execMain.c

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/*-------------------------------------------------------------------------
 *
 * 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) 1996-2017, 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/htup_details.h"
#include "access/sysattr.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "catalog/partition.h"
#include "catalog/pg_inherits_fn.h"
#include "catalog/pg_publication.h"
#include "commands/matview.h"
#include "commands/trigger.h"
#include "executor/execdebug.h"
#include "foreign/fdwapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteManip.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rls.h"
#include "utils/ruleutils.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,
            bool use_parallel_mode,
            CmdType operation,
            bool sendTuples,
            uint64 numberTuples,
            ScanDirection direction,
            DestReceiver *dest,
            bool execute_once);
static bool ExecCheckRTEPerms(RangeTblEntry *rte);
static bool ExecCheckRTEPermsModified(Oid relOid, Oid userid,
                          Bitmapset *modifiedCols,
                          AclMode requiredPerms);
static void ExecCheckXactReadOnly(PlannedStmt *plannedstmt);
static char *ExecBuildSlotValueDescription(Oid reloid,
                              TupleTableSlot *slot,
                              TupleDesc tupdesc,
                              Bitmapset *modifiedCols,
                              int maxfieldlen);
static char *ExecBuildSlotPartitionKeyDescription(Relation rel,
                                     Datum *values,
                                     bool *isnull,
                                     int maxfieldlen);
static void EvalPlanQualStart(EPQState *epqstate, EState *parentestate,
                  Plan *planTree);
static void ExecPartitionCheck(ResultRelInfo *resultRelInfo,
                   TupleTableSlot *slot, EState *estate);

/*
 * Note that GetUpdatedColumns() also exists in commands/trigger.c.  There does
 * not appear to be any good header to put it into, given the structures that
 * it uses, so we let them be duplicated.  Be sure to update both if one needs
 * to be changed, however.
 */
#define GetInsertedColumns(relinfo, estate) \
    (rt_fetch((relinfo)->ri_RangeTableIndex, (estate)->es_range_table)->insertedCols)
#define GetUpdatedColumns(relinfo, estate) \
    (rt_fetch((relinfo)->ri_RangeTableIndex, (estate)->es_range_table)->updatedCols)

/* 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.
     *
     * Don't allow writes in parallel mode.  Supporting UPDATE and DELETE
     * would require (a) storing the combocid hash in shared memory, rather
     * than synchronizing it just once at the start of parallelism, and (b) an
     * alternative to heap_update()'s reliance on xmax for mutual exclusion.
     * INSERT may have no such troubles, but we forbid it to simplify the
     * checks.
     *
     * We have lower-level defenses in CommandCounterIncrement and elsewhere
     * against performing unsafe operations in parallel mode, but this gives a
     * more user-friendly error message.
     */
    if ((XactReadOnly || IsInParallelMode()) &&
        !(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));

    estate->es_sourceText = queryDesc->sourceText;

    /*
     * Fill in the query environment, if any, from queryDesc.
     */
    estate->es_queryEnv = queryDesc->queryEnv;

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

            /*
             * SELECT FOR [KEY] UPDATE/SHARE and modifying CTEs need to mark
             * tuples
             */
            if (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.  Also note that the count limit is only applied to
 *      retrieved tuples, not for instance to those inserted/updated/deleted
 *      by a ModifyTable plan node.
 *
 *      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, uint64 count,
            bool execute_once)
{
    if (ExecutorRun_hook)
        (*ExecutorRun_hook) (queryDesc, direction, count, execute_once);
    else
        standard_ExecutorRun(queryDesc, direction, count, execute_once);
}

void
standard_ExecutorRun(QueryDesc *queryDesc,
                     ScanDirection direction, uint64 count, bool execute_once)
{
    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);

    /*
     * run plan
     */
    if (!ScanDirectionIsNoMovement(direction))
    {
        if (execute_once && queryDesc->already_executed)
            elog(ERROR, "can't re-execute query flagged for single execution");
        queryDesc->already_executed = true;

        ExecutePlan(estate,
                    queryDesc->planstate,
                    queryDesc->plannedstmt->parallelModeNeeded,
                    operation,
                    sendTuples,
                    count,
                    direction,
                    dest,
                    execute_once);
    }

    /*
     * 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);

    /* 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.
 *
 * Note that this does NOT address row level security policies (aka: RLS).  If
 * rows will be returned to the user as a result of this permission check
 * passing, then RLS also needs to be consulted (and check_enable_rls()).
 *
 * See rewrite/rowsecurity.c.
 */
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;

    /*
     * Only plain-relation RTEs need to be checked here.  Function RTEs are
     * checked 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)
    {
        int         col = -1;

        /*
         * 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;
            }

            while ((col = bms_next_member(rte->selectedCols, col)) >= 0)
            {
                /* bit #s are offset by FirstLowInvalidHeapAttributeNumber */
                AttrNumber  attno = col + FirstLowInvalidHeapAttributeNumber;

                if (attno == 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, attno, userid,
                                              ACL_SELECT) != ACLCHECK_OK)
                        return false;
                }
            }
        }

        /*
         * Basically the same for the mod columns, for both INSERT and UPDATE
         * privilege as specified by remainingPerms.
         */
        if (remainingPerms & ACL_INSERT && !ExecCheckRTEPermsModified(relOid,
                                                                      userid,
                                                                      rte->insertedCols,
                                                                      ACL_INSERT))
            return false;

        if (remainingPerms & ACL_UPDATE && !ExecCheckRTEPermsModified(relOid,
                                                                      userid,
                                                                      rte->updatedCols,
                                                                      ACL_UPDATE))
            return false;
    }
    return true;
}

/*
 * ExecCheckRTEPermsModified
 *      Check INSERT or UPDATE access permissions for a single RTE (these
 *      are processed uniformly).
 */
static bool
ExecCheckRTEPermsModified(Oid relOid, Oid userid, Bitmapset *modifiedCols,
                          AclMode requiredPerms)
{
    int         col = -1;

    /*
     * When the query doesn't explicitly update 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 UPDATE.
     */
    if (bms_is_empty(modifiedCols))
    {
        if (pg_attribute_aclcheck_all(relOid, userid, requiredPerms,
                                      ACLMASK_ANY) != ACLCHECK_OK)
            return false;
    }

    while ((col = bms_next_member(modifiedCols, col)) >= 0)
    {
        /* bit #s are offset by FirstLowInvalidHeapAttributeNumber */
        AttrNumber  attno = col + FirstLowInvalidHeapAttributeNumber;

        if (attno == InvalidAttrNumber)
        {
            /* whole-row reference can't happen here */
            elog(ERROR, "whole-row update is not implemented");
        }
        else
        {
            if (pg_attribute_aclcheck(relOid, attno, userid,
                                      requiredPerms) != ACLCHECK_OK)
                return false;
        }
    }
    return true;
}

/*
 * Check that the query does not imply any writes to non-temp tables;
 * unless we're in parallel mode, in which case don't even allow writes
 * to temp tables.
 *
 * Note: in a Hot Standby this would need to reject writes to temp
 * tables just as we do in parallel mode; but an HS standby can't have created
 * any temp tables in the first place, so no need to check that.
 */
static void
ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
{
    ListCell   *l;

    /*
     * Fail if write permissions are requested in parallel mode for table
     * (temp or non-temp), otherwise fail for 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));
    }

    if (plannedstmt->commandType != CMD_SELECT || plannedstmt->hasModifyingCTE)
        PreventCommandIfParallelMode(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,
                              NULL,
                              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;

        /*
         * In the partitioned result relation case, lock the non-leaf result
         * relations too.  A subset of these are the roots of respective
         * partitioned tables, for which we also allocate ResulRelInfos.
         */
        estate->es_root_result_relations = NULL;
        estate->es_num_root_result_relations = 0;
        if (plannedstmt->nonleafResultRelations)
        {
            int         num_roots = list_length(plannedstmt->rootResultRelations);

            /*
             * Firstly, build ResultRelInfos for all the partitioned table
             * roots, because we will need them to fire the statement-level
             * triggers, if any.
             */
            resultRelInfos = (ResultRelInfo *)
                palloc(num_roots * sizeof(ResultRelInfo));
            resultRelInfo = resultRelInfos;
            foreach(l, plannedstmt->rootResultRelations)
            {
                Index       resultRelIndex = lfirst_int(l);
                Oid         resultRelOid;
                Relation    resultRelDesc;

                resultRelOid = getrelid(resultRelIndex, rangeTable);
                resultRelDesc = heap_open(resultRelOid, RowExclusiveLock);
                InitResultRelInfo(resultRelInfo,
                                  resultRelDesc,
                                  lfirst_int(l),
                                  NULL,
                                  estate->es_instrument);
                resultRelInfo++;
            }

            estate->es_root_result_relations = resultRelInfos;
            estate->es_num_root_result_relations = num_roots;

            /* Simply lock the rest of them. */
            foreach(l, plannedstmt->nonleafResultRelations)
            {
                Index       resultRelIndex = lfirst_int(l);

                /* We locked the roots above. */
                if (!list_member_int(plannedstmt->rootResultRelations,
                                     resultRelIndex))
                    LockRelationOid(getrelid(resultRelIndex, rangeTable),
                                    RowExclusiveLock);
            }
        }
    }
    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;
        estate->es_root_result_relations = NULL;
        estate->es_num_root_result_relations = 0;
    }

    /*
     * Similarly, we have to lock relations selected FOR [KEY] UPDATE/SHARE
     * before we initialize the plan tree, else we'd be risking lock upgrades.
     * While we are at it, build the ExecRowMark list.  Any partitioned child
     * tables are ignored here (because isParent=true) and will be locked by
     * the first Append or MergeAppend node that references them.  (Note that
     * the RowMarks corresponding to partitioned child tables are present in
     * the same list as the rest, i.e., plannedstmt->rowMarks.)
     */
    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;

        /* get relation's OID (will produce InvalidOid if subquery) */
        relid = getrelid(rc->rti, rangeTable);

        /*
         * If you change the conditions under which rel locks are acquired
         * here, be sure to adjust ExecOpenScanRelation to match.
         */
        switch (rc->markType)
        {
            case ROW_MARK_EXCLUSIVE:
            case ROW_MARK_NOKEYEXCLUSIVE:
            case ROW_MARK_SHARE:
            case ROW_MARK_KEYSHARE:
                relation = heap_open(relid, RowShareLock);
                break;
            case ROW_MARK_REFERENCE:
                relation = heap_open(relid, AccessShareLock);
                break;
            case ROW_MARK_COPY:
                /* no physical table access is required */
                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->relid = relid;
        erm->rti = rc->rti;
        erm->prti = rc->prti;
        erm->rowmarkId = rc->rowmarkId;
        erm->markType = rc->markType;
        erm->strength = rc->strength;
        erm->waitPolicy = rc->waitPolicy;
        erm->ermActive = false;
        ItemPointerSetInvalid(&(erm->curCtid));
        erm->ermExtra = NULL;
        estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
    }

    /*
     * 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 | EXEC_FLAG_WITH_NO_DATA);
        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.
     */
    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;
}

/*
 * Check that a proposed result relation is a legal target for the operation
 *
 * Generally the parser and/or planner should have noticed any such mistake
 * already, but let's make sure.
 *
 * Note: when changing this function, you probably also need to look at
 * CheckValidRowMarkRel.
 */
void
CheckValidResultRel(Relation resultRel, CmdType operation)
{
    TriggerDesc *trigDesc = resultRel->trigdesc;
    FdwRoutine *fdwroutine;

    switch (resultRel->rd_rel->relkind)
    {
        case RELKIND_RELATION:
        case RELKIND_PARTITIONED_TABLE:
            CheckCmdReplicaIdentity(resultRel, operation);
            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:

            /*
             * Okay only if there's a suitable INSTEAD OF trigger.  Messages
             * here should match rewriteHandler.c's rewriteTargetView, except
             * that we omit errdetail because we haven't got the information
             * handy (and given that we really shouldn't get here anyway, it's
             * not worth great exertion to get).
             */
            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("To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule.")));
                    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("To enable updating the view, provide an INSTEAD OF UPDATE trigger or an unconditional ON UPDATE DO INSTEAD rule.")));
                    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("To enable deleting from the view, provide an INSTEAD OF DELETE trigger or an unconditional ON DELETE DO INSTEAD rule.")));
                    break;
                default:
                    elog(ERROR, "unrecognized CmdType: %d", (int) operation);
                    break;
            }
            break;
        case RELKIND_MATVIEW:
            if (!MatViewIncrementalMaintenanceIsEnabled())
                ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("cannot change materialized view \"%s\"",
                                RelationGetRelationName(resultRel))));
            break;
        case RELKIND_FOREIGN_TABLE:
            /* Okay only if the FDW supports it */
            fdwroutine = GetFdwRoutineForRelation(resultRel, false);
            switch (operation)
            {
                case CMD_INSERT:
                    if (fdwroutine->ExecForeignInsert == NULL)
                        ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("cannot insert into foreign table \"%s\"",
                                        RelationGetRelationName(resultRel))));
                    if (fdwroutine->IsForeignRelUpdatable != NULL &&
                        (fdwroutine->IsForeignRelUpdatable(resultRel) & (1 << CMD_INSERT)) == 0)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("foreign table \"%s\" does not allow inserts",
                                        RelationGetRelationName(resultRel))));
                    break;
                case CMD_UPDATE:
                    if (fdwroutine->ExecForeignUpdate == NULL)
                        ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("cannot update foreign table \"%s\"",
                                        RelationGetRelationName(resultRel))));
                    if (fdwroutine->IsForeignRelUpdatable != NULL &&
                        (fdwroutine->IsForeignRelUpdatable(resultRel) & (1 << CMD_UPDATE)) == 0)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("foreign table \"%s\" does not allow updates",
                                        RelationGetRelationName(resultRel))));
                    break;
                case CMD_DELETE:
                    if (fdwroutine->ExecForeignDelete == NULL)
                        ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("cannot delete from foreign table \"%s\"",
                                        RelationGetRelationName(resultRel))));
                    if (fdwroutine->IsForeignRelUpdatable != NULL &&
                        (fdwroutine->IsForeignRelUpdatable(resultRel) & (1 << CMD_DELETE)) == 0)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("foreign table \"%s\" does not allow deletes",
                                        RelationGetRelationName(resultRel))));
                    break;
                default:
                    elog(ERROR, "unrecognized CmdType: %d", (int) operation);
                    break;
            }
            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)
{
    FdwRoutine *fdwroutine;

    switch (rel->rd_rel->relkind)
    {
        case RELKIND_RELATION:
        case RELKIND_PARTITIONED_TABLE:
            /* 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; planner should have expanded the view */
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot lock rows in view \"%s\"",
                            RelationGetRelationName(rel))));
            break;
        case RELKIND_MATVIEW:
            /* Allow referencing a matview, but not actual locking clauses */
            if (markType != ROW_MARK_REFERENCE)
                ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("cannot lock rows in materialized view \"%s\"",
                                RelationGetRelationName(rel))));
            break;
        case RELKIND_FOREIGN_TABLE:
            /* Okay only if the FDW supports it */
            fdwroutine = GetFdwRoutineForRelation(rel, false);
            if (fdwroutine->RefetchForeignRow == NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         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,
                  Relation partition_root,
                  int instrument_options)
{
    List       *partition_check = NIL;

    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 = (ExprState **)
            palloc0(n * sizeof(ExprState *));
        if (instrument_options)
            resultRelInfo->ri_TrigInstrument = InstrAlloc(n, instrument_options);
    }
    else
    {
        resultRelInfo->ri_TrigFunctions = NULL;
        resultRelInfo->ri_TrigWhenExprs = NULL;
        resultRelInfo->ri_TrigInstrument = NULL;
    }
    if (resultRelationDesc->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
        resultRelInfo->ri_FdwRoutine = GetFdwRoutineForRelation(resultRelationDesc, true);
    else
        resultRelInfo->ri_FdwRoutine = NULL;
    resultRelInfo->ri_FdwState = NULL;
    resultRelInfo->ri_usesFdwDirectModify = false;
    resultRelInfo->ri_ConstraintExprs = NULL;
    resultRelInfo->ri_junkFilter = NULL;
    resultRelInfo->ri_projectReturning = NULL;

    /*
     * Partition constraint, which also includes the partition constraint of
     * all the ancestors that are partitions.  Note that it will be checked
     * even in the case of tuple-routing where this table is the target leaf
     * partition, if there any BR triggers defined on the table.  Although
     * tuple-routing implicitly preserves the partition constraint of the
     * target partition for a given row, the BR triggers may change the row
     * such that the constraint is no longer satisfied, which we must fail for
     * by checking it explicitly.
     *
     * If this is a partitioned table, the partition constraint (if any) of a
     * given row will be checked just before performing tuple-routing.
     */
    partition_check = RelationGetPartitionQual(resultRelationDesc);

    resultRelInfo->ri_PartitionCheck = partition_check;
    resultRelInfo->ri_PartitionRoot = partition_root;
}

/*
 *      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, the
 * es_root_result_relations array (if any), or the es_leaf_result_relations
 * list (if any).  (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--;
    }
    /* Second, search through the root result relations, if any */
    rInfo = estate->es_root_result_relations;
    nr = estate->es_num_root_result_relations;
    while (nr > 0)
    {
        if (RelationGetRelid(rInfo->ri_RelationDesc) == relid)
            return rInfo;
        rInfo++;
        nr--;
    }
    /* Third, search through the leaf result relations, if any */
    foreach(l, estate->es_leaf_result_relations)
    {
        rInfo = (ResultRelInfo *) lfirst(l);
        if (RelationGetRelid(rInfo->ri_RelationDesc) == relid)
            return rInfo;
    }
    /* 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 */
                      NULL,
                      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;
}

/*
 * Close any relations that have been opened by ExecGetTriggerResultRel().
 */
void
ExecCleanUpTriggerState(EState *estate)
{
    ListCell   *l;

    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);
    }
}

/*
 *      ExecContextForcesOids
 *
 * This is pretty grotty: when doing INSERT, UPDATE, or CREATE TABLE AS,
 * 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.
 *
 * CREATE TABLE AS is even uglier, because we don't have the target relation's
 * descriptor available when this code runs; we have to look aside at the
 * flags passed to ExecutorStart().
 */
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_top_eflags & EXEC_FLAG_WITH_OIDS)
    {
        *hasoids = true;
        return true;
    }
    if (planstate->state->es_top_eflags & EXEC_FLAG_WITHOUT_OIDS)
    {
        *hasoids = false;
        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++;
    }

    /* Close the root target relation(s). */
    resultRelInfo = estate->es_root_result_relations;
    for (i = estate->es_num_root_result_relations; i > 0; i--)
    {
        heap_close(resultRelInfo->ri_RelationDesc, NoLock);
        resultRelInfo++;
    }

    /* likewise close any trigger target relations */
    ExecCleanUpTriggerState(estate);

    /*
     * close any relations selected FOR [KEY] UPDATE/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 retrieved '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,
            bool use_parallel_mode,
            CmdType operation,
            bool sendTuples,
            uint64 numberTuples,
            ScanDirection direction,
            DestReceiver *dest,
            bool execute_once)
{
    TupleTableSlot *slot;
    uint64      current_tuple_count;

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

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

    /*
     * If the plan might potentially be executed multiple times, we must force
     * it to run without parallelism, because we might exit early.  Also
     * disable parallelism when writing into a relation, because no database
     * changes are allowed in parallel mode.
     */
    if (!execute_once || dest->mydest == DestIntoRel)
        use_parallel_mode = false;

    if (use_parallel_mode)
        EnterParallelMode();

    /*
     * 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))
        {
            /* Allow nodes to release or shut down resources. */
            (void) ExecShutdownNode(planstate);
            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)
        {
            /*
             * If we are not able to send the tuple, we assume the destination
             * has closed and no more tuples can be sent. If that's the case,
             * end the loop.
             */
            if (!((*dest->receiveSlot) (slot, dest)))
                break;
        }

        /*
         * 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)
        {
            /* Allow nodes to release or shut down resources. */
            (void) ExecShutdownNode(planstate);
            break;
        }
    }

    if (use_parallel_mode)
        ExitParallelMode();
}


/*
 * ExecRelCheck --- check that tuple meets constraints for result relation
 *
 * Returns NULL if OK, else name of failed check constraint
 */
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;
    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 =
            (ExprState **) palloc(ncheck * sizeof(ExprState *));
        for (i = 0; i < ncheck; i++)
        {
            Expr       *checkconstr;

            checkconstr = stringToNode(check[i].ccbin);
            resultRelInfo->ri_ConstraintExprs[i] =
                ExecPrepareExpr(checkconstr, 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++)
    {
        ExprState  *checkconstr = resultRelInfo->ri_ConstraintExprs[i];

        /*
         * NOTE: SQL specifies that a NULL result from a constraint expression
         * is not to be treated as a failure.  Therefore, use ExecCheck not
         * ExecQual.
         */
        if (!ExecCheck(checkconstr, econtext))
            return check[i].ccname;
    }

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

/*
 * ExecPartitionCheck --- check that tuple meets the partition constraint.
 */
static void
ExecPartitionCheck(ResultRelInfo *resultRelInfo, TupleTableSlot *slot,
                   EState *estate)
{
    Relation    rel = resultRelInfo->ri_RelationDesc;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    Bitmapset  *modifiedCols;
    Bitmapset  *insertedCols;
    Bitmapset  *updatedCols;
    ExprContext *econtext;

    /*
     * If first time through, build expression state tree for the partition
     * check expression.  Keep it in the per-query memory context so they'll
     * survive throughout the query.
     */
    if (resultRelInfo->ri_PartitionCheckExpr == NULL)
    {
        List       *qual = resultRelInfo->ri_PartitionCheck;

        resultRelInfo->ri_PartitionCheckExpr = ExecPrepareCheck(qual, estate);
    }

    /*
     * 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;

    /*
     * As in case of the catalogued constraints, we treat a NULL result as
     * success here, not a failure.
     */
    if (!ExecCheck(resultRelInfo->ri_PartitionCheckExpr, econtext))
    {
        char       *val_desc;
        Relation    orig_rel = rel;

        /* See the comment above. */
        if (resultRelInfo->ri_PartitionRoot)
        {
            HeapTuple   tuple = ExecFetchSlotTuple(slot);
            TupleDesc   old_tupdesc = RelationGetDescr(rel);
            TupleConversionMap *map;

            rel = resultRelInfo->ri_PartitionRoot;
            tupdesc = RelationGetDescr(rel);
            /* a reverse map */
            map = convert_tuples_by_name(old_tupdesc, tupdesc,
                                         gettext_noop("could not convert row type"));
            if (map != NULL)
            {
                tuple = do_convert_tuple(tuple, map);
                ExecSetSlotDescriptor(slot, tupdesc);
                ExecStoreTuple(tuple, slot, InvalidBuffer, false);
            }
        }

        insertedCols = GetInsertedColumns(resultRelInfo, estate);
        updatedCols = GetUpdatedColumns(resultRelInfo, estate);
        modifiedCols = bms_union(insertedCols, updatedCols);
        val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
                                                 slot,
                                                 tupdesc,
                                                 modifiedCols,
                                                 64);
        ereport(ERROR,
                (errcode(ERRCODE_CHECK_VIOLATION),
                 errmsg("new row for relation \"%s\" violates partition constraint",
                        RelationGetRelationName(orig_rel)),
                 val_desc ? errdetail("Failing row contains %s.", val_desc) : 0));
    }
}

/*
 * ExecConstraints - check constraints of the tuple in 'slot'
 *
 * This checks the traditional NOT NULL and check constraints, as well as
 * the partition constraint, if any.
 *
 * Note: 'slot' contains the tuple to check the constraints of, which may
 * have been converted from the original input tuple after tuple routing.
 * 'resultRelInfo' is the original result relation, before tuple routing.
 */
void
ExecConstraints(ResultRelInfo *resultRelInfo,
                TupleTableSlot *slot, EState *estate)
{
    Relation    rel = resultRelInfo->ri_RelationDesc;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    TupleConstr *constr = tupdesc->constr;
    Bitmapset  *modifiedCols;
    Bitmapset  *insertedCols;
    Bitmapset  *updatedCols;

    Assert(constr || resultRelInfo->ri_PartitionCheck);

    if (constr && constr->has_not_null)
    {
        int         natts = tupdesc->natts;
        int         attrChk;

        for (attrChk = 1; attrChk <= natts; attrChk++)
        {
            Form_pg_attribute att = TupleDescAttr(tupdesc, attrChk - 1);

            if (att->attnotnull && slot_attisnull(slot, attrChk))
            {
                char       *val_desc;
                Relation    orig_rel = rel;
                TupleDesc   orig_tupdesc = RelationGetDescr(rel);

                /*
                 * If the tuple has been routed, it's been converted to the
                 * partition's rowtype, which might differ from the root
                 * table's.  We must convert it back to the root table's
                 * rowtype so that val_desc shown error message matches the
                 * input tuple.
                 */
                if (resultRelInfo->ri_PartitionRoot)
                {
                    HeapTuple   tuple = ExecFetchSlotTuple(slot);
                    TupleConversionMap *map;

                    rel = resultRelInfo->ri_PartitionRoot;
                    tupdesc = RelationGetDescr(rel);
                    /* a reverse map */
                    map = convert_tuples_by_name(orig_tupdesc, tupdesc,
                                                 gettext_noop("could not convert row type"));
                    if (map != NULL)
                    {
                        tuple = do_convert_tuple(tuple, map);
                        ExecSetSlotDescriptor(slot, tupdesc);
                        ExecStoreTuple(tuple, slot, InvalidBuffer, false);
                    }
                }

                insertedCols = GetInsertedColumns(resultRelInfo, estate);
                updatedCols = GetUpdatedColumns(resultRelInfo, estate);
                modifiedCols = bms_union(insertedCols, updatedCols);
                val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
                                                         slot,
                                                         tupdesc,
                                                         modifiedCols,
                                                         64);

                ereport(ERROR,
                        (errcode(ERRCODE_NOT_NULL_VIOLATION),
                         errmsg("null value in column \"%s\" violates not-null constraint",
                                NameStr(att->attname)),
                         val_desc ? errdetail("Failing row contains %s.", val_desc) : 0,
                         errtablecol(orig_rel, attrChk)));
            }
        }
    }

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

        if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
        {
            char       *val_desc;
            Relation    orig_rel = rel;

            /* See the comment above. */
            if (resultRelInfo->ri_PartitionRoot)
            {
                HeapTuple   tuple = ExecFetchSlotTuple(slot);
                TupleDesc   old_tupdesc = RelationGetDescr(rel);
                TupleConversionMap *map;

                rel = resultRelInfo->ri_PartitionRoot;
                tupdesc = RelationGetDescr(rel);
                /* a reverse map */
                map = convert_tuples_by_name(old_tupdesc, tupdesc,
                                             gettext_noop("could not convert row type"));
                if (map != NULL)
                {
                    tuple = do_convert_tuple(tuple, map);
                    ExecSetSlotDescriptor(slot, tupdesc);
                    ExecStoreTuple(tuple, slot, InvalidBuffer, false);
                }
            }

            insertedCols = GetInsertedColumns(resultRelInfo, estate);
            updatedCols = GetUpdatedColumns(resultRelInfo, estate);
            modifiedCols = bms_union(insertedCols, updatedCols);
            val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
                                                     slot,
                                                     tupdesc,
                                                     modifiedCols,
                                                     64);
            ereport(ERROR,
                    (errcode(ERRCODE_CHECK_VIOLATION),
                     errmsg("new row for relation \"%s\" violates check constraint \"%s\"",
                            RelationGetRelationName(orig_rel), failed),
                     val_desc ? errdetail("Failing row contains %s.", val_desc) : 0,
                     errtableconstraint(orig_rel, failed)));
        }
    }

    if (resultRelInfo->ri_PartitionCheck)
        ExecPartitionCheck(resultRelInfo, slot, estate);
}


/*
 * ExecWithCheckOptions -- check that tuple satisfies any WITH CHECK OPTIONs
 * of the specified kind.
 *
 * Note that this needs to be called multiple times to ensure that all kinds of
 * WITH CHECK OPTIONs are handled (both those from views which have the WITH
 * CHECK OPTION set and from row level security policies).  See ExecInsert()
 * and ExecUpdate().
 */
void
ExecWithCheckOptions(WCOKind kind, ResultRelInfo *resultRelInfo,
                     TupleTableSlot *slot, EState *estate)
{
    Relation    rel = resultRelInfo->ri_RelationDesc;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    ExprContext *econtext;
    ListCell   *l1,
               *l2;

    /*
     * 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;

    /* Check each of the constraints */
    forboth(l1, resultRelInfo->ri_WithCheckOptions,
            l2, resultRelInfo->ri_WithCheckOptionExprs)
    {
        WithCheckOption *wco = (WithCheckOption *) lfirst(l1);
        ExprState  *wcoExpr = (ExprState *) lfirst(l2);

        /*
         * Skip any WCOs which are not the kind we are looking for at this
         * time.
         */
        if (wco->kind != kind)
            continue;

        /*
         * WITH CHECK OPTION checks are intended to ensure that the new tuple
         * is visible (in the case of a view) or that it passes the
         * 'with-check' policy (in the case of row security). If the qual
         * evaluates to NULL or FALSE, then the new tuple won't be included in
         * the view or doesn't pass the 'with-check' policy for the table.
         */
        if (!ExecQual(wcoExpr, econtext))
        {
            char       *val_desc;
            Bitmapset  *modifiedCols;
            Bitmapset  *insertedCols;
            Bitmapset  *updatedCols;

            switch (wco->kind)
            {
                    /*
                     * For WITH CHECK OPTIONs coming from views, we might be
                     * able to provide the details on the row, depending on
                     * the permissions on the relation (that is, if the user
                     * could view it directly anyway).  For RLS violations, we
                     * don't include the data since we don't know if the user
                     * should be able to view the tuple as that depends on the
                     * USING policy.
                     */
                case WCO_VIEW_CHECK:
                    /* See the comment in ExecConstraints(). */
                    if (resultRelInfo->ri_PartitionRoot)
                    {
                        HeapTuple   tuple = ExecFetchSlotTuple(slot);
                        TupleDesc   old_tupdesc = RelationGetDescr(rel);
                        TupleConversionMap *map;

                        rel = resultRelInfo->ri_PartitionRoot;
                        tupdesc = RelationGetDescr(rel);
                        /* a reverse map */
                        map = convert_tuples_by_name(old_tupdesc, tupdesc,
                                                     gettext_noop("could not convert row type"));
                        if (map != NULL)
                        {
                            tuple = do_convert_tuple(tuple, map);
                            ExecSetSlotDescriptor(slot, tupdesc);
                            ExecStoreTuple(tuple, slot, InvalidBuffer, false);
                        }
                    }

                    insertedCols = GetInsertedColumns(resultRelInfo, estate);
                    updatedCols = GetUpdatedColumns(resultRelInfo, estate);
                    modifiedCols = bms_union(insertedCols, updatedCols);
                    val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
                                                             slot,
                                                             tupdesc,
                                                             modifiedCols,
                                                             64);

                    ereport(ERROR,
                            (errcode(ERRCODE_WITH_CHECK_OPTION_VIOLATION),
                             errmsg("new row violates check option for view \"%s\"",
                                    wco->relname),
                             val_desc ? errdetail("Failing row contains %s.",
                                                  val_desc) : 0));
                    break;
                case WCO_RLS_INSERT_CHECK:
                case WCO_RLS_UPDATE_CHECK:
                    if (wco->polname != NULL)
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("new row violates row-level security policy \"%s\" for table \"%s\"",
                                        wco->polname, wco->relname)));
                    else
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("new row violates row-level security policy for table \"%s\"",
                                        wco->relname)));
                    break;
                case WCO_RLS_CONFLICT_CHECK:
                    if (wco->polname != NULL)
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("new row violates row-level security policy \"%s\" (USING expression) for table \"%s\"",
                                        wco->polname, wco->relname)));
                    else
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("new row violates row-level security policy (USING expression) for table \"%s\"",
                                        wco->relname)));
                    break;
                default:
                    elog(ERROR, "unrecognized WCO kind: %u", wco->kind);
                    break;
            }
        }
    }
}

/*
 * ExecBuildSlotValueDescription -- construct a string representing a tuple
 *
 * This is intentionally very similar to BuildIndexValueDescription, but
 * unlike that function, we truncate long field values (to at most maxfieldlen
 * bytes).  That seems necessary here since heap field values could be very
 * long, whereas index entries typically aren't so wide.
 *
 * Also, unlike the case with index entries, we need to be prepared to ignore
 * dropped columns.  We used to use the slot's tuple descriptor to decode the
 * data, but the slot's descriptor doesn't identify dropped columns, so we
 * now need to be passed the relation's descriptor.
 *
 * Note that, like BuildIndexValueDescription, if the user does not have
 * permission to view any of the columns involved, a NULL is returned.  Unlike
 * BuildIndexValueDescription, if the user has access to view a subset of the
 * column involved, that subset will be returned with a key identifying which
 * columns they are.
 */
static char *
ExecBuildSlotValueDescription(Oid reloid,
                              TupleTableSlot *slot,
                              TupleDesc tupdesc,
                              Bitmapset *modifiedCols,
                              int maxfieldlen)
{
    StringInfoData buf;
    StringInfoData collist;
    bool        write_comma = false;
    bool        write_comma_collist = false;
    int         i;
    AclResult   aclresult;
    bool        table_perm = false;
    bool        any_perm = false;

    /*
     * Check if RLS is enabled and should be active for the relation; if so,
     * then don't return anything.  Otherwise, go through normal permission
     * checks.
     */
    if (check_enable_rls(reloid, InvalidOid, true) == RLS_ENABLED)
        return NULL;

    initStringInfo(&buf);

    appendStringInfoChar(&buf, '(');

    /*
     * Check if the user has permissions to see the row.  Table-level SELECT
     * allows access to all columns.  If the user does not have table-level
     * SELECT then we check each column and include those the user has SELECT
     * rights on.  Additionally, we always include columns the user provided
     * data for.
     */
    aclresult = pg_class_aclcheck(reloid, GetUserId(), ACL_SELECT);
    if (aclresult != ACLCHECK_OK)
    {
        /* Set up the buffer for the column list */
        initStringInfo(&collist);
        appendStringInfoChar(&collist, '(');
    }
    else
        table_perm = any_perm = true;

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

    for (i = 0; i < tupdesc->natts; i++)
    {
        bool        column_perm = false;
        char       *val;
        int         vallen;
        Form_pg_attribute att = TupleDescAttr(tupdesc, i);

        /* ignore dropped columns */
        if (att->attisdropped)
            continue;

        if (!table_perm)
        {
            /*
             * No table-level SELECT, so need to make sure they either have
             * SELECT rights on the column or that they have provided the data
             * for the column.  If not, omit this column from the error
             * message.
             */
            aclresult = pg_attribute_aclcheck(reloid, att->attnum,
                                              GetUserId(), ACL_SELECT);
            if (bms_is_member(att->attnum - FirstLowInvalidHeapAttributeNumber,
                              modifiedCols) || aclresult == ACLCHECK_OK)
            {
                column_perm = any_perm = true;

                if (write_comma_collist)
                    appendStringInfoString(&collist, ", ");
                else
                    write_comma_collist = true;

                appendStringInfoString(&collist, NameStr(att->attname));
            }
        }

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

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

            if (write_comma)
                appendStringInfoString(&buf, ", ");
            else
                write_comma = true;

            /* 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, "...");
            }
        }
    }

    /* If we end up with zero columns being returned, then return NULL. */
    if (!any_perm)
        return NULL;

    appendStringInfoChar(&buf, ')');

    if (!table_perm)
    {
        appendStringInfoString(&collist, ") = ");
        appendStringInfoString(&collist, buf.data);

        return collist.data;
    }

    return buf.data;
}


/*
 * ExecUpdateLockMode -- find the appropriate UPDATE tuple lock mode for a
 * given ResultRelInfo
 */
LockTupleMode
ExecUpdateLockMode(EState *estate, ResultRelInfo *relinfo)
{
    Bitmapset  *keyCols;
    Bitmapset  *updatedCols;

    /*
     * Compute lock mode to use.  If columns that are part of the key have not
     * been modified, then we can use a weaker lock, allowing for better
     * concurrency.
     */
    updatedCols = GetUpdatedColumns(relinfo, estate);
    keyCols = RelationGetIndexAttrBitmap(relinfo->ri_RelationDesc,
                                         INDEX_ATTR_BITMAP_KEY);

    if (bms_overlap(keyCols, updatedCols))
        return LockTupleExclusive;

    return LockTupleNoKeyExclusive;
}

/*
 * ExecFindRowMark -- find the ExecRowMark struct for given rangetable index
 *
 * If no such struct, either return NULL or throw error depending on missing_ok
 */
ExecRowMark *
ExecFindRowMark(EState *estate, Index rti, bool missing_ok)
{
    ListCell   *lc;

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

        if (erm->rti == rti)
            return erm;
    }
    if (!missing_ok)
        elog(ERROR, "failed to find ExecRowMark for rangetable index %u", rti);
    return NULL;
}

/*
 * 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->markType != ROW_MARK_COPY)
    {
        /* need ctid for all methods other than COPY */
        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
    {
        /* need wholerow if 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);
    }

    /* 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);
    }

    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
 *  lockmode - requested tuple lock mode
 *  *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.
 *
 * Note: properly, lockmode should be declared as enum LockTupleMode,
 * but we use "int" to avoid having to include heapam.h in executor.h.
 */
TupleTableSlot *
EvalPlanQual(EState *estate, EPQState *epqstate,
             Relation relation, Index rti, int lockmode,
             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, lockmode, LockWaitBlock,
                                  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
 *  wait_policy - requested lock wait policy
 *  *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).
 * We also return NULL if the tuple is locked and the wait policy is to skip
 * such tuples.
 *
 * 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,
                  LockWaitPolicy wait_policy,
                  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;
            HeapUpdateFailureData hufd;

            /*
             * 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.  We assume reading a TransactionId to be
             * atomic, and Xmin never changes in an existing tuple, except to
             * invalid or frozen, and neither of those can match priorXmax.)
             */
            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, or die trying.
             */
            if (TransactionIdIsValid(SnapshotDirty.xmax))
            {
                ReleaseBuffer(buffer);
                switch (wait_policy)
                {
                    case LockWaitBlock:
                        XactLockTableWait(SnapshotDirty.xmax,
                                          relation, &tuple.t_self,
                                          XLTW_FetchUpdated);
                        break;
                    case LockWaitSkip:
                        if (!ConditionalXactLockTableWait(SnapshotDirty.xmax))
                            return NULL;    /* skip instead of waiting */
                        break;
                    case LockWaitError:
                        if (!ConditionalXactLockTableWait(SnapshotDirty.xmax))
                            ereport(ERROR,
                                    (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
                                     errmsg("could not obtain lock on row in relation \"%s\"",
                                            RelationGetRelationName(relation))));
                        break;
                }
                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. Otherwise
             * heap_lock_tuple() will throw an error, and so would any later
             * attempt to update or delete the 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,
                                   estate->es_output_cid,
                                   lockmode, wait_policy,
                                   false, &buffer, &hufd);
            /* We now have two pins on the buffer, get rid of one */
            ReleaseBuffer(buffer);

            switch (test)
            {
                case HeapTupleSelfUpdated:

                    /*
                     * The target tuple was already updated or deleted by the
                     * current command, or by a later command in the current
                     * transaction.  We *must* ignore the tuple in the former
                     * case, so as to avoid the "Halloween problem" of
                     * repeated update attempts.  In the latter case it might
                     * be sensible to fetch the updated tuple instead, but
                     * doing so would require changing heap_update and
                     * heap_delete to not complain about updating "invisible"
                     * tuples, which seems pretty scary (heap_lock_tuple will
                     * not complain, but few callers expect
                     * HeapTupleInvisible, and we're not one of them).  So for
                     * now, treat the tuple as deleted and 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")));

                    /* Should not encounter speculative tuple on recheck */
                    Assert(!HeapTupleHeaderIsSpeculative(tuple.t_data));
                    if (!ItemPointerEquals(&hufd.ctid, &tuple.t_self))
                    {
                        /* it was updated, so look at the updated version */
                        tuple.t_self = hufd.ctid;
                        /* updated row should have xmin matching this xmax */
                        priorXmax = hufd.xmax;
                        continue;
                    }
                    /* tuple was deleted, so give up */
                    return NULL;

                case HeapTupleWouldBlock:
                    ReleaseBuffer(buffer);
                    return NULL;

                case HeapTupleInvisible:
                    elog(ERROR, "attempted to lock invisible tuple");

                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 = HeapTupleHeaderGetUpdateXid(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 ModifyTable 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 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);

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

        if (erm->markType == ROW_MARK_REFERENCE)
        {
            HeapTuple   copyTuple;

            Assert(erm->relation != NULL);

            /* 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;

            /* fetch requests on foreign tables must be passed to their FDW */
            if (erm->relation->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
            {
                FdwRoutine *fdwroutine;
                bool        updated = false;

                fdwroutine = GetFdwRoutineForRelation(erm->relation, false);
                /* this should have been checked already, but let's be safe */
                if (fdwroutine->RefetchForeignRow == NULL)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot lock rows in foreign table \"%s\"",
                                    RelationGetRelationName(erm->relation))));
                copyTuple = fdwroutine->RefetchForeignRow(epqstate->estate,
                                                          erm,
                                                          datum,
                                                          &updated);
                if (copyTuple == NULL)
                    elog(ERROR, "failed to fetch tuple for EvalPlanQual recheck");

                /*
                 * Ideally we'd insist on updated == false here, but that
                 * assumes that FDWs can track that exactly, which they might
                 * not be able to.  So just ignore the flag.
                 */
            }
            else
            {
                /* ordinary table, fetch the tuple */
                Buffer      buffer;

                tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
                if (!heap_fetch(erm->relation, SnapshotAny, &tuple, &buffer,
                                false, NULL))
                    elog(ERROR, "failed to fetch tuple for EvalPlanQual recheck");

                /* successful, copy tuple */
                copyTuple = heap_copytuple(&tuple);
                ReleaseBuffer(buffer);
            }

            /* store tuple */
            EvalPlanQualSetTuple(epqstate, erm->rti, copyTuple);
        }
        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);
            tuple.t_data = td;
            /* relation might be a foreign table, if so provide tableoid */
            tuple.t_tableOid = erm->relid;
            /* also copy t_ctid in case there's valid data there */
            tuple.t_self = td->t_ctid;

            /* 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.
     *
     * The ResultRelInfo array management is trickier than it looks.  We
     * create a fresh array for the child but copy all the content from the
     * parent.  This is because it's okay for the child to share any
     * per-relation state the parent has already created --- but if the child
     * sets up any ResultRelInfo fields, such as its own junkfilter, that
     * state must *not* propagate back to the parent.  (For one thing, the
     * pointed-to data is in a memory context that won't last long enough.)
     */
    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;
    if (parentestate->es_num_result_relations > 0)
    {
        int         numResultRelations = parentestate->es_num_result_relations;
        ResultRelInfo *resultRelInfos;

        resultRelInfos = (ResultRelInfo *)
            palloc(numResultRelations * sizeof(ResultRelInfo));
        memcpy(resultRelInfos, parentestate->es_result_relations,
               numResultRelations * sizeof(ResultRelInfo));
        estate->es_result_relations = resultRelInfos;
        estate->es_num_result_relations = numResultRelations;
    }
    /* es_result_relation_info must NOT be copied */
    /* 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;
    /* 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.
     */
    Assert(estate->es_subplanstates == NIL);
    foreach(l, parentestate->es_plannedstmt->subplans)
    {
        Plan       *subplan = (Plan *) lfirst(l);
        PlanState  *subplanstate;

        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 */
    ExecCleanUpTriggerState(estate);

    MemoryContextSwitchTo(oldcontext);

    FreeExecutorState(estate);

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

/*
 * ExecSetupPartitionTupleRouting - set up information needed during
 * tuple routing for partitioned tables
 *
 * Output arguments:
 * 'pd' receives an array of PartitionDispatch objects with one entry for
 *      every partitioned table in the partition tree
 * 'partitions' receives an array of ResultRelInfo objects with one entry for
 *      every leaf partition in the partition tree
 * 'tup_conv_maps' receives an array of TupleConversionMap objects with one
 *      entry for every leaf partition (required to convert input tuple based
 *      on the root table's rowtype to a leaf partition's rowtype after tuple
 *      routing is done)
 * 'partition_tuple_slot' receives a standalone TupleTableSlot to be used
 *      to manipulate any given leaf partition's rowtype after that partition
 *      is chosen by tuple-routing.
 * 'num_parted' receives the number of partitioned tables in the partition
 *      tree (= the number of entries in the 'pd' output array)
 * 'num_partitions' receives the number of leaf partitions in the partition
 *      tree (= the number of entries in the 'partitions' and 'tup_conv_maps'
 *      output arrays
 *
 * Note that all the relations in the partition tree are locked using the
 * RowExclusiveLock mode upon return from this function.
 */
void
ExecSetupPartitionTupleRouting(Relation rel,
                               Index resultRTindex,
                               EState *estate,
                               PartitionDispatch **pd,
                               ResultRelInfo **partitions,
                               TupleConversionMap ***tup_conv_maps,
                               TupleTableSlot **partition_tuple_slot,
                               int *num_parted, int *num_partitions)
{
    TupleDesc   tupDesc = RelationGetDescr(rel);
    List       *leaf_parts;
    ListCell   *cell;
    int         i;
    ResultRelInfo *leaf_part_rri;

    /*
     * Get the information about the partition tree after locking all the
     * partitions.
     */
    (void) find_all_inheritors(RelationGetRelid(rel), RowExclusiveLock, NULL);
    *pd = RelationGetPartitionDispatchInfo(rel, num_parted, &leaf_parts);
    *num_partitions = list_length(leaf_parts);
    *partitions = (ResultRelInfo *) palloc(*num_partitions *
                                           sizeof(ResultRelInfo));
    *tup_conv_maps = (TupleConversionMap **) palloc0(*num_partitions *
                                                     sizeof(TupleConversionMap *));

    /*
     * Initialize an empty slot that will be used to manipulate tuples of any
     * given partition's rowtype.  It is attached to the caller-specified node
     * (such as ModifyTableState) and released when the node finishes
     * processing.
     */
    *partition_tuple_slot = MakeTupleTableSlot();

    leaf_part_rri = *partitions;
    i = 0;
    foreach(cell, leaf_parts)
    {
        Relation    partrel;
        TupleDesc   part_tupdesc;

        /*
         * We locked all the partitions above including the leaf partitions.
         * Note that each of the relations in *partitions are eventually
         * closed by the caller.
         */
        partrel = heap_open(lfirst_oid(cell), NoLock);
        part_tupdesc = RelationGetDescr(partrel);

        /*
         * Verify result relation is a valid target for the current operation.
         */
        CheckValidResultRel(partrel, CMD_INSERT);

        /*
         * Save a tuple conversion map to convert a tuple routed to this
         * partition from the parent's type to the partition's.
         */
        (*tup_conv_maps)[i] = convert_tuples_by_name(tupDesc, part_tupdesc,
                                                     gettext_noop("could not convert row type"));

        InitResultRelInfo(leaf_part_rri,
                          partrel,
                          resultRTindex,
                          rel,
                          estate->es_instrument);

        estate->es_leaf_result_relations =
            lappend(estate->es_leaf_result_relations, leaf_part_rri);

        /*
         * Open partition indices (remember we do not support ON CONFLICT in
         * case of partitioned tables, so we do not need support information
         * for speculative insertion)
         */
        if (leaf_part_rri->ri_RelationDesc->rd_rel->relhasindex &&
            leaf_part_rri->ri_IndexRelationDescs == NULL)
            ExecOpenIndices(leaf_part_rri, false);

        leaf_part_rri++;
        i++;
    }
}

/*
 * ExecFindPartition -- Find a leaf partition in the partition tree rooted
 * at parent, for the heap tuple contained in *slot
 *
 * estate must be non-NULL; we'll need it to compute any expressions in the
 * partition key(s)
 *
 * If no leaf partition is found, this routine errors out with the appropriate
 * error message, else it returns the leaf partition sequence number returned
 * by get_partition_for_tuple() unchanged.
 */
int
ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
                  TupleTableSlot *slot, EState *estate)
{
    int         result;
    PartitionDispatchData *failed_at;
    TupleTableSlot *failed_slot;

    /*
     * First check the root table's partition constraint, if any.  No point in
     * routing the tuple if it doesn't belong in the root table itself.
     */
    if (resultRelInfo->ri_PartitionCheck)
        ExecPartitionCheck(resultRelInfo, slot, estate);

    result = get_partition_for_tuple(pd, slot, estate,
                                     &failed_at, &failed_slot);
    if (result < 0)
    {
        Relation    failed_rel;
        Datum       key_values[PARTITION_MAX_KEYS];
        bool        key_isnull[PARTITION_MAX_KEYS];
        char       *val_desc;
        ExprContext *ecxt = GetPerTupleExprContext(estate);

        failed_rel = failed_at->reldesc;
        ecxt->ecxt_scantuple = failed_slot;
        FormPartitionKeyDatum(failed_at, failed_slot, estate,
                              key_values, key_isnull);
        val_desc = ExecBuildSlotPartitionKeyDescription(failed_rel,
                                                        key_values,
                                                        key_isnull,
                                                        64);
        Assert(OidIsValid(RelationGetRelid(failed_rel)));
        ereport(ERROR,
                (errcode(ERRCODE_CHECK_VIOLATION),
                 errmsg("no partition of relation \"%s\" found for row",
                        RelationGetRelationName(failed_rel)),
                 val_desc ? errdetail("Partition key of the failing row contains %s.", val_desc) : 0));
    }

    return result;
}

/*
 * BuildSlotPartitionKeyDescription
 *
 * This works very much like BuildIndexValueDescription() and is currently
 * used for building error messages when ExecFindPartition() fails to find
 * partition for a row.
 */
static char *
ExecBuildSlotPartitionKeyDescription(Relation rel,
                                     Datum *values,
                                     bool *isnull,
                                     int maxfieldlen)
{
    StringInfoData buf;
    PartitionKey key = RelationGetPartitionKey(rel);
    int         partnatts = get_partition_natts(key);
    int         i;
    Oid         relid = RelationGetRelid(rel);
    AclResult   aclresult;

    if (check_enable_rls(relid, InvalidOid, true) == RLS_ENABLED)
        return NULL;

    /* If the user has table-level access, just go build the description. */
    aclresult = pg_class_aclcheck(relid, GetUserId(), ACL_SELECT);
    if (aclresult != ACLCHECK_OK)
    {
        /*
         * Step through the columns of the partition key and make sure the
         * user has SELECT rights on all of them.
         */
        for (i = 0; i < partnatts; i++)
        {
            AttrNumber  attnum = get_partition_col_attnum(key, i);

            /*
             * If this partition key column is an expression, we return no
             * detail rather than try to figure out what column(s) the
             * expression includes and if the user has SELECT rights on them.
             */
            if (attnum == InvalidAttrNumber ||
                pg_attribute_aclcheck(relid, attnum, GetUserId(),
                                      ACL_SELECT) != ACLCHECK_OK)
                return NULL;
        }
    }

    initStringInfo(&buf);
    appendStringInfo(&buf, "(%s) = (",
                     pg_get_partkeydef_columns(relid, true));

    for (i = 0; i < partnatts; i++)
    {
        char       *val;
        int         vallen;

        if (isnull[i])
            val = "null";
        else
        {
            Oid         foutoid;
            bool        typisvarlena;

            getTypeOutputInfo(get_partition_col_typid(key, i),
                              &foutoid, &typisvarlena);
            val = OidOutputFunctionCall(foutoid, 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;
}