        Assert(queryDesc != NULL);

        estate = queryDesc->estate;

        Assert(estate != NULL);
        Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));

        /*
         * Switch into per-query memory context
         */
        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        /* Allow instrumentation of Executor overall runtime */
        if (queryDesc->totaltime)
                InstrStartNode(queryDesc->totaltime);

        /*
         * extract information from the query descriptor and the query feature.
         */
        operation = queryDesc->operation;
        dest = queryDesc->dest;

        /*
         * startup tuple receiver, if we will be emitting tuples
         */
        estate->es_processed = 0;
        estate->es_lastoid = InvalidOid;

        sendTuples = (operation == CMD_SELECT ||
                                  queryDesc->plannedstmt->hasReturning);

        if (sendTuples)
                (*dest->rStartup) (dest, operation, queryDesc->tupDesc);

        /*
         * if it's CREATE TABLE AS ... WITH NO DATA, skip plan execution
         */
        if (estate->es_select_into &&
                queryDesc->plannedstmt->intoClause->skipData)
                direction = NoMovementScanDirection;

        /*
         * run plan
         */
        if (!ScanDirectionIsNoMovement(direction))
                ExecutePlan(estate,
                                        queryDesc->planstate,
                                        operation,
                                        sendTuples,
                                        count,
                                        direction,
                                        dest);

        /*
         * shutdown tuple receiver, if we started it
         */
        if (sendTuples)
                (*dest->rShutdown) (dest);

        if (queryDesc->totaltime)
                InstrStopNode(queryDesc->totaltime, estate->es_processed);

        MemoryContextSwitchTo(oldcontext);
}

/* ----------------------------------------------------------------
 *              ExecutorFinish
 *
 *              This routine must be called after the last ExecutorRun call.
 *              It performs cleanup such as firing AFTER triggers.      It is
 *              separate from ExecutorEnd because EXPLAIN ANALYZE needs to
 *              include these actions in the total runtime.
 *
 *              We provide a function hook variable that lets loadable plugins
 *              get control when ExecutorFinish is called.      Such a plugin would
 *              normally call standard_ExecutorFinish().
 *
 * ----------------------------------------------------------------
 */
void
ExecutorFinish(QueryDesc *queryDesc)
{
        if (ExecutorFinish_hook)
                (*ExecutorFinish_hook) (queryDesc);
        else
                standard_ExecutorFinish(queryDesc);
}

void
standard_ExecutorFinish(QueryDesc *queryDesc)
{
        EState     *estate;
        MemoryContext oldcontext;

        /* sanity checks */
        Assert(queryDesc != NULL);

        estate = queryDesc->estate;

        Assert(estate != NULL);
        Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));

        /* This should be run once and only once per Executor instance */
        Assert(!estate->es_finished);

        /* Switch into per-query memory context */
        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        /* Allow instrumentation of Executor overall runtime */
        if (queryDesc->totaltime)
                InstrStartNode(queryDesc->totaltime);

        /* Run ModifyTable nodes to completion */
        ExecPostprocessPlan(estate);

        /* Execute queued AFTER triggers, unless told not to */
        if (!(estate->es_top_eflags & EXEC_FLAG_SKIP_TRIGGERS))
                AfterTriggerEndQuery(estate);

        if (queryDesc->totaltime)
                InstrStopNode(queryDesc->totaltime, 0);

        MemoryContextSwitchTo(oldcontext);

        estate->es_finished = true;
}

/* ----------------------------------------------------------------
 *              ExecutorEnd
 *
 *              This routine must be called at the end of execution of any
 *              query plan
 *
 *              We provide a function hook variable that lets loadable plugins
 *              get control when ExecutorEnd is called.  Such a plugin would
 *              normally call standard_ExecutorEnd().
 *
 * ----------------------------------------------------------------
 */
void
ExecutorEnd(QueryDesc *queryDesc)
{
        if (ExecutorEnd_hook)
                (*ExecutorEnd_hook) (queryDesc);
        else
                standard_ExecutorEnd(queryDesc);
}

void
standard_ExecutorEnd(QueryDesc *queryDesc)
{
        EState     *estate;
        MemoryContext oldcontext;

        /* sanity checks */
        Assert(queryDesc != NULL);

        estate = queryDesc->estate;

        Assert(estate != NULL);

        /*
         * Check that ExecutorFinish was called, unless in EXPLAIN-only mode. This
         * Assert is needed because ExecutorFinish is new as of 9.1, and callers
         * might forget to call it.
         */
        Assert(estate->es_finished ||
                   (estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));

        /*
         * Switch into per-query memory context to run ExecEndPlan
         */
        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        ExecEndPlan(queryDesc->planstate, estate);

        /*
         * Close the SELECT INTO relation if any
         */
        if (estate->es_select_into)
                CloseIntoRel(queryDesc);

        /* do away with our snapshots */
        UnregisterSnapshot(estate->es_snapshot);
        UnregisterSnapshot(estate->es_crosscheck_snapshot);

        /*
         * Must switch out of context before destroying it
         */
        MemoryContextSwitchTo(oldcontext);

        /*
         * Release EState and per-query memory context.  This should release
         * everything the executor has allocated.
         */
        FreeExecutorState(estate);

        /* Reset queryDesc fields that no longer point to anything */
        queryDesc->tupDesc = NULL;
        queryDesc->estate = NULL;
        queryDesc->planstate = NULL;
        queryDesc->totaltime = NULL;
}

/* ----------------------------------------------------------------
 *              ExecutorRewind
 *
 *              This routine may be called on an open queryDesc to rewind it
 *              to the start.
 * ----------------------------------------------------------------
 */
void
ExecutorRewind(QueryDesc *queryDesc)
{
        EState     *estate;
        MemoryContext oldcontext;

        /* sanity checks */
        Assert(queryDesc != NULL);

        estate = queryDesc->estate;

        Assert(estate != NULL);

        /* It's probably not sensible to rescan updating queries */
        Assert(queryDesc->operation == CMD_SELECT);

        /*
         * Switch into per-query memory context
         */
        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        /*
         * rescan plan
         */
        ExecReScan(queryDesc->planstate);

        MemoryContextSwitchTo(oldcontext);
}


/*
 * ExecCheckRTPerms
 *              Check access permissions for all relations listed in a range table.
 *
 * Returns true if permissions are adequate.  Otherwise, throws an appropriate
 * error if ereport_on_violation is true, or simply returns false otherwise.
 */
bool
ExecCheckRTPerms(List *rangeTable, bool ereport_on_violation)
{
        ListCell   *l;
        bool            result = true;

        foreach(l, rangeTable)
        {
                RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);

                result = ExecCheckRTEPerms(rte);
                if (!result)
                {
                        Assert(rte->rtekind == RTE_RELATION);
                        if (ereport_on_violation)
                                aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_CLASS,
                                                           get_rel_name(rte->relid));
                        return false;
                }
        }

        if (ExecutorCheckPerms_hook)
                result = (*ExecutorCheckPerms_hook) (rangeTable,
                                                                                         ereport_on_violation);
        return result;
}

/*
 * ExecCheckRTEPerms
 *              Check access permissions for a single RTE.
 */
static bool
ExecCheckRTEPerms(RangeTblEntry *rte)
{
        AclMode         requiredPerms;
        AclMode         relPerms;
        AclMode         remainingPerms;
        Oid                     relOid;
        Oid                     userid;
        Bitmapset  *tmpset;
        int                     col;

        /*
         * Only plain-relation RTEs need to be checked here.  Function RTEs are
         * checked by init_fcache when the function is prepared for execution.
         * Join, subquery, and special RTEs need no checks.
         */
        if (rte->rtekind != RTE_RELATION)
                return true;

        /*
         * No work if requiredPerms is empty.
         */
        requiredPerms = rte->requiredPerms;
        if (requiredPerms == 0)
                return true;

        relOid = rte->relid;

        /*
         * userid to check as: current user unless we have a setuid indication.
         *
         * Note: GetUserId() is presently fast enough that there's no harm in
         * calling it separately for each RTE.  If that stops being true, we could
         * call it once in ExecCheckRTPerms and pass the userid down from there.
         * But for now, no need for the extra clutter.
         */
        userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();

        /*
         * We must have *all* the requiredPerms bits, but some of the bits can be
         * satisfied from column-level rather than relation-level permissions.
         * First, remove any bits that are satisfied by relation permissions.
         */
        relPerms = pg_class_aclmask(relOid, userid, requiredPerms, ACLMASK_ALL);
        remainingPerms = requiredPerms & ~relPerms;
        if (remainingPerms != 0)
        {
                /*
                 * If we lack any permissions that exist only as relation permissions,
                 * we can fail straight away.
                 */
                if (remainingPerms & ~(ACL_SELECT | ACL_INSERT | ACL_UPDATE))
                        return false;

                /*
                 * Check to see if we have the needed privileges at column level.
                 *
                 * Note: failures just report a table-level error; it would be nicer
                 * to report a column-level error if we have some but not all of the
                 * column privileges.
                 */
                if (remainingPerms & ACL_SELECT)
                {
                        /*
                         * When the query doesn't explicitly reference any columns (for
                         * example, SELECT COUNT(*) FROM table), allow the query if we
                         * have SELECT on any column of the rel, as per SQL spec.
                         */
                        if (bms_is_empty(rte->selectedCols))
                        {
                                if (pg_attribute_aclcheck_all(relOid, userid, ACL_SELECT,
                                                                                          ACLMASK_ANY) != ACLCHECK_OK)
                                        return false;
                        }

                        tmpset = bms_copy(rte->selectedCols);
                        while ((col = bms_first_member(tmpset)) >= 0)
                        {
                                /* remove the column number offset */
                                col += FirstLowInvalidHeapAttributeNumber;
                                if (col == InvalidAttrNumber)
                                {
                                        /* Whole-row reference, must have priv on all cols */
                                        if (pg_attribute_aclcheck_all(relOid, userid, ACL_SELECT,
                                                                                                  ACLMASK_ALL) != ACLCHECK_OK)
                                                return false;
                                }
                                else
                                {
                                        if (pg_attribute_aclcheck(relOid, col, userid,
                                                                                          ACL_SELECT) != ACLCHECK_OK)
                                                return false;
                                }
                        }
                        bms_free(tmpset);
                }

                /*
                 * Basically the same for the mod columns, with either INSERT or
                 * UPDATE privilege as specified by remainingPerms.
                 */
                remainingPerms &= ~ACL_SELECT;
                if (remainingPerms != 0)
                {
                        /*
                         * When the query doesn't explicitly change any columns, allow the
                         * query if we have permission on any column of the rel.  This is
                         * to handle SELECT FOR UPDATE as well as possible corner cases in
                         * INSERT and UPDATE.
                         */
                        if (bms_is_empty(rte->modifiedCols))
                        {
                                if (pg_attribute_aclcheck_all(relOid, userid, remainingPerms,
                                                                                          ACLMASK_ANY) != ACLCHECK_OK)
                                        return false;
                        }

                        tmpset = bms_copy(rte->modifiedCols);
                        while ((col = bms_first_member(tmpset)) >= 0)
                        {
                                /* remove the column number offset */
                                col += FirstLowInvalidHeapAttributeNumber;
                                if (col == InvalidAttrNumber)
                                {
                                        /* whole-row reference can't happen here */
                                        elog(ERROR, "whole-row update is not implemented");
                                }
                                else
                                {
                                        if (pg_attribute_aclcheck(relOid, col, userid,
                                                                                          remainingPerms) != ACLCHECK_OK)
                                                return false;
                                }
                        }
                        bms_free(tmpset);
                }
        }
        return true;
}

/*
 * Check that the query does not imply any writes to non-temp tables.
 *
 * Note: in a Hot Standby slave this would need to reject writes to temp
 * tables as well; but an HS slave can't have created any temp tables
 * in the first place, so no need to check that.
 */
static void
ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
{
        ListCell   *l;

        /*
         * CREATE TABLE AS or SELECT INTO?
         *
         * XXX should we allow this if the destination is temp?  Considering that
         * it would still require catalog changes, probably not.
         */
        if (plannedstmt->intoClause != NULL)
                PreventCommandIfReadOnly(CreateCommandTag((Node *) plannedstmt));

        /* Fail if write permissions are requested on any non-temp table */
        foreach(l, plannedstmt->rtable)
        {
                RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);

                if (rte->rtekind != RTE_RELATION)
                        continue;

                if ((rte->requiredPerms & (~ACL_SELECT)) == 0)
                        continue;

                if (isTempNamespace(get_rel_namespace(rte->relid)))
                        continue;

                PreventCommandIfReadOnly(CreateCommandTag((Node *) plannedstmt));
        }
}


/* ----------------------------------------------------------------
 *              InitPlan
 *
 *              Initializes the query plan: open files, allocate storage
 *              and start up the rule manager
 * ----------------------------------------------------------------
 */
static void
InitPlan(QueryDesc *queryDesc, int eflags)
{
        CmdType         operation = queryDesc->operation;
        PlannedStmt *plannedstmt = queryDesc->plannedstmt;
        Plan       *plan = plannedstmt->planTree;
        List       *rangeTable = plannedstmt->rtable;
        EState     *estate = queryDesc->estate;
        PlanState  *planstate;
        TupleDesc       tupType;
        ListCell   *l;
        int                     i;

        /*
         * Do permissions checks
         */
        ExecCheckRTPerms(rangeTable, true);

        /*
         * initialize the node's execution state
         */
        estate->es_range_table = rangeTable;
        estate->es_plannedstmt = plannedstmt;

        /*
         * initialize result relation stuff, and open/lock the result rels.
         *
         * We must do this before initializing the plan tree, else we might try to
         * do a lock upgrade if a result rel is also a source rel.
         */
        if (plannedstmt->resultRelations)
        {
                List       *resultRelations = plannedstmt->resultRelations;
                int                     numResultRelations = list_length(resultRelations);
                ResultRelInfo *resultRelInfos;
                ResultRelInfo *resultRelInfo;

                resultRelInfos = (ResultRelInfo *)
                        palloc(numResultRelations * sizeof(ResultRelInfo));
                resultRelInfo = resultRelInfos;
                foreach(l, resultRelations)
                {
                        Index           resultRelationIndex = lfirst_int(l);
                        Oid                     resultRelationOid;
                        Relation        resultRelation;

                        resultRelationOid = getrelid(resultRelationIndex, rangeTable);
                        resultRelation = heap_open(resultRelationOid, RowExclusiveLock);
                        InitResultRelInfo(resultRelInfo,
                                                          resultRelation,
                                                          resultRelationIndex,
                                                          estate->es_instrument);
                        resultRelInfo++;
                }
                estate->es_result_relations = resultRelInfos;
                estate->es_num_result_relations = numResultRelations;
                /* es_result_relation_info is NULL except when within ModifyTable */
                estate->es_result_relation_info = NULL;
        }
        else
        {
                /*
                 * if no result relation, then set state appropriately
                 */
                estate->es_result_relations = NULL;
                estate->es_num_result_relations = 0;
                estate->es_result_relation_info = NULL;
        }

        /*
         * Similarly, we have to lock relations selected FOR UPDATE/FOR SHARE
         * before we initialize the plan tree, else we'd be risking lock upgrades.
         * While we are at it, build the ExecRowMark list.
         */
        estate->es_rowMarks = NIL;
        foreach(l, plannedstmt->rowMarks)
        {
                PlanRowMark *rc = (PlanRowMark *) lfirst(l);
                Oid                     relid;
                Relation        relation;
                ExecRowMark *erm;

                /* ignore "parent" rowmarks; they are irrelevant at runtime */
                if (rc->isParent)
                        continue;

                switch (rc->markType)
                {
                        case ROW_MARK_EXCLUSIVE:
                        case ROW_MARK_SHARE:
                                relid = getrelid(rc->rti, rangeTable);
                                relation = heap_open(relid, RowShareLock);
                                break;
                        case ROW_MARK_REFERENCE:
                                relid = getrelid(rc->rti, rangeTable);
                                relation = heap_open(relid, AccessShareLock);
                                break;
                        case ROW_MARK_COPY:
                                /* there's no real table here ... */
                                relation = NULL;
                                break;
                        default:
                                elog(ERROR, "unrecognized markType: %d", rc->markType);
                                relation = NULL;        /* keep compiler quiet */
                                break;
                }

                /* Check that relation is a legal target for marking */
                if (relation)
                        CheckValidRowMarkRel(relation, rc->markType);

                erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
                erm->relation = relation;
                erm->rti = rc->rti;
                erm->prti = rc->prti;
                erm->rowmarkId = rc->rowmarkId;
                erm->markType = rc->markType;
                erm->noWait = rc->noWait;
                ItemPointerSetInvalid(&(erm->curCtid));
                estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
        }

        /*
         * Detect whether we're doing SELECT INTO.  If so, set the es_into_oids
         * flag appropriately so that the plan tree will be initialized with the
         * correct tuple descriptors.  (Other SELECT INTO stuff comes later.)
         */
        estate->es_select_into = false;
        if (operation == CMD_SELECT && plannedstmt->intoClause != NULL)
        {
                estate->es_select_into = true;
                estate->es_into_oids = interpretOidsOption(plannedstmt->intoClause->options);
        }

        /*
         * Initialize the executor's tuple table to empty.
         */
        estate->es_tupleTable = NIL;
        estate->es_trig_tuple_slot = NULL;
        estate->es_trig_oldtup_slot = NULL;
        estate->es_trig_newtup_slot = NULL;

        /* mark EvalPlanQual not active */
        estate->es_epqTuple = NULL;
        estate->es_epqTupleSet = NULL;
        estate->es_epqScanDone = NULL;

        /*
         * Initialize private state information for each SubPlan.  We must do this
         * before running ExecInitNode on the main query tree, since
         * ExecInitSubPlan expects to be able to find these entries.
         */
        Assert(estate->es_subplanstates == NIL);
        i = 1;                                          /* subplan indices count from 1 */
        foreach(l, plannedstmt->subplans)
        {
                Plan       *subplan = (Plan *) lfirst(l);
                PlanState  *subplanstate;
                int                     sp_eflags;

                /*
                 * A subplan will never need to do BACKWARD scan nor MARK/RESTORE. If
                 * it is a parameterless subplan (not initplan), we suggest that it be
                 * prepared to handle REWIND efficiently; otherwise there is no need.
                 */
                sp_eflags = eflags & EXEC_FLAG_EXPLAIN_ONLY;
                if (bms_is_member(i, plannedstmt->rewindPlanIDs))
                        sp_eflags |= EXEC_FLAG_REWIND;

                subplanstate = ExecInitNode(subplan, estate, sp_eflags);

                estate->es_subplanstates = lappend(estate->es_subplanstates,
                                                                                   subplanstate);

                i++;
        }

        /*
         * Initialize the private state information for all the nodes in the query
         * tree.  This opens files, allocates storage and leaves us ready to start
         * processing tuples.
         */
        planstate = ExecInitNode(plan, estate, eflags);

        /*
         * Get the tuple descriptor describing the type of tuples to return. (this
         * is especially important if we are creating a relation with "SELECT
         * INTO")
         */
        tupType = ExecGetResultType(planstate);

        /*
         * Initialize the junk filter if needed.  SELECT queries need a filter if
         * there are any junk attrs in the top-level tlist.
         */
        if (operation == CMD_SELECT)
        {
                bool            junk_filter_needed = false;
                ListCell   *tlist;

                foreach(tlist, plan->targetlist)
                {
                        TargetEntry *tle = (TargetEntry *) lfirst(tlist);

                        if (tle->resjunk)
                        {
                                junk_filter_needed = true;
                                break;
                        }
                }

                if (junk_filter_needed)
                {
                        JunkFilter *j;

                        j = ExecInitJunkFilter(planstate->plan->targetlist,
                                                                   tupType->tdhasoid,
                                                                   ExecInitExtraTupleSlot(estate));
                        estate->es_junkFilter = j;

                        /* Want to return the cleaned tuple type */
                        tupType = j->jf_cleanTupType;
                }
        }

        queryDesc->tupDesc = tupType;
        queryDesc->planstate = planstate;

        /*
         * If doing SELECT INTO, initialize the "into" relation.  We must wait
         * till now so we have the "clean" result tuple type to create the new
         * table from.
         *
         * If EXPLAIN, skip creating the "into" relation.
         */
        if (estate->es_select_into && !(eflags & EXEC_FLAG_EXPLAIN_ONLY))
                OpenIntoRel(queryDesc);
}

/*
 * Check that a proposed result relation is a legal target for the operation
 *
 * In most cases parser and/or planner should have noticed this already, but
 * let's make sure.  In the view case we do need a test here, because if the
 * view wasn't rewritten by a rule, it had better have an INSTEAD trigger.
 *
 * Note: when changing this function, you probably also need to look at
 * CheckValidRowMarkRel.
 */
void
CheckValidResultRel(Relation resultRel, CmdType operation)
{
        TriggerDesc *trigDesc = resultRel->trigdesc;

        switch (resultRel->rd_rel->relkind)
        {
                case RELKIND_RELATION:
                        /* OK */
                        break;
                case RELKIND_SEQUENCE:
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot change sequence \"%s\"",
                                                        RelationGetRelationName(resultRel))));
                        break;
                case RELKIND_TOASTVALUE:
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot change TOAST relation \"%s\"",
                                                        RelationGetRelationName(resultRel))));
                        break;
                case RELKIND_VIEW:
                        switch (operation)
                        {
                                case CMD_INSERT:
                                        if (!trigDesc || !trigDesc->trig_insert_instead_row)
                                                ereport(ERROR,
                                                  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                                   errmsg("cannot insert into view \"%s\"",
                                                                  RelationGetRelationName(resultRel)),
                                                   errhint("You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.")));
                                        break;
                                case CMD_UPDATE:
                                        if (!trigDesc || !trigDesc->trig_update_instead_row)
                                                ereport(ERROR,
                                                  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                                   errmsg("cannot update view \"%s\"",
                                                                  RelationGetRelationName(resultRel)),
                                                   errhint("You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.")));
                                        break;
                                case CMD_DELETE:
                                        if (!trigDesc || !trigDesc->trig_delete_instead_row)
                                                ereport(ERROR,
                                                  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                                   errmsg("cannot delete from view \"%s\"",
                                                                  RelationGetRelationName(resultRel)),
                                                   errhint("You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.")));
                                        break;
                                default:
                                        elog(ERROR, "unrecognized CmdType: %d", (int) operation);
                                        break;
                        }
                        break;
                case RELKIND_FOREIGN_TABLE:
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot change foreign table \"%s\"",
                                                        RelationGetRelationName(resultRel))));
                        break;
                default:
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot change relation \"%s\"",
                                                        RelationGetRelationName(resultRel))));
                        break;
        }
}

/*
 * Check that a proposed rowmark target relation is a legal target
 *
 * In most cases parser and/or planner should have noticed this already, but
 * they don't cover all cases.
 */
static void
CheckValidRowMarkRel(Relation rel, RowMarkType markType)
{
        switch (rel->rd_rel->relkind)
        {
                case RELKIND_RELATION:
                        /* OK */
                        break;
                case RELKIND_SEQUENCE:
                        /* Must disallow this because we don't vacuum sequences */
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot lock rows in sequence \"%s\"",
                                                        RelationGetRelationName(rel))));
                        break;
                case RELKIND_TOASTVALUE:
                        /* We could allow this, but there seems no good reason to */
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot lock rows in TOAST relation \"%s\"",
                                                        RelationGetRelationName(rel))));
                        break;
                case RELKIND_VIEW:
                        /* Should not get here */
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot lock rows in view \"%s\"",
                                                        RelationGetRelationName(rel))));
                        break;
                case RELKIND_FOREIGN_TABLE:
                        /* Perhaps we can support this someday, but not today */
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot lock rows in foreign table \"%s\"",
                                                        RelationGetRelationName(rel))));
                        break;
                default:
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("cannot lock rows in relation \"%s\"",
                                                        RelationGetRelationName(rel))));
                        break;
        }
}

/*
 * Initialize ResultRelInfo data for one result relation
 *
 * Caution: before Postgres 9.1, this function included the relkind checking
 * that's now in CheckValidResultRel, and it also did ExecOpenIndices if
 * appropriate.  Be sure callers cover those needs.
 */
void
InitResultRelInfo(ResultRelInfo *resultRelInfo,
                                  Relation resultRelationDesc,
                                  Index resultRelationIndex,
                                  int instrument_options)
{
        MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
        resultRelInfo->type = T_ResultRelInfo;
        resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
        resultRelInfo->ri_RelationDesc = resultRelationDesc;
        resultRelInfo->ri_NumIndices = 0;
        resultRelInfo->ri_IndexRelationDescs = NULL;
        resultRelInfo->ri_IndexRelationInfo = NULL;
        /* make a copy so as not to depend on relcache info not changing... */
        resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
        if (resultRelInfo->ri_TrigDesc)
        {
                int                     n = resultRelInfo->ri_TrigDesc->numtriggers;

                resultRelInfo->ri_TrigFunctions = (FmgrInfo *)
                        palloc0(n * sizeof(FmgrInfo));
                resultRelInfo->ri_TrigWhenExprs = (List **)
                        palloc0(n * sizeof(List *));
                if (instrument_options)
                        resultRelInfo->ri_TrigInstrument = InstrAlloc(n, instrument_options);
        }
        else
        {
                resultRelInfo->ri_TrigFunctions = NULL;
                resultRelInfo->ri_TrigWhenExprs = NULL;
                resultRelInfo->ri_TrigInstrument = NULL;
        }
        resultRelInfo->ri_ConstraintExprs = NULL;
        resultRelInfo->ri_junkFilter = NULL;
        resultRelInfo->ri_projectReturning = NULL;
}

/*
 *              ExecGetTriggerResultRel
 *
 * Get a ResultRelInfo for a trigger target relation.  Most of the time,
 * triggers are fired on one of the result relations of the query, and so
 * we can just return a member of the es_result_relations array.  (Note: in
 * self-join situations there might be multiple members with the same OID;
 * if so it doesn't matter which one we pick.)  However, it is sometimes
 * necessary to fire triggers on other relations; this happens mainly when an
 * RI update trigger queues additional triggers on other relations, which will
 * be processed in the context of the outer query.      For efficiency's sake,
 * we want to have a ResultRelInfo for those triggers too; that can avoid
 * repeated re-opening of the relation.  (It also provides a way for EXPLAIN
 * ANALYZE to report the runtimes of such triggers.)  So we make additional
 * ResultRelInfo's as needed, and save them in es_trig_target_relations.
 */
ResultRelInfo *
ExecGetTriggerResultRel(EState *estate, Oid relid)
{
        ResultRelInfo *rInfo;
        int                     nr;
        ListCell   *l;
        Relation        rel;
        MemoryContext oldcontext;

        /* First, search through the query result relations */
        rInfo = estate->es_result_relations;
        nr = estate->es_num_result_relations;
        while (nr > 0)
        {
                if (RelationGetRelid(rInfo->ri_RelationDesc) == relid)
                        return rInfo;
                rInfo++;
                nr--;
        }
        /* Nope, but maybe we already made an extra ResultRelInfo for it */
        foreach(l, estate->es_trig_target_relations)
        {
                rInfo = (ResultRelInfo *) lfirst(l);
                if (RelationGetRelid(rInfo->ri_RelationDesc) == relid)
                        return rInfo;
        }
        /* Nope, so we need a new one */

        /*
         * Open the target relation's relcache entry.  We assume that an
         * appropriate lock is still held by the backend from whenever the trigger
         * event got queued, so we need take no new lock here.  Also, we need not
         * recheck the relkind, so no need for CheckValidResultRel.
         */
        rel = heap_open(relid, NoLock);

        /*
         * Make the new entry in the right context.
         */
        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
        rInfo = makeNode(ResultRelInfo);
        InitResultRelInfo(rInfo,
                                          rel,
                                          0,            /* dummy rangetable index */
                                          estate->es_instrument);
        estate->es_trig_target_relations =
                lappend(estate->es_trig_target_relations, rInfo);
        MemoryContextSwitchTo(oldcontext);

        /*
         * Currently, we don't need any index information in ResultRelInfos used
         * only for triggers, so no need to call ExecOpenIndices.
         */

        return rInfo;
}

/*
 *              ExecContextForcesOids
 *
 * This is pretty grotty: when doing INSERT, UPDATE, or SELECT INTO,
 * we need to ensure that result tuples have space for an OID iff they are
 * going to be stored into a relation that has OIDs.  In other contexts
 * we are free to choose whether to leave space for OIDs in result tuples
 * (we generally don't want to, but we do if a physical-tlist optimization
 * is possible).  This routine checks the plan context and returns TRUE if the
 * choice is forced, FALSE if the choice is not forced.  In the TRUE case,
 * *hasoids is set to the required value.
 *
 * One reason this is ugly is that all plan nodes in the plan tree will emit
 * tuples with space for an OID, though we really only need the topmost node
 * to do so.  However, node types like Sort don't project new tuples but just
 * return their inputs, and in those cases the requirement propagates down
 * to the input node.  Eventually we might make this code smart enough to
 * recognize how far down the requirement really goes, but for now we just
 * make all plan nodes do the same thing if the top level forces the choice.
 *
 * We assume that if we are generating tuples for INSERT or UPDATE,
 * estate->es_result_relation_info is already set up to describe the target
 * relation.  Note that in an UPDATE that spans an inheritance tree, some of
 * the target relations may have OIDs and some not.  We have to make the
 * decisions on a per-relation basis as we initialize each of the subplans of
 * the ModifyTable node, so ModifyTable has to set es_result_relation_info
 * while initializing each subplan.
 *
 * SELECT INTO is even uglier, because we don't have the INTO relation's
 * descriptor available when this code runs; we have to look aside at a
 * flag set by InitPlan().
 */
bool
ExecContextForcesOids(PlanState *planstate, bool *hasoids)
{
        ResultRelInfo *ri = planstate->state->es_result_relation_info;

        if (ri != NULL)
        {
                Relation        rel = ri->ri_RelationDesc;

                if (rel != NULL)
                {
                        *hasoids = rel->rd_rel->relhasoids;
                        return true;
                }
        }

        if (planstate->state->es_select_into)
        {
                *hasoids = planstate->state->es_into_oids;
                return true;
        }

        return false;
}

/* ----------------------------------------------------------------
 *              ExecPostprocessPlan
 *
 *              Give plan nodes a final chance to execute before shutdown
 * ----------------------------------------------------------------
 */
static void
ExecPostprocessPlan(EState *estate)
{
        ListCell   *lc;

        /*
         * Make sure nodes run forward.
         */
        estate->es_direction = ForwardScanDirection;

        /*
         * Run any secondary ModifyTable nodes to completion, in case the main
         * query did not fetch all rows from them.      (We do this to ensure that
         * such nodes have predictable results.)
         */
        foreach(lc, estate->es_auxmodifytables)
        {
                PlanState  *ps = (PlanState *) lfirst(lc);

                for (;;)
                {
                        TupleTableSlot *slot;

                        /* Reset the per-output-tuple exprcontext each time */
                        ResetPerTupleExprContext(estate);

                        slot = ExecProcNode(ps);

                        if (TupIsNull(slot))
                                break;
                }
        }
}

/* ----------------------------------------------------------------
 *              ExecEndPlan
 *
 *              Cleans up the query plan -- closes files and frees up storage
 *
 * NOTE: we are no longer very worried about freeing storage per se
 * in this code; FreeExecutorState should be guaranteed to release all
 * memory that needs to be released.  What we are worried about doing
 * is closing relations and dropping buffer pins.  Thus, for example,
 * tuple tables must be cleared or dropped to ensure pins are released.
 * ----------------------------------------------------------------
 */
static void
ExecEndPlan(PlanState *planstate, EState *estate)
{
        ResultRelInfo *resultRelInfo;
        int                     i;
        ListCell   *l;

        /*
         * shut down the node-type-specific query processing
         */
        ExecEndNode(planstate);

        /*
         * for subplans too
         */
        foreach(l, estate->es_subplanstates)
        {
                PlanState  *subplanstate = (PlanState *) lfirst(l);

                ExecEndNode(subplanstate);
        }

        /*
         * destroy the executor's tuple table.  Actually we only care about
         * releasing buffer pins and tupdesc refcounts; there's no need to pfree
         * the TupleTableSlots, since the containing memory context is about to go
         * away anyway.
         */
        ExecResetTupleTable(estate->es_tupleTable, false);

        /*
         * close the result relation(s) if any, but hold locks until xact commit.
         */
        resultRelInfo = estate->es_result_relations;
        for (i = estate->es_num_result_relations; i > 0; i--)
        {
                /* Close indices and then the relation itself */
                ExecCloseIndices(resultRelInfo);
                heap_close(resultRelInfo->ri_RelationDesc, NoLock);
                resultRelInfo++;
        }

        /*
         * likewise close any trigger target relations
         */
        foreach(l, estate->es_trig_target_relations)
        {
                resultRelInfo = (ResultRelInfo *) lfirst(l);
                /* Close indices and then the relation itself */
                ExecCloseIndices(resultRelInfo);
                heap_close(resultRelInfo->ri_RelationDesc, NoLock);
        }

        /*
         * close any relations selected FOR UPDATE/FOR SHARE, again keeping locks
         */
        foreach(l, estate->es_rowMarks)
        {
                ExecRowMark *erm = (ExecRowMark *) lfirst(l);

                if (erm->relation)
                        heap_close(erm->relation, NoLock);
        }
}

/* ----------------------------------------------------------------
 *              ExecutePlan
 *
 *              Processes the query plan until we have processed 'numberTuples' tuples,
 *              moving in the specified direction.
 *
 *              Runs to completion if numberTuples is 0
 *
 * Note: the ctid attribute is a 'junk' attribute that is removed before the
 * user can see it
 * ----------------------------------------------------------------
 */
static void
ExecutePlan(EState *estate,
                        PlanState *planstate,
                        CmdType operation,
                        bool sendTuples,
                        long numberTuples,
                        ScanDirection direction,
                        DestReceiver *dest)
{
        TupleTableSlot *slot;
        long            current_tuple_count;

        /*
         * initialize local variables
         */
        current_tuple_count = 0;

        /*
         * Set the direction.
         */
        estate->es_direction = direction;

        /*
         * Loop until we've processed the proper number of tuples from the plan.
         */
        for (;;)
        {
                /* Reset the per-output-tuple exprcontext */
                ResetPerTupleExprContext(estate);

                /*
                 * Execute the plan and obtain a tuple
                 */
                slot = ExecProcNode(planstate);

                /*
                 * if the tuple is null, then we assume there is nothing more to
                 * process so we just end the loop...
                 */
                if (TupIsNull(slot))
                        break;

                /*
                 * If we have a junk filter, then project a new tuple with the junk
                 * removed.
                 *
                 * Store this new "clean" tuple in the junkfilter's resultSlot.
                 * (Formerly, we stored it back over the "dirty" tuple, which is WRONG
                 * because that tuple slot has the wrong descriptor.)
                 */
                if (estate->es_junkFilter != NULL)
                        slot = ExecFilterJunk(estate->es_junkFilter, slot);

                /*
                 * If we are supposed to send the tuple somewhere, do so. (In
                 * practice, this is probably always the case at this point.)
                 */
                if (sendTuples)
                        (*dest->receiveSlot) (slot, dest);

                /*
                 * Count tuples processed, if this is a SELECT.  (For other operation
                 * types, the ModifyTable plan node must count the appropriate
                 * events.)
                 */
                if (operation == CMD_SELECT)
                        (estate->es_processed)++;

                /*
                 * check our tuple count.. if we've processed the proper number then
                 * quit, else loop again and process more tuples.  Zero numberTuples
                 * means no limit.
                 */
                current_tuple_count++;
                if (numberTuples && numberTuples == current_tuple_count)
                        break;
        }
}


/*
 * ExecRelCheck --- check that tuple meets constraints for result relation
 */
static const char *
ExecRelCheck(ResultRelInfo *resultRelInfo,
                         TupleTableSlot *slot, EState *estate)
{
        Relation        rel = resultRelInfo->ri_RelationDesc;
        int                     ncheck = rel->rd_att->constr->num_check;
        ConstrCheck *check = rel->rd_att->constr->check;
        ExprContext *econtext;
        MemoryContext oldContext;
        List       *qual;
        int                     i;

        /*
         * If first time through for this result relation, build expression
         * nodetrees for rel's constraint expressions.  Keep them in the per-query
         * memory context so they'll survive throughout the query.
         */
        if (resultRelInfo->ri_ConstraintExprs == NULL)
        {
                oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
                resultRelInfo->ri_ConstraintExprs =
                        (List **) palloc(ncheck * sizeof(List *));
                for (i = 0; i < ncheck; i++)
                {
                        /* ExecQual wants implicit-AND form */
                        qual = make_ands_implicit(stringToNode(check[i].ccbin));
                        resultRelInfo->ri_ConstraintExprs[i] = (List *)
                                ExecPrepareExpr((Expr *) qual, estate);
                }
                MemoryContextSwitchTo(oldContext);
        }

        /*
         * We will use the EState's per-tuple context for evaluating constraint
         * expressions (creating it if it's not already there).
         */
        econtext = GetPerTupleExprContext(estate);

        /* Arrange for econtext's scan tuple to be the tuple under test */
        econtext->ecxt_scantuple = slot;

        /* And evaluate the constraints */
        for (i = 0; i < ncheck; i++)
        {
                qual = resultRelInfo->ri_ConstraintExprs[i];

                /*
                 * NOTE: SQL92 specifies that a NULL result from a constraint
                 * expression is not to be treated as a failure.  Therefore, tell
                 * ExecQual to return TRUE for NULL.
                 */
                if (!ExecQual(qual, econtext, true))
                        return check[i].ccname;
        }

        /* NULL result means no error */
        return NULL;
}

void
ExecConstraints(ResultRelInfo *resultRelInfo,
                                TupleTableSlot *slot, EState *estate)
{
        Relation        rel = resultRelInfo->ri_RelationDesc;
        TupleConstr *constr = rel->rd_att->constr;

        Assert(constr);

        if (constr->has_not_null)
        {
                int                     natts = rel->rd_att->natts;
                int                     attrChk;

                for (attrChk = 1; attrChk <= natts; attrChk++)
                {
                        if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
                                slot_attisnull(slot, attrChk))
                                ereport(ERROR,
                                                (errcode(ERRCODE_NOT_NULL_VIOLATION),
                                                 errmsg("null value in column \"%s\" violates not-null constraint",
                                                NameStr(rel->rd_att->attrs[attrChk - 1]->attname)),
                                                 errdetail("Failing row contains %s.",
                                                                   ExecBuildSlotValueDescription(slot, 64))));
                }
        }

        if (constr->num_check > 0)
        {
                const char *failed;

                if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
                        ereport(ERROR,
                                        (errcode(ERRCODE_CHECK_VIOLATION),
                                         errmsg("new row for relation \"%s\" violates check constraint \"%s\"",
                                                        RelationGetRelationName(rel), failed),
                                         errdetail("Failing row contains %s.",
                                                           ExecBuildSlotValueDescription(slot, 64))));
        }
}

/*
 * ExecBuildSlotValueDescription -- construct a string representing a tuple
 *
 * This is intentionally very similar to BuildIndexValueDescription, but
 * unlike that function, we truncate long field values.  That seems necessary
 * here since heap field values could be very long, whereas index entries
 * typically aren't so wide.
 */
static char *
ExecBuildSlotValueDescription(TupleTableSlot *slot, int maxfieldlen)
{
        StringInfoData buf;
        TupleDesc       tupdesc = slot->tts_tupleDescriptor;
        int                     i;

        /* Make sure the tuple is fully deconstructed */
        slot_getallattrs(slot);

        initStringInfo(&buf);

        appendStringInfoChar(&buf, '(');

        for (i = 0; i < tupdesc->natts; i++)
        {
                char       *val;
                int                     vallen;

                if (slot->tts_isnull[i])
                        val = "null";
                else
                {
                        Oid                     foutoid;
                        bool            typisvarlena;

                        getTypeOutputInfo(tupdesc->attrs[i]->atttypid,
                                                          &foutoid, &typisvarlena);
                        val = OidOutputFunctionCall(foutoid, slot->tts_values[i]);
                }

                if (i > 0)
                        appendStringInfoString(&buf, ", ");

                /* truncate if needed */
                vallen = strlen(val);
                if (vallen <= maxfieldlen)
                        appendStringInfoString(&buf, val);
                else
                {
                        vallen = pg_mbcliplen(val, vallen, maxfieldlen);
                        appendBinaryStringInfo(&buf, val, vallen);
                        appendStringInfoString(&buf, "...");
                }
        }

        appendStringInfoChar(&buf, ')');

        return buf.data;
}


/*
 * ExecFindRowMark -- find the ExecRowMark struct for given rangetable index
 */
ExecRowMark *
ExecFindRowMark(EState *estate, Index rti)
{
        ListCell   *lc;

        foreach(lc, estate->es_rowMarks)
        {
                ExecRowMark *erm = (ExecRowMark *) lfirst(lc);

                if (erm->rti == rti)
                        return erm;
        }
        elog(ERROR, "failed to find ExecRowMark for rangetable index %u", rti);
        return NULL;                            /* keep compiler quiet */
}

/*
 * ExecBuildAuxRowMark -- create an ExecAuxRowMark struct
 *
 * Inputs are the underlying ExecRowMark struct and the targetlist of the
 * input plan node (not planstate node!).  We need the latter to find out
 * the column numbers of the resjunk columns.
 */
ExecAuxRowMark *
ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
{
        ExecAuxRowMark *aerm = (ExecAuxRowMark *) palloc0(sizeof(ExecAuxRowMark));
        char            resname[32];

        aerm->rowmark = erm;

        /* Look up the resjunk columns associated with this rowmark */
        if (erm->relation)
        {
                Assert(erm->markType != ROW_MARK_COPY);

                /* if child rel, need tableoid */
                if (erm->rti != erm->prti)
                {
                        snprintf(resname, sizeof(resname), "tableoid%u", erm->rowmarkId);
                        aerm->toidAttNo = ExecFindJunkAttributeInTlist(targetlist,
                                                                                                                   resname);
                        if (!AttributeNumberIsValid(aerm->toidAttNo))
                                elog(ERROR, "could not find junk %s column", resname);
                }

                /* always need ctid for real relations */
                snprintf(resname, sizeof(resname), "ctid%u", erm->rowmarkId);
                aerm->ctidAttNo = ExecFindJunkAttributeInTlist(targetlist,
                                                                                                           resname);
                if (!AttributeNumberIsValid(aerm->ctidAttNo))
                        elog(ERROR, "could not find junk %s column", resname);
        }
        else
        {
                Assert(erm->markType == ROW_MARK_COPY);

                snprintf(resname, sizeof(resname), "wholerow%u", erm->rowmarkId);
                aerm->wholeAttNo = ExecFindJunkAttributeInTlist(targetlist,
                                                                                                                resname);
                if (!AttributeNumberIsValid(aerm->wholeAttNo))
                        elog(ERROR, "could not find junk %s column", resname);
        }

        return aerm;
}


/*
 * EvalPlanQual logic --- recheck modified tuple(s) to see if we want to
 * process the updated version under READ COMMITTED rules.
 *
 * See backend/executor/README for some info about how this works.
 */


/*
 * Check a modified tuple to see if we want to process its updated version
 * under READ COMMITTED rules.
 *
 *      estate - outer executor state data
 *      epqstate - state for EvalPlanQual rechecking
 *      relation - table containing tuple
 *      rti - rangetable index of table containing tuple
 *      *tid - t_ctid from the outdated tuple (ie, next updated version)
 *      priorXmax - t_xmax from the outdated tuple
 *
 * *tid is also an output parameter: it's modified to hold the TID of the
 * latest version of the tuple (note this may be changed even on failure)
 *
 * Returns a slot containing the new candidate update/delete tuple, or
 * NULL if we determine we shouldn't process the row.
 */
TupleTableSlot *
EvalPlanQual(EState *estate, EPQState *epqstate,
                         Relation relation, Index rti,
                         ItemPointer tid, TransactionId priorXmax)
{
        TupleTableSlot *slot;
        HeapTuple       copyTuple;

        Assert(rti > 0);

        /*
         * Get and lock the updated version of the row; if fail, return NULL.
         */
        copyTuple = EvalPlanQualFetch(estate, relation, LockTupleExclusive,
                                                                  tid, priorXmax);

        if (copyTuple == NULL)
                return NULL;

        /*
         * For UPDATE/DELETE we have to return tid of actual row we're executing
         * PQ for.
         */
        *tid = copyTuple->t_self;

        /*
         * Need to run a recheck subquery.      Initialize or reinitialize EPQ state.
         */
        EvalPlanQualBegin(epqstate, estate);

        /*
         * Free old test tuple, if any, and store new tuple where relation's scan
         * node will see it
         */
        EvalPlanQualSetTuple(epqstate, rti, copyTuple);

        /*
         * Fetch any non-locked source rows
         */
        EvalPlanQualFetchRowMarks(epqstate);

        /*
         * Run the EPQ query.  We assume it will return at most one tuple.
         */
        slot = EvalPlanQualNext(epqstate);

        /*
         * If we got a tuple, force the slot to materialize the tuple so that it
         * is not dependent on any local state in the EPQ query (in particular,
         * it's highly likely that the slot contains references to any pass-by-ref
         * datums that may be present in copyTuple).  As with the next step, this
         * is to guard against early re-use of the EPQ query.
         */
        if (!TupIsNull(slot))
                (void) ExecMaterializeSlot(slot);

        /*
         * Clear out the test tuple.  This is needed in case the EPQ query is
         * re-used to test a tuple for a different relation.  (Not clear that can
         * really happen, but let's be safe.)
         */
        EvalPlanQualSetTuple(epqstate, rti, NULL);

        return slot;
}

/*
 * Fetch a copy of the newest version of an outdated tuple
 *
 *      estate - executor state data
 *      relation - table containing tuple
 *      lockmode - requested tuple lock mode
 *      *tid - t_ctid from the outdated tuple (ie, next updated version)
 *      priorXmax - t_xmax from the outdated tuple
 *
 * Returns a palloc'd copy of the newest tuple version, or NULL if we find
 * that there is no newest version (ie, the row was deleted not updated).
 * If successful, we have locked the newest tuple version, so caller does not
 * need to worry about it changing anymore.
 *
 * Note: properly, lockmode should be declared as enum LockTupleMode,
 * but we use "int" to avoid having to include heapam.h in executor.h.
 */
HeapTuple
EvalPlanQualFetch(EState *estate, Relation relation, int lockmode,
                                  ItemPointer tid, TransactionId priorXmax)
{
        HeapTuple       copyTuple = NULL;
        HeapTupleData tuple;
        SnapshotData SnapshotDirty;

        /*
         * fetch target tuple
         *
         * Loop here to deal with updated or busy tuples
         */
        InitDirtySnapshot(SnapshotDirty);
        tuple.t_self = *tid;
        for (;;)
        {
                Buffer          buffer;

                if (heap_fetch(relation, &SnapshotDirty, &tuple, &buffer, true, NULL))
                {
                        HTSU_Result test;
                        ItemPointerData update_ctid;
                        TransactionId update_xmax;

                        /*
                         * If xmin isn't what we're expecting, the slot must have been
                         * recycled and reused for an unrelated tuple.  This implies that
                         * the latest version of the row was deleted, so we need do
                         * nothing.  (Should be safe to examine xmin without getting
                         * buffer's content lock, since xmin never changes in an existing
                         * tuple.)
                         */
                        if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple.t_data),
                                                                         priorXmax))
                        {
                                ReleaseBuffer(buffer);
                                return NULL;
                        }

                        /* otherwise xmin should not be dirty... */
                        if (TransactionIdIsValid(SnapshotDirty.xmin))
                                elog(ERROR, "t_xmin is uncommitted in tuple to be updated");

                        /*
                         * If tuple is being updated by other transaction then we have to
                         * wait for its commit/abort.
                         */
                        if (TransactionIdIsValid(SnapshotDirty.xmax))
                        {
                                ReleaseBuffer(buffer);
                                XactLockTableWait(SnapshotDirty.xmax);
                                continue;               /* loop back to repeat heap_fetch */
                        }

                        /*
                         * If tuple was inserted by our own transaction, we have to check
                         * cmin against es_output_cid: cmin >= current CID means our
                         * command cannot see the tuple, so we should ignore it.  Without
                         * this we are open to the "Halloween problem" of indefinitely
                         * re-updating the same tuple. (We need not check cmax because
                         * HeapTupleSatisfiesDirty will consider a tuple deleted by our
                         * transaction dead, regardless of cmax.)  We just checked that
                         * priorXmax == xmin, so we can test that variable instead of
                         * doing HeapTupleHeaderGetXmin again.
                         */
                        if (TransactionIdIsCurrentTransactionId(priorXmax) &&
                                HeapTupleHeaderGetCmin(tuple.t_data) >= estate->es_output_cid)
                        {
                                ReleaseBuffer(buffer);
                                return NULL;
                        }

                        /*
                         * This is a live tuple, so now try to lock it.
                         */
                        test = heap_lock_tuple(relation, &tuple, &buffer,
                                                                   &update_ctid, &update_xmax,
                                                                   estate->es_output_cid,
                                                                   lockmode, false);
                        /* We now have two pins on the buffer, get rid of one */
                        ReleaseBuffer(buffer);

                        switch (test)
                        {
                                case HeapTupleSelfUpdated:
                                        /* treat it as deleted; do not process */
                                        ReleaseBuffer(buffer);
                                        return NULL;

                                case HeapTupleMayBeUpdated:
                                        /* successfully locked */
                                        break;

                                case HeapTupleUpdated:
                                        ReleaseBuffer(buffer);
                                        if (IsolationUsesXactSnapshot())
                                                ereport(ERROR,
                                                                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                                                                 errmsg("could not serialize access due to concurrent update")));
                                        if (!ItemPointerEquals(&update_ctid, &tuple.t_self))
                                        {
                                                /* it was updated, so look at the updated version */
                                                tuple.t_self = update_ctid;
                                                /* updated row should have xmin matching this xmax */
                                                priorXmax = update_xmax;
                                                continue;
                                        }
                                        /* tuple was deleted, so give up */
                                        return NULL;

                                default:
                                        ReleaseBuffer(buffer);
                                        elog(ERROR, "unrecognized heap_lock_tuple status: %u",
                                                 test);
                                        return NULL;    /* keep compiler quiet */
                        }

                        /*
                         * We got tuple - now copy it for use by recheck query.
                         */
                        copyTuple = heap_copytuple(&tuple);
                        ReleaseBuffer(buffer);
                        break;
                }

                /*
                 * If the referenced slot was actually empty, the latest version of
                 * the row must have been deleted, so we need do nothing.
                 */
                if (tuple.t_data == NULL)
                {
                        ReleaseBuffer(buffer);
                        return NULL;
                }

                /*
                 * As above, if xmin isn't what we're expecting, do nothing.
                 */
                if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple.t_data),
                                                                 priorXmax))
                {
                        ReleaseBuffer(buffer);
                        return NULL;
                }

                /*
                 * If we get here, the tuple was found but failed SnapshotDirty.
                 * Assuming the xmin is either a committed xact or our own xact (as it
                 * certainly should be if we're trying to modify the tuple), this must
                 * mean that the row was updated or deleted by either a committed xact
                 * or our own xact.  If it was deleted, we can ignore it; if it was
                 * updated then chain up to the next version and repeat the whole
                 * process.
                 *
                 * As above, it should be safe to examine xmax and t_ctid without the
                 * buffer content lock, because they can't be changing.
                 */
                if (ItemPointerEquals(&tuple.t_self, &tuple.t_data->t_ctid))
                {
                        /* deleted, so forget about it */
                        ReleaseBuffer(buffer);
                        return NULL;
                }

                /* updated, so look at the updated row */
                tuple.t_self = tuple.t_data->t_ctid;
                /* updated row should have xmin matching this xmax */
                priorXmax = HeapTupleHeaderGetXmax(tuple.t_data);
                ReleaseBuffer(buffer);
                /* loop back to fetch next in chain */
        }

        /*
         * Return the copied tuple
         */
        return copyTuple;
}

/*
 * EvalPlanQualInit -- initialize during creation of a plan state node
 * that might need to invoke EPQ processing.
 *
 * Note: subplan/auxrowmarks can be NULL/NIL if they will be set later
 * with EvalPlanQualSetPlan.
 */
void
EvalPlanQualInit(EPQState *epqstate, EState *estate,
                                 Plan *subplan, List *auxrowmarks, int epqParam)
{
        /* Mark the EPQ state inactive */
        epqstate->estate = NULL;
        epqstate->planstate = NULL;
        epqstate->origslot = NULL;
        /* ... and remember data that EvalPlanQualBegin will need */
        epqstate->plan = subplan;
        epqstate->arowMarks = auxrowmarks;
        epqstate->epqParam = epqParam;
}

/*
 * EvalPlanQualSetPlan -- set or change subplan of an EPQState.
 *
 * We need this so that ModifyTuple can deal with multiple subplans.
 */
void
EvalPlanQualSetPlan(EPQState *epqstate, Plan *subplan, List *auxrowmarks)
{
        /* If we have a live EPQ query, shut it down */
        EvalPlanQualEnd(epqstate);
        /* And set/change the plan pointer */
        epqstate->plan = subplan;
        /* The rowmarks depend on the plan, too */
        epqstate->arowMarks = auxrowmarks;
}

/*
 * Install one test tuple into EPQ state, or clear test tuple if tuple == NULL
 *
 * NB: passed tuple must be palloc'd; it may get freed later
 */
void
EvalPlanQualSetTuple(EPQState *epqstate, Index rti, HeapTuple tuple)
{
        EState     *estate = epqstate->estate;

        Assert(rti > 0);

        /*
         * free old test tuple, if any, and store new tuple where relation's scan
         * node will see it
         */
        if (estate->es_epqTuple[rti - 1] != NULL)
                heap_freetuple(estate->es_epqTuple[rti - 1]);
        estate->es_epqTuple[rti - 1] = tuple;
        estate->es_epqTupleSet[rti - 1] = true;
}

/*
 * Fetch back the current test tuple (if any) for the specified RTI
 */
HeapTuple
EvalPlanQualGetTuple(EPQState *epqstate, Index rti)
{
        EState     *estate = epqstate->estate;

        Assert(rti > 0);

        return estate->es_epqTuple[rti - 1];
}

/*
 * Fetch the current row values for any non-locked relations that need
 * to be scanned by an EvalPlanQual operation.  origslot must have been set
 * to contain the current result row (top-level row) that we need to recheck.
 */
void
EvalPlanQualFetchRowMarks(EPQState *epqstate)
{
        ListCell   *l;

        Assert(epqstate->origslot != NULL);

        foreach(l, epqstate->arowMarks)
        {
                ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(l);
                ExecRowMark *erm = aerm->rowmark;
                Datum           datum;
                bool            isNull;
                HeapTupleData tuple;

                if (RowMarkRequiresRowShareLock(erm->markType))
                        elog(ERROR, "EvalPlanQual doesn't support locking rowmarks");

                /* clear any leftover test tuple for this rel */
                EvalPlanQualSetTuple(epqstate, erm->rti, NULL);

                if (erm->relation)
                {
                        Buffer          buffer;

                        Assert(erm->markType == ROW_MARK_REFERENCE);

                        /* if child rel, must check whether it produced this row */
                        if (erm->rti != erm->prti)
                        {
                                Oid                     tableoid;

                                datum = ExecGetJunkAttribute(epqstate->origslot,
                                                                                         aerm->toidAttNo,
                                                                                         &isNull);
                                /* non-locked rels could be on the inside of outer joins */
                                if (isNull)
                                        continue;
                                tableoid = DatumGetObjectId(datum);

                                if (tableoid != RelationGetRelid(erm->relation))
                                {
                                        /* this child is inactive right now */
                                        continue;
                                }
                        }

                        /* fetch the tuple's ctid */
                        datum = ExecGetJunkAttribute(epqstate->origslot,
                                                                                 aerm->ctidAttNo,
                                                                                 &isNull);
                        /* non-locked rels could be on the inside of outer joins */
                        if (isNull)
                                continue;
                        tuple.t_self = *((ItemPointer) DatumGetPointer(datum));

                        /* okay, fetch the tuple */
                        if (!heap_fetch(erm->relation, SnapshotAny, &tuple, &buffer,
                                                        false, NULL))
                                elog(ERROR, "failed to fetch tuple for EvalPlanQual recheck");

                        /* successful, copy and store tuple */
                        EvalPlanQualSetTuple(epqstate, erm->rti,
                                                                 heap_copytuple(&tuple));
                        ReleaseBuffer(buffer);
                }
                else
                {
                        HeapTupleHeader td;

                        Assert(erm->markType == ROW_MARK_COPY);

                        /* fetch the whole-row Var for the relation */
                        datum = ExecGetJunkAttribute(epqstate->origslot,
                                                                                 aerm->wholeAttNo,
                                                                                 &isNull);
                        /* non-locked rels could be on the inside of outer joins */
                        if (isNull)
                                continue;
                        td = DatumGetHeapTupleHeader(datum);

                        /* build a temporary HeapTuple control structure */
                        tuple.t_len = HeapTupleHeaderGetDatumLength(td);
                        ItemPointerSetInvalid(&(tuple.t_self));
                        tuple.t_tableOid = InvalidOid;
                        tuple.t_data = td;

                        /* copy and store tuple */
                        EvalPlanQualSetTuple(epqstate, erm->rti,
                                                                 heap_copytuple(&tuple));
                }
        }
}

/*
 * Fetch the next row (if any) from EvalPlanQual testing
 *
 * (In practice, there should never be more than one row...)
 */
TupleTableSlot *
EvalPlanQualNext(EPQState *epqstate)
{
        MemoryContext oldcontext;
        TupleTableSlot *slot;

        oldcontext = MemoryContextSwitchTo(epqstate->estate->es_query_cxt);
        slot = ExecProcNode(epqstate->planstate);
        MemoryContextSwitchTo(oldcontext);

        return slot;
}

/*
 * Initialize or reset an EvalPlanQual state tree
 */
void
EvalPlanQualBegin(EPQState *epqstate, EState *parentestate)
{
        EState     *estate = epqstate->estate;

        if (estate == NULL)
        {
                /* First time through, so create a child EState */
                EvalPlanQualStart(epqstate, parentestate, epqstate->plan);
        }
        else
        {
                /*
                 * We already have a suitable child EPQ tree, so just reset it.
                 */
                int                     rtsize = list_length(parentestate->es_range_table);
                PlanState  *planstate = epqstate->planstate;

                MemSet(estate->es_epqScanDone, 0, rtsize * sizeof(bool));

                /* Recopy current values of parent parameters */
                if (parentestate->es_plannedstmt->nParamExec > 0)
                {
                        int                     i = parentestate->es_plannedstmt->nParamExec;

                        while (--i >= 0)
                        {
                                /* copy value if any, but not execPlan link */
                                estate->es_param_exec_vals[i].value =
                                        parentestate->es_param_exec_vals[i].value;
                                estate->es_param_exec_vals[i].isnull =
                                        parentestate->es_param_exec_vals[i].isnull;
                        }
                }

                /*
                 * Mark child plan tree as needing rescan at all scan nodes.  The
                 * first ExecProcNode will take care of actually doing the rescan.
                 */
                planstate->chgParam = bms_add_member(planstate->chgParam,
                                                                                         epqstate->epqParam);
        }
}

/*
 * Start execution of an EvalPlanQual plan tree.
 *
 * This is a cut-down version of ExecutorStart(): we copy some state from
 * the top-level estate rather than initializing it fresh.
 */
static void
EvalPlanQualStart(EPQState *epqstate, EState *parentestate, Plan *planTree)
{
        EState     *estate;
        int                     rtsize;
        MemoryContext oldcontext;
        ListCell   *l;

        rtsize = list_length(parentestate->es_range_table);

        epqstate->estate = estate = CreateExecutorState();

        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        /*
         * Child EPQ EStates share the parent's copy of unchanging state such as
         * the snapshot, rangetable, result-rel info, and external Param info.
         * They need their own copies of local state, including a tuple table,
         * es_param_exec_vals, etc.
         */
        estate->es_direction = ForwardScanDirection;
        estate->es_snapshot = parentestate->es_snapshot;
        estate->es_crosscheck_snapshot = parentestate->es_crosscheck_snapshot;
        estate->es_range_table = parentestate->es_range_table;
        estate->es_plannedstmt = parentestate->es_plannedstmt;
        estate->es_junkFilter = parentestate->es_junkFilter;
        estate->es_output_cid = parentestate->es_output_cid;
        estate->es_result_relations = parentestate->es_result_relations;
        estate->es_num_result_relations = parentestate->es_num_result_relations;
        estate->es_result_relation_info = parentestate->es_result_relation_info;
        /* es_trig_target_relations must NOT be copied */
        estate->es_rowMarks = parentestate->es_rowMarks;
        estate->es_top_eflags = parentestate->es_top_eflags;
        estate->es_instrument = parentestate->es_instrument;
        estate->es_select_into = parentestate->es_select_into;
        estate->es_into_oids = parentestate->es_into_oids;
        /* es_auxmodifytables must NOT be copied */

        /*
         * The external param list is simply shared from parent.  The internal
         * param workspace has to be local state, but we copy the initial values
         * from the parent, so as to have access to any param values that were
         * already set from other parts of the parent's plan tree.
         */
        estate->es_param_list_info = parentestate->es_param_list_info;
        if (parentestate->es_plannedstmt->nParamExec > 0)
        {
                int                     i = parentestate->es_plannedstmt->nParamExec;

                estate->es_param_exec_vals = (ParamExecData *)
                        palloc0(i * sizeof(ParamExecData));
                while (--i >= 0)
                {
                        /* copy value if any, but not execPlan link */
                        estate->es_param_exec_vals[i].value =
                                parentestate->es_param_exec_vals[i].value;
                        estate->es_param_exec_vals[i].isnull =
                                parentestate->es_param_exec_vals[i].isnull;
                }
        }

        /*
         * Each EState must have its own es_epqScanDone state, but if we have
         * nested EPQ checks they should share es_epqTuple arrays.      This allows
         * sub-rechecks to inherit the values being examined by an outer recheck.
         */
        estate->es_epqScanDone = (bool *) palloc0(rtsize * sizeof(bool));
        if (parentestate->es_epqTuple != NULL)
        {
                estate->es_epqTuple = parentestate->es_epqTuple;
                estate->es_epqTupleSet = parentestate->es_epqTupleSet;
        }
        else
        {
                estate->es_epqTuple = (HeapTuple *)
                        palloc0(rtsize * sizeof(HeapTuple));
                estate->es_epqTupleSet = (bool *)
                        palloc0(rtsize * sizeof(bool));
        }

        /*
         * Each estate also has its own tuple table.
         */
        estate->es_tupleTable = NIL;

        /*
         * Initialize private state information for each SubPlan.  We must do this
         * before running ExecInitNode on the main query tree, since
         * ExecInitSubPlan expects to be able to find these entries. Some of the
         * SubPlans might not be used in the part of the plan tree we intend to
         * run, but since it's not easy to tell which, we just initialize them
         * all.  (However, if the subplan is headed by a ModifyTable node, then it
         * must be a data-modifying CTE, which we will certainly not need to
         * re-run, so we can skip initializing it.      This is just an efficiency
         * hack; it won't skip data-modifying CTEs for which the ModifyTable node
         * is not at the top.)
         */
        Assert(estate->es_subplanstates == NIL);
        foreach(l, parentestate->es_plannedstmt->subplans)
        {
                Plan       *subplan = (Plan *) lfirst(l);
                PlanState  *subplanstate;

                /* Don't initialize ModifyTable subplans, per comment above */
                if (IsA(subplan, ModifyTable))
                        subplanstate = NULL;
                else
                        subplanstate = ExecInitNode(subplan, estate, 0);

                estate->es_subplanstates = lappend(estate->es_subplanstates,
                                                                                   subplanstate);
        }

        /*
         * Initialize the private state information for all the nodes in the part
         * of the plan tree we need to run.  This opens files, allocates storage
         * and leaves us ready to start processing tuples.
         */
        epqstate->planstate = ExecInitNode(planTree, estate, 0);

        MemoryContextSwitchTo(oldcontext);
}

/*
 * EvalPlanQualEnd -- shut down at termination of parent plan state node,
 * or if we are done with the current EPQ child.
 *
 * This is a cut-down version of ExecutorEnd(); basically we want to do most
 * of the normal cleanup, but *not* close result relations (which we are
 * just sharing from the outer query).  We do, however, have to close any
 * trigger target relations that got opened, since those are not shared.
 * (There probably shouldn't be any of the latter, but just in case...)
 */
void
EvalPlanQualEnd(EPQState *epqstate)
{
        EState     *estate = epqstate->estate;
        MemoryContext oldcontext;
        ListCell   *l;

        if (estate == NULL)
                return;                                 /* idle, so nothing to do */

        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        ExecEndNode(epqstate->planstate);

        foreach(l, estate->es_subplanstates)
        {
                PlanState  *subplanstate = (PlanState *) lfirst(l);

                ExecEndNode(subplanstate);
        }

        /* throw away the per-estate tuple table */
        ExecResetTupleTable(estate->es_tupleTable, false);

        /* close any trigger target relations attached to this EState */
        foreach(l, estate->es_trig_target_relations)
        {
                ResultRelInfo *resultRelInfo = (ResultRelInfo *) lfirst(l);

                /* Close indices and then the relation itself */
                ExecCloseIndices(resultRelInfo);
                heap_close(resultRelInfo->ri_RelationDesc, NoLock);
        }

        MemoryContextSwitchTo(oldcontext);

        FreeExecutorState(estate);

        /* Mark EPQState idle */
        epqstate->estate = NULL;
        epqstate->planstate = NULL;
        epqstate->origslot = NULL;
}


/*
 * Support for SELECT INTO (a/k/a CREATE TABLE AS)
 *
 * We implement SELECT INTO by diverting SELECT's normal output with
 * a specialized DestReceiver type.
 */

typedef struct
{
        DestReceiver pub;                       /* publicly-known function pointers */
        EState     *estate;                     /* EState we are working with */
        Relation        rel;                    /* Relation to write to */
        int                     hi_options;             /* heap_insert performance options */
        BulkInsertState bistate;        /* bulk insert state */
} DR_intorel;

/*
 * OpenIntoRel --- actually create the SELECT INTO target relation
 *
 * This also replaces QueryDesc->dest with the special DestReceiver for
 * SELECT INTO.  We assume that the correct result tuple type has already
 * been placed in queryDesc->tupDesc.
 */
static void
OpenIntoRel(QueryDesc *queryDesc)
{
        IntoClause *into = queryDesc->plannedstmt->intoClause;
        EState     *estate = queryDesc->estate;
        TupleDesc       intoTupDesc = queryDesc->tupDesc;
        Relation        intoRelationDesc;
        char       *intoName;
        Oid                     namespaceId;
        Oid                     tablespaceId;
        Datum           reloptions;
        Oid                     intoRelationId;
        DR_intorel *myState;
        RangeTblEntry  *rte;
        AttrNumber              attnum;
        static char *validnsps[] = HEAP_RELOPT_NAMESPACES;

        Assert(into);

        /*
         * XXX This code needs to be kept in sync with DefineRelation(). Maybe we
         * should try to use that function instead.
         */

        /*
         * Check consistency of arguments
         */
        if (into->onCommit != ONCOMMIT_NOOP
                && into->rel->relpersistence != RELPERSISTENCE_TEMP)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                                 errmsg("ON COMMIT can only be used on temporary tables")));

        {
                AclResult aclresult;
                int i;

                for (i = 0; i < intoTupDesc->natts; i++)
                {
                        Oid atttypid = intoTupDesc->attrs[i]->atttypid;

                        aclresult = pg_type_aclcheck(atttypid, GetUserId(), ACL_USAGE);
                        if (aclresult != ACLCHECK_OK)
                                aclcheck_error(aclresult, ACL_KIND_TYPE,
                                                           format_type_be(atttypid));
                }
        }

        /*
         * If a column name list was specified in CREATE TABLE AS, override the
         * column names derived from the query.  (Too few column names are OK, too
         * many are not.)  It would probably be all right to scribble directly on
         * the query's result tupdesc, but let's be safe and make a copy.
         */
        if (into->colNames)
        {
                ListCell   *lc;

                intoTupDesc = CreateTupleDescCopy(intoTupDesc);
                attnum = 1;
                foreach(lc, into->colNames)
                {
                        char       *colname = strVal(lfirst(lc));

                        if (attnum > intoTupDesc->natts)
                                ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("CREATE TABLE AS specifies too many column names")));
                        namestrcpy(&(intoTupDesc->attrs[attnum - 1]->attname), colname);
                        attnum++;
                }
        }

        /*
         * Find namespace to create in, check its permissions
         */
        intoName = into->rel->relname;
        namespaceId = RangeVarGetAndCheckCreationNamespace(into->rel);
        RangeVarAdjustRelationPersistence(into->rel, namespaceId);

        /*
         * Security check: disallow creating temp tables from security-restricted
         * code.  This is needed because calling code might not expect untrusted
         * tables to appear in pg_temp at the front of its search path.
         */
        if (into->rel->relpersistence == RELPERSISTENCE_TEMP
                && InSecurityRestrictedOperation())
                ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("cannot create temporary table within security-restricted operation")));

        /*
         * Select tablespace to use.  If not specified, use default tablespace
         * (which may in turn default to database's default).
         */
        if (into->tableSpaceName)
        {
                tablespaceId = get_tablespace_oid(into->tableSpaceName, false);
        }
        else
        {
                tablespaceId = GetDefaultTablespace(into->rel->relpersistence);
                /* note InvalidOid is OK in this case */
        }

        /* Check permissions except when using the database's default space */
        if (OidIsValid(tablespaceId) && tablespaceId != MyDatabaseTableSpace)
        {
                AclResult       aclresult;

                aclresult = pg_tablespace_aclcheck(tablespaceId, GetUserId(),
                                                                                   ACL_CREATE);

                if (aclresult != ACLCHECK_OK)
                        aclcheck_error(aclresult, ACL_KIND_TABLESPACE,
                                                   get_tablespace_name(tablespaceId));
        }

        /* Parse and validate any reloptions */
        reloptions = transformRelOptions((Datum) 0,
                                                                         into->options,
                                                                         NULL,
                                                                         validnsps,
                                                                         true,
                                                                         false);
        (void) heap_reloptions(RELKIND_RELATION, reloptions, true);

        /* Now we can actually create the new relation */
        intoRelationId = heap_create_with_catalog(intoName,
                                                                                          namespaceId,
                                                                                          tablespaceId,
                                                                                          InvalidOid,
                                                                                          InvalidOid,
                                                                                          InvalidOid,
                                                                                          GetUserId(),
                                                                                          intoTupDesc,
                                                                                          NIL,
                                                                                          RELKIND_RELATION,
                                                                                          into->rel->relpersistence,
                                                                                          false,
                                                                                          false,
                                                                                          true,
                                                                                          0,
                                                                                          into->onCommit,
                                                                                          reloptions,
                                                                                          true,
                                                                                          allowSystemTableMods);
        Assert(intoRelationId != InvalidOid);

        /*
         * Advance command counter so that the newly-created relation's catalog
         * tuples will be visible to heap_open.
         */
        CommandCounterIncrement();

        /*
         * If necessary, create a TOAST table for the INTO relation. Note that
         * AlterTableCreateToastTable ends with CommandCounterIncrement(), so that
         * the TOAST table will be visible for insertion.
         */
        reloptions = transformRelOptions((Datum) 0,
                                                                         into->options,
                                                                         "toast",
                                                                         validnsps,
                                                                         true,
                                                                         false);

        (void) heap_reloptions(RELKIND_TOASTVALUE, reloptions, true);

        AlterTableCreateToastTable(intoRelationId, reloptions);

        /*
         * And open the constructed table for writing.
         */
        intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock);

        /*
         * Check INSERT permission on the constructed table.
         */
        rte = makeNode(RangeTblEntry);
        rte->rtekind = RTE_RELATION;
        rte->relid = intoRelationId;
        rte->relkind = RELKIND_RELATION;
        rte->requiredPerms = ACL_INSERT;

        for (attnum = 1; attnum <= intoTupDesc->natts; attnum++)
                rte->modifiedCols = bms_add_member(rte->modifiedCols,
                                attnum - FirstLowInvalidHeapAttributeNumber);

        ExecCheckRTPerms(list_make1(rte), true);

        /*
         * Now replace the query's DestReceiver with one for SELECT INTO
         */
        queryDesc->dest = CreateDestReceiver(DestIntoRel);
        myState = (DR_intorel *) queryDesc->dest;
        Assert(myState->pub.mydest == DestIntoRel);
        myState->estate = estate;
        myState->rel = intoRelationDesc;

        /*
         * We can skip WAL-logging the insertions, unless PITR or streaming
         * replication is in use. We can skip the FSM in any case.
         */
        myState->hi_options = HEAP_INSERT_SKIP_FSM |
                (XLogIsNeeded() ? 0 : HEAP_INSERT_SKIP_WAL);
        myState->bistate = GetBulkInsertState();

        /* Not using WAL requires smgr_targblock be initially invalid */
        Assert(RelationGetTargetBlock(intoRelationDesc) == InvalidBlockNumber);
}

/*
 * CloseIntoRel --- clean up SELECT INTO at ExecutorEnd time
 */
static void
CloseIntoRel(QueryDesc *queryDesc)
{
        DR_intorel *myState = (DR_intorel *) queryDesc->dest;

        /* OpenIntoRel might never have gotten called */
        if (myState && myState->pub.mydest == DestIntoRel && myState->rel)
        {
                FreeBulkInsertState(myState->bistate);

                /* If we skipped using WAL, must heap_sync before commit */
                if (myState->hi_options & HEAP_INSERT_SKIP_WAL)
                        heap_sync(myState->rel);

                /* close rel, but keep lock until commit */
                heap_close(myState->rel, NoLock);

                myState->rel = NULL;
        }
}

/*
 * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
 */
DestReceiver *
CreateIntoRelDestReceiver(void)
{
        DR_intorel *self = (DR_intorel *) palloc0(sizeof(DR_intorel));

        self->pub.receiveSlot = intorel_receive;
        self->pub.rStartup = intorel_startup;
        self->pub.rShutdown = intorel_shutdown;
        self->pub.rDestroy = intorel_destroy;
        self->pub.mydest = DestIntoRel;

        /* private fields will be set by OpenIntoRel */

        return (DestReceiver *) self;
}

/*
 * intorel_startup --- executor startup
 */
static void
intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
{
        /* no-op */
}

/*
 * intorel_receive --- receive one tuple
 */
static void
intorel_receive(TupleTableSlot *slot, DestReceiver *self)
{
        DR_intorel *myState = (DR_intorel *) self;
        HeapTuple       tuple;

        /*
         * get the heap tuple out of the tuple table slot, making sure we have a
         * writable copy
         */
        tuple = ExecMaterializeSlot(slot);

        /*
         * force assignment of new OID (see comments in ExecInsert)
         */
        if (myState->rel->rd_rel->relhasoids)
                HeapTupleSetOid(tuple, InvalidOid);

        heap_insert(myState->rel,
                                tuple,
                                myState->estate->es_output_cid,
                                myState->hi_options,
                                myState->bistate);

        /* We know this is a newly created relation, so there are no indexes */
}

/*
 * intorel_shutdown --- executor end
 */
static void
intorel_shutdown(DestReceiver *self)
{
        /* no-op */
}

/*
 * intorel_destroy --- release DestReceiver object
 */
static void
intorel_destroy(DestReceiver *self)
{
        pfree(self);
}