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) 1996-2025, 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/sysattr.h"
#include "access/table.h"
#include "access/tableam.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "catalog/partition.h"
#include "commands/matview.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "executor/execPartition.h"
#include "executor/nodeSubplan.h"
#include "foreign/fdwapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/queryjumble.h"
#include "parser/parse_relation.h"
#include "pgstat.h"
#include "rewrite/rewriteHandler.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/backend_status.h"
#include "utils/lsyscache.h"
#include "utils/partcache.h"
#include "utils/rls.h"
#include "utils/snapmgr.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 ExecCheckPermissions() */
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(QueryDesc *queryDesc,
                        CmdType operation,
                        bool sendTuples,
                        uint64 numberTuples,
                        ScanDirection direction,
                        DestReceiver *dest);
static bool ExecCheckOneRelPerms(RTEPermissionInfo *perminfo);
static bool ExecCheckPermissionsModified(Oid relOid, Oid userid,
                                         Bitmapset *modifiedCols,
                                         AclMode requiredPerms);
static void ExecCheckXactReadOnly(PlannedStmt *plannedstmt);
static void EvalPlanQualStart(EPQState *epqstate, Plan *planTree);
static void ReportNotNullViolationError(ResultRelInfo *resultRelInfo,
                                        TupleTableSlot *slot,
                                        EState *estate, int attnum);
 
/* 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)
{
    /*
     * In some cases (e.g. an EXECUTE statement or an execute message with the
     * extended query protocol) the query_id won't be reported, so do it now.
     *
     * Note that it's harmless to report the query_id multiple times, as the
     * call will be ignored if the top level query_id has already been
     * reported.
     */
    pgstat_report_query_id(queryDesc->plannedstmt->queryId, false);
 
    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);
 
    /* caller must ensure the query's snapshot is active */
    Assert(GetActiveSnapshot() == queryDesc->snapshot);
 
    /*
     * 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 combo CID 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->paramExecTypes != NIL)
    {
        int         nParamExec;
 
        nParamExec = list_length(queryDesc->plannedstmt->paramExecTypes);
        estate->es_param_exec_vals = (ParamExecData *)
            palloc0(nParamExec * sizeof(ParamExecData));
    }
 
    /* We now require all callers to provide sourceText */
    Assert(queryDesc->sourceText != NULL);
    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:
        case CMD_MERGE:
            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;
    estate->es_jit_flags = queryDesc->plannedstmt->jitFlags;
 
    /*
     * 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();
 
    /*
     * Initialize the plan state tree
     */
    InitPlan(queryDesc, eflags);
 
    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.  The total number of tuples processed in all
 *      the ExecutorRun calls can be found in estate->es_total_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)
{
    if (ExecutorRun_hook)
        (*ExecutorRun_hook) (queryDesc, direction, count);
    else
        standard_ExecutorRun(queryDesc, direction, count);
}
 
void
standard_ExecutorRun(QueryDesc *queryDesc,
                     ScanDirection direction, uint64 count)
{
    EState     *estate;
    CmdType     operation;
    DestReceiver *dest;
    bool        sendTuples;
    MemoryContext oldcontext;
 
    /* sanity checks */
    Assert(queryDesc != NULL);
 
    estate = queryDesc->estate;
 
    Assert(estate != NULL);
    Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
 
    /* caller must ensure the query's snapshot is active */
    Assert(GetActiveSnapshot() == estate->es_snapshot);
 
    /*
     * 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;
 
    sendTuples = (operation == CMD_SELECT ||
                  queryDesc->plannedstmt->hasReturning);
 
    if (sendTuples)
        dest->rStartup(dest, operation, queryDesc->tupDesc);
 
    /*
     * Run plan, unless direction is NoMovement.
     *
     * Note: pquery.c selects NoMovement if a prior call already reached
     * end-of-data in the user-specified fetch direction.  This is important
     * because various parts of the executor can misbehave if called again
     * after reporting EOF.  For example, heapam.c would actually restart a
     * heapscan and return all its data afresh.  There is also some doubt
     * about whether a parallel plan would operate properly if an additional,
     * necessarily non-parallel execution request occurs after completing a
     * parallel execution.  (That case should work, but it's untested.)
     */
    if (!ScanDirectionIsNoMovement(direction))
        ExecutePlan(queryDesc,
                    operation,
                    sendTuples,
                    count,
                    direction,
                    dest);
 
    /*
     * Update es_total_processed to keep track of the number of tuples
     * processed across multiple ExecutorRun() calls.
     */
    estate->es_total_processed += estate->es_processed;
 
    /*
     * 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);
 
    if (estate->es_parallel_workers_to_launch > 0)
        pgstat_update_parallel_workers_stats((PgStat_Counter) estate->es_parallel_workers_to_launch,
                                             (PgStat_Counter) estate->es_parallel_workers_launched);
 
    /*
     * 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);
}
 
 
/*
 * ExecCheckPermissions
 *      Check access permissions of relations mentioned in a query
 *
 * 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.
 *
 * NB: rangeTable is no longer used by us, but kept around for the hooks that
 * might still want to look at the RTEs.
 */
bool
ExecCheckPermissions(List *rangeTable, List *rteperminfos,
                     bool ereport_on_violation)
{
    ListCell   *l;
    bool        result = true;
 
#ifdef USE_ASSERT_CHECKING
    Bitmapset  *indexset = NULL;
 
    /* Check that rteperminfos is consistent with rangeTable */
    foreach(l, rangeTable)
    {
        RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
 
        if (rte->perminfoindex != 0)
        {
            /* Sanity checks */
 
            /*
             * Only relation RTEs and subquery RTEs that were once relation
             * RTEs (views) have their perminfoindex set.
             */
            Assert(rte->rtekind == RTE_RELATION ||
                   (rte->rtekind == RTE_SUBQUERY &&
                    rte->relkind == RELKIND_VIEW));
 
            (void) getRTEPermissionInfo(rteperminfos, rte);
            /* Many-to-one mapping not allowed */
            Assert(!bms_is_member(rte->perminfoindex, indexset));
            indexset = bms_add_member(indexset, rte->perminfoindex);
        }
    }
 
    /* All rteperminfos are referenced */
    Assert(bms_num_members(indexset) == list_length(rteperminfos));
#endif
 
    foreach(l, rteperminfos)
    {
        RTEPermissionInfo *perminfo = lfirst_node(RTEPermissionInfo, l);
 
        Assert(OidIsValid(perminfo->relid));
        result = ExecCheckOneRelPerms(perminfo);
        if (!result)
        {
            if (ereport_on_violation)
                aclcheck_error(ACLCHECK_NO_PRIV,
                               get_relkind_objtype(get_rel_relkind(perminfo->relid)),
                               get_rel_name(perminfo->relid));
            return false;
        }
    }
 
    if (ExecutorCheckPerms_hook)
        result = (*ExecutorCheckPerms_hook) (rangeTable, rteperminfos,
                                             ereport_on_violation);
    return result;
}
 
/*
 * ExecCheckOneRelPerms
 *      Check access permissions for a single relation.
 */
static bool
ExecCheckOneRelPerms(RTEPermissionInfo *perminfo)
{
    AclMode     requiredPerms;
    AclMode     relPerms;
    AclMode     remainingPerms;
    Oid         userid;
    Oid         relOid = perminfo->relid;
 
    requiredPerms = perminfo->requiredPerms;
    Assert(requiredPerms != 0);
 
    /*
     * 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 relation.  If that stops being true, we
     * could call it once in ExecCheckPermissions and pass the userid down
     * from there.  But for now, no need for the extra clutter.
     */
    userid = OidIsValid(perminfo->checkAsUser) ?
        perminfo->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(perminfo->selectedCols))
            {
                if (pg_attribute_aclcheck_all(relOid, userid, ACL_SELECT,
                                              ACLMASK_ANY) != ACLCHECK_OK)
                    return false;
            }
 
            while ((col = bms_next_member(perminfo->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 &&
            !ExecCheckPermissionsModified(relOid,
                                          userid,
                                          perminfo->insertedCols,
                                          ACL_INSERT))
            return false;
 
        if (remainingPerms & ACL_UPDATE &&
            !ExecCheckPermissionsModified(relOid,
                                          userid,
                                          perminfo->updatedCols,
                                          ACL_UPDATE))
            return false;
    }
    return true;
}
 
/*
 * ExecCheckPermissionsModified
 *      Check INSERT or UPDATE access permissions for a single relation (these
 *      are processed uniformly).
 */
static bool
ExecCheckPermissionsModified(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->permInfos)
    {
        RTEPermissionInfo *perminfo = lfirst_node(RTEPermissionInfo, l);
 
        if ((perminfo->requiredPerms & (~ACL_SELECT)) == 0)
            continue;
 
        if (isTempNamespace(get_rel_namespace(perminfo->relid)))
            continue;
 
        PreventCommandIfReadOnly(CreateCommandName((Node *) plannedstmt));
    }
 
    if (plannedstmt->commandType != CMD_SELECT || plannedstmt->hasModifyingCTE)
        PreventCommandIfParallelMode(CreateCommandName((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
     */
    ExecCheckPermissions(rangeTable, plannedstmt->permInfos, true);
 
    /*
     * initialize the node's execution state
     */
    ExecInitRangeTable(estate, rangeTable, plannedstmt->permInfos,
                       bms_copy(plannedstmt->unprunableRelids));
 
    estate->es_plannedstmt = plannedstmt;
    estate->es_part_prune_infos = plannedstmt->partPruneInfos;
 
    /*
     * Perform runtime "initial" pruning to identify which child subplans,
     * corresponding to the children of plan nodes that contain
     * PartitionPruneInfo such as Append, will not be executed. The results,
     * which are bitmapsets of indexes of the child subplans that will be
     * executed, are saved in es_part_prune_results.  These results correspond
     * to each PartitionPruneInfo entry, and the es_part_prune_results list is
     * parallel to es_part_prune_infos.
     */
    ExecDoInitialPruning(estate);
 
    /*
     * Next, build the ExecRowMark array from the PlanRowMark(s), if any.
     */
    if (plannedstmt->rowMarks)
    {
        estate->es_rowmarks = (ExecRowMark **)
            palloc0(estate->es_range_table_size * sizeof(ExecRowMark *));
        foreach(l, plannedstmt->rowMarks)
        {
            PlanRowMark *rc = (PlanRowMark *) lfirst(l);
            Oid         relid;
            Relation    relation;
            ExecRowMark *erm;
 
            /*
             * Ignore "parent" rowmarks, because they are irrelevant at
             * runtime.  Also ignore the rowmarks belonging to child tables
             * that have been pruned in ExecDoInitialPruning().
             */
            if (rc->isParent ||
                !bms_is_member(rc->rti, estate->es_unpruned_relids))
                continue;
 
            /* get relation's OID (will produce InvalidOid if subquery) */
            relid = exec_rt_fetch(rc->rti, estate)->relid;
 
            /* open relation, if we need to access it for this mark type */
            switch (rc->markType)
            {
                case ROW_MARK_EXCLUSIVE:
                case ROW_MARK_NOKEYEXCLUSIVE:
                case ROW_MARK_SHARE:
                case ROW_MARK_KEYSHARE:
                case ROW_MARK_REFERENCE:
                    relation = ExecGetRangeTableRelation(estate, rc->rti, false);
                    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;
 
            Assert(erm->rti > 0 && erm->rti <= estate->es_range_table_size &&
                   estate->es_rowmarks[erm->rti - 1] == NULL);
 
            estate->es_rowmarks[erm->rti - 1] = erm;
        }
    }
 
    /*
     * Initialize the executor's tuple table to empty.
     */
    estate->es_tupleTable = NIL;
 
    /* signal that this EState is not used for EPQ */
    estate->es_epq_active = 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_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
        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;
            TupleTableSlot *slot;
 
            slot = ExecInitExtraTupleSlot(estate, NULL, &TTSOpsVirtual);
            j = ExecInitJunkFilter(planstate->plan->targetlist,
                                   slot);
            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.
 *
 * For MERGE, mergeActions is the list of actions that may be performed.  The
 * result relation is required to support every action, regardless of whether
 * or not they are all executed.
 *
 * Note: when changing this function, you probably also need to look at
 * CheckValidRowMarkRel.
 */
void
CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation,
                    List *mergeActions)
{
    Relation    resultRel = resultRelInfo->ri_RelationDesc;
    FdwRoutine *fdwroutine;
 
    /* Expect a fully-formed ResultRelInfo from InitResultRelInfo(). */
    Assert(resultRelInfo->ri_needLockTagTuple ==
           IsInplaceUpdateRelation(resultRel));
 
    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.  Otherwise,
             * complain, but omit errdetail because we haven't got the
             * information handy (and given that it really shouldn't happen,
             * it's not worth great exertion to get).
             */
            if (!view_has_instead_trigger(resultRel, operation, mergeActions))
                error_view_not_updatable(resultRel, operation, mergeActions,
                                         NULL);
            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 = resultRelInfo->ri_FdwRoutine;
            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,
                  ResultRelInfo *partition_root_rri,
                  int instrument_options)
{
    MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
    resultRelInfo->type = T_ResultRelInfo;
    resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
    resultRelInfo->ri_RelationDesc = resultRelationDesc;
    resultRelInfo->ri_NumIndices = 0;
    resultRelInfo->ri_IndexRelationDescs = NULL;
    resultRelInfo->ri_IndexRelationInfo = NULL;
    resultRelInfo->ri_needLockTagTuple =
        IsInplaceUpdateRelation(resultRelationDesc);
    /* 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, false);
    }
    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;
 
    /* The following fields are set later if needed */
    resultRelInfo->ri_RowIdAttNo = 0;
    resultRelInfo->ri_extraUpdatedCols = NULL;
    resultRelInfo->ri_projectNew = NULL;
    resultRelInfo->ri_newTupleSlot = NULL;
    resultRelInfo->ri_oldTupleSlot = NULL;
    resultRelInfo->ri_projectNewInfoValid = false;
    resultRelInfo->ri_FdwState = NULL;
    resultRelInfo->ri_usesFdwDirectModify = false;
    resultRelInfo->ri_CheckConstraintExprs = NULL;
    resultRelInfo->ri_GenVirtualNotNullConstraintExprs = NULL;
    resultRelInfo->ri_GeneratedExprsI = NULL;
    resultRelInfo->ri_GeneratedExprsU = NULL;
    resultRelInfo->ri_projectReturning = NULL;
    resultRelInfo->ri_onConflictArbiterIndexes = NIL;
    resultRelInfo->ri_onConflict = NULL;
    resultRelInfo->ri_ReturningSlot = NULL;
    resultRelInfo->ri_TrigOldSlot = NULL;
    resultRelInfo->ri_TrigNewSlot = NULL;
    resultRelInfo->ri_AllNullSlot = NULL;
    resultRelInfo->ri_MergeActions[MERGE_WHEN_MATCHED] = NIL;
    resultRelInfo->ri_MergeActions[MERGE_WHEN_NOT_MATCHED_BY_SOURCE] = NIL;
    resultRelInfo->ri_MergeActions[MERGE_WHEN_NOT_MATCHED_BY_TARGET] = NIL;
    resultRelInfo->ri_MergeJoinCondition = NULL;
 
    /*
     * Only ExecInitPartitionInfo() and ExecInitPartitionDispatchInfo() pass
     * non-NULL partition_root_rri.  For child relations that are part of the
     * initial query rather than being dynamically added by tuple routing,
     * this field is filled in ExecInitModifyTable().
     */
    resultRelInfo->ri_RootResultRelInfo = partition_root_rri;
    /* Set by ExecGetRootToChildMap */
    resultRelInfo->ri_RootToChildMap = NULL;
    resultRelInfo->ri_RootToChildMapValid = false;
    /* Set by ExecInitRoutingInfo */
    resultRelInfo->ri_PartitionTupleSlot = NULL;
    resultRelInfo->ri_ChildToRootMap = NULL;
    resultRelInfo->ri_ChildToRootMapValid = false;
    resultRelInfo->ri_CopyMultiInsertBuffer = NULL;
}
 
/*
 * ExecGetTriggerResultRel
 *      Get a ResultRelInfo for a trigger target relation.
 *
 * Most of the time, triggers are fired on one of the result relations of the
 * query, and so we can just return a member of the es_result_relations array,
 * or the es_tuple_routing_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 *rootRelInfo)
{
    ResultRelInfo *rInfo;
    ListCell   *l;
    Relation    rel;
    MemoryContext oldcontext;
 
    /* Search through the query result relations */
    foreach(l, estate->es_opened_result_relations)
    {
        rInfo = lfirst(l);
        if (RelationGetRelid(rInfo->ri_RelationDesc) == relid)
            return rInfo;
    }
 
    /*
     * Search through the result relations that were created during tuple
     * routing, if any.
     */
    foreach(l, estate->es_tuple_routing_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 = table_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 */
                      rootRelInfo,
                      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;
}
 
/*
 * Return the ancestor relations of a given leaf partition result relation
 * up to and including the query's root target relation.
 *
 * These work much like the ones opened by ExecGetTriggerResultRel, except
 * that we need to keep them in a separate list.
 *
 * These are closed by ExecCloseResultRelations.
 */
List *
ExecGetAncestorResultRels(EState *estate, ResultRelInfo *resultRelInfo)
{
    ResultRelInfo *rootRelInfo = resultRelInfo->ri_RootResultRelInfo;
    Relation    partRel = resultRelInfo->ri_RelationDesc;
    Oid         rootRelOid;
 
    if (!partRel->rd_rel->relispartition)
        elog(ERROR, "cannot find ancestors of a non-partition result relation");
    Assert(rootRelInfo != NULL);
    rootRelOid = RelationGetRelid(rootRelInfo->ri_RelationDesc);
    if (resultRelInfo->ri_ancestorResultRels == NIL)
    {
        ListCell   *lc;
        List       *oids = get_partition_ancestors(RelationGetRelid(partRel));
        List       *ancResultRels = NIL;
 
        foreach(lc, oids)
        {
            Oid         ancOid = lfirst_oid(lc);
            Relation    ancRel;
            ResultRelInfo *rInfo;
 
            /*
             * Ignore the root ancestor here, and use ri_RootResultRelInfo
             * (below) for it instead.  Also, we stop climbing up the
             * hierarchy when we find the table that was mentioned in the
             * query.
             */
            if (ancOid == rootRelOid)
                break;
 
            /*
             * All ancestors up to the root target relation must have been
             * locked by the planner or AcquireExecutorLocks().
             */
            ancRel = table_open(ancOid, NoLock);
            rInfo = makeNode(ResultRelInfo);
 
            /* dummy rangetable index */
            InitResultRelInfo(rInfo, ancRel, 0, NULL,
                              estate->es_instrument);
            ancResultRels = lappend(ancResultRels, rInfo);
        }
        ancResultRels = lappend(ancResultRels, rootRelInfo);
        resultRelInfo->ri_ancestorResultRels = ancResultRels;
    }
 
    /* We must have found some ancestor */
    Assert(resultRelInfo->ri_ancestorResultRels != NIL);
 
    return resultRelInfo->ri_ancestorResultRels;
}
 
/* ----------------------------------------------------------------
 *      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)
{
    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 any Relations that have been opened for range table entries or
     * result relations.
     */
    ExecCloseResultRelations(estate);
    ExecCloseRangeTableRelations(estate);
}
 
/*
 * Close any relations that have been opened for ResultRelInfos.
 */
void
ExecCloseResultRelations(EState *estate)
{
    ListCell   *l;
 
    /*
     * close indexes of result relation(s) if any.  (Rels themselves are
     * closed in ExecCloseRangeTableRelations())
     *
     * In addition, close the stub RTs that may be in each resultrel's
     * ri_ancestorResultRels.
     */
    foreach(l, estate->es_opened_result_relations)
    {
        ResultRelInfo *resultRelInfo = lfirst(l);
        ListCell   *lc;
 
        ExecCloseIndices(resultRelInfo);
        foreach(lc, resultRelInfo->ri_ancestorResultRels)
        {
            ResultRelInfo *rInfo = lfirst(lc);
 
            /*
             * Ancestors with RTI > 0 (should only be the root ancestor) are
             * closed by ExecCloseRangeTableRelations.
             */
            if (rInfo->ri_RangeTableIndex > 0)
                continue;
 
            table_close(rInfo->ri_RelationDesc, NoLock);
        }
    }
 
    /* Close any relations that have been opened by ExecGetTriggerResultRel(). */
    foreach(l, estate->es_trig_target_relations)
    {
        ResultRelInfo *resultRelInfo = (ResultRelInfo *) lfirst(l);
 
        /*
         * Assert this is a "dummy" ResultRelInfo, see above.  Otherwise we
         * might be issuing a duplicate close against a Relation opened by
         * ExecGetRangeTableRelation.
         */
        Assert(resultRelInfo->ri_RangeTableIndex == 0);
 
        /*
         * Since ExecGetTriggerResultRel doesn't call ExecOpenIndices for
         * these rels, we needn't call ExecCloseIndices either.
         */
        Assert(resultRelInfo->ri_NumIndices == 0);
 
        table_close(resultRelInfo->ri_RelationDesc, NoLock);
    }
}
 
/*
 * Close all relations opened by ExecGetRangeTableRelation().
 *
 * We do not release any locks we might hold on those rels.
 */
void
ExecCloseRangeTableRelations(EState *estate)
{
    int         i;
 
    for (i = 0; i < estate->es_range_table_size; i++)
    {
        if (estate->es_relations[i])
            table_close(estate->es_relations[i], NoLock);
    }
}
 
/* ----------------------------------------------------------------
 *      ExecutePlan
 *
 *      Processes the query plan until we have retrieved 'numberTuples' tuples,
 *      moving in the specified direction.
 *
 *      Runs to completion if numberTuples is 0
 * ----------------------------------------------------------------
 */
static void
ExecutePlan(QueryDesc *queryDesc,
            CmdType operation,
            bool sendTuples,
            uint64 numberTuples,
            ScanDirection direction,
            DestReceiver *dest)
{
    EState     *estate = queryDesc->estate;
    PlanState  *planstate = queryDesc->planstate;
    bool        use_parallel_mode;
    TupleTableSlot *slot;
    uint64      current_tuple_count;
 
    /*
     * initialize local variables
     */
    current_tuple_count = 0;
 
    /*
     * Set the direction.
     */
    estate->es_direction = direction;
 
    /*
     * Set up parallel mode if appropriate.
     *
     * Parallel mode only supports complete execution of a plan.  If we've
     * already partially executed it, or if the caller asks us to exit early,
     * we must force the plan to run without parallelism.
     */
    if (queryDesc->already_executed || numberTuples != 0)
        use_parallel_mode = false;
    else
        use_parallel_mode = queryDesc->plannedstmt->parallelModeNeeded;
    queryDesc->already_executed = true;
 
    estate->es_use_parallel_mode = use_parallel_mode;
    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))
            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)
            break;
    }
 
    /*
     * If we know we won't need to back up, we can release resources at this
     * point.
     */
    if (!(estate->es_top_eflags & EXEC_FLAG_BACKWARD))
        ExecShutdownNode(planstate);
 
    if (use_parallel_mode)
        ExitParallelMode();
}
 
 
/*
 * ExecRelCheck --- check that tuple meets check 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;
 
    /*
     * CheckNNConstraintFetch let this pass with only a warning, but now we
     * should fail rather than possibly failing to enforce an important
     * constraint.
     */
    if (ncheck != rel->rd_rel->relchecks)
        elog(ERROR, "%d pg_constraint record(s) missing for relation \"%s\"",
             rel->rd_rel->relchecks - ncheck, RelationGetRelationName(rel));
 
    /*
     * 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_CheckConstraintExprs == NULL)
    {
        oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
        resultRelInfo->ri_CheckConstraintExprs = palloc0_array(ExprState *, ncheck);
        for (int i = 0; i < ncheck; i++)
        {
            Expr       *checkconstr;
 
            /* Skip not enforced constraint */
            if (!check[i].ccenforced)
                continue;
 
            checkconstr = stringToNode(check[i].ccbin);
            checkconstr = (Expr *) expand_generated_columns_in_expr((Node *) checkconstr, rel, 1);
            resultRelInfo->ri_CheckConstraintExprs[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 (int i = 0; i < ncheck; i++)
    {
        ExprState  *checkconstr = resultRelInfo->ri_CheckConstraintExprs[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 (checkconstr && !ExecCheck(checkconstr, econtext))
            return check[i].ccname;
    }
 
    /* NULL result means no error */
    return NULL;
}
 
/*
 * ExecPartitionCheck --- check that tuple meets the partition constraint.
 *
 * Returns true if it meets the partition constraint.  If the constraint
 * fails and we're asked to emit an error, do so and don't return; otherwise
 * return false.
 */
bool
ExecPartitionCheck(ResultRelInfo *resultRelInfo, TupleTableSlot *slot,
                   EState *estate, bool emitError)
{
    ExprContext *econtext;
    bool        success;
 
    /*
     * If first time through, build expression state tree for the partition
     * check expression.  (In the corner case where the partition check
     * expression is empty, ie there's a default partition and nothing else,
     * we'll be fooled into executing this code each time through.  But it's
     * pretty darn cheap in that case, so we don't worry about it.)
     */
    if (resultRelInfo->ri_PartitionCheckExpr == NULL)
    {
        /*
         * Ensure that the qual tree and prepared expression are in the
         * query-lifespan context.
         */
        MemoryContext oldcxt = MemoryContextSwitchTo(estate->es_query_cxt);
        List       *qual = RelationGetPartitionQual(resultRelInfo->ri_RelationDesc);
 
        resultRelInfo->ri_PartitionCheckExpr = ExecPrepareCheck(qual, estate);
        MemoryContextSwitchTo(oldcxt);
    }
 
    /*
     * 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 cataloged constraints, we treat a NULL result as
     * success here, not a failure.
     */
    success = ExecCheck(resultRelInfo->ri_PartitionCheckExpr, econtext);
 
    /* if asked to emit error, don't actually return on failure */
    if (!success && emitError)
        ExecPartitionCheckEmitError(resultRelInfo, slot, estate);
 
    return success;
}
 
/*
 * ExecPartitionCheckEmitError - Form and emit an error message after a failed
 * partition constraint check.
 */
void
ExecPartitionCheckEmitError(ResultRelInfo *resultRelInfo,
                            TupleTableSlot *slot,
                            EState *estate)
{
    Oid         root_relid;
    TupleDesc   tupdesc;
    char       *val_desc;
    Bitmapset  *modifiedCols;
 
    /*
     * 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 in the error message
     * matches the input tuple.
     */
    if (resultRelInfo->ri_RootResultRelInfo)
    {
        ResultRelInfo *rootrel = resultRelInfo->ri_RootResultRelInfo;
        TupleDesc   old_tupdesc;
        AttrMap    *map;
 
        root_relid = RelationGetRelid(rootrel->ri_RelationDesc);
        tupdesc = RelationGetDescr(rootrel->ri_RelationDesc);
 
        old_tupdesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
        /* a reverse map */
        map = build_attrmap_by_name_if_req(old_tupdesc, tupdesc, false);
 
        /*
         * Partition-specific slot's tupdesc can't be changed, so allocate a
         * new one.
         */
        if (map != NULL)
            slot = execute_attr_map_slot(map, slot,
                                         MakeTupleTableSlot(tupdesc, &TTSOpsVirtual));
        modifiedCols = bms_union(ExecGetInsertedCols(rootrel, estate),
                                 ExecGetUpdatedCols(rootrel, estate));
    }
    else
    {
        root_relid = RelationGetRelid(resultRelInfo->ri_RelationDesc);
        tupdesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
        modifiedCols = bms_union(ExecGetInsertedCols(resultRelInfo, estate),
                                 ExecGetUpdatedCols(resultRelInfo, estate));
    }
 
    val_desc = ExecBuildSlotValueDescription(root_relid,
                                             slot,
                                             tupdesc,
                                             modifiedCols,
                                             64);
    ereport(ERROR,
            (errcode(ERRCODE_CHECK_VIOLATION),
             errmsg("new row for relation \"%s\" violates partition constraint",
                    RelationGetRelationName(resultRelInfo->ri_RelationDesc)),
             val_desc ? errdetail("Failing row contains %s.", val_desc) : 0,
             errtable(resultRelInfo->ri_RelationDesc)));
}
 
/*
 * ExecConstraints - check constraints of the tuple in 'slot'
 *
 * This checks the traditional NOT NULL and check constraints.
 *
 * The partition constraint is *NOT* checked.
 *
 * 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 final result relation, after 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;
    List       *notnull_virtual_attrs = NIL;
 
    Assert(constr);             /* we should not be called otherwise */
 
    /*
     * Verify not-null constraints.
     *
     * Not-null constraints on virtual generated columns are collected and
     * checked separately below.
     */
    if (constr->has_not_null)
    {
        for (AttrNumber attnum = 1; attnum <= tupdesc->natts; attnum++)
        {
            Form_pg_attribute att = TupleDescAttr(tupdesc, attnum - 1);
 
            if (att->attnotnull && att->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
                notnull_virtual_attrs = lappend_int(notnull_virtual_attrs, attnum);
            else if (att->attnotnull && slot_attisnull(slot, attnum))
                ReportNotNullViolationError(resultRelInfo, slot, estate, attnum);
        }
    }
 
    /*
     * Verify not-null constraints on virtual generated column, if any.
     */
    if (notnull_virtual_attrs)
    {
        AttrNumber  attnum;
 
        attnum = ExecRelGenVirtualNotNull(resultRelInfo, slot, estate,
                                          notnull_virtual_attrs);
        if (attnum != InvalidAttrNumber)
            ReportNotNullViolationError(resultRelInfo, slot, estate, attnum);
    }
 
    /*
     * Verify check constraints.
     */
    if (rel->rd_rel->relchecks > 0)
    {
        const char *failed;
 
        if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
        {
            char       *val_desc;
            Relation    orig_rel = 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_RootResultRelInfo)
            {
                ResultRelInfo *rootrel = resultRelInfo->ri_RootResultRelInfo;
                TupleDesc   old_tupdesc = RelationGetDescr(rel);
                AttrMap    *map;
 
                tupdesc = RelationGetDescr(rootrel->ri_RelationDesc);
                /* a reverse map */
                map = build_attrmap_by_name_if_req(old_tupdesc,
                                                   tupdesc,
                                                   false);
 
                /*
                 * Partition-specific slot's tupdesc can't be changed, so
                 * allocate a new one.
                 */
                if (map != NULL)
                    slot = execute_attr_map_slot(map, slot,
                                                 MakeTupleTableSlot(tupdesc, &TTSOpsVirtual));
                modifiedCols = bms_union(ExecGetInsertedCols(rootrel, estate),
                                         ExecGetUpdatedCols(rootrel, estate));
                rel = rootrel->ri_RelationDesc;
            }
            else
                modifiedCols = bms_union(ExecGetInsertedCols(resultRelInfo, estate),
                                         ExecGetUpdatedCols(resultRelInfo, estate));
            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)));
        }
    }
}
 
/*
 * Verify not-null constraints on virtual generated columns of the given
 * tuple slot.
 *
 * Return value of InvalidAttrNumber means all not-null constraints on virtual
 * generated columns are satisfied.  A return value > 0 means a not-null
 * violation happened for that attribute.
 *
 * notnull_virtual_attrs is the list of the attnums of virtual generated column with
 * not-null constraints.
 */
AttrNumber
ExecRelGenVirtualNotNull(ResultRelInfo *resultRelInfo, TupleTableSlot *slot,
                         EState *estate, List *notnull_virtual_attrs)
{
    Relation    rel = resultRelInfo->ri_RelationDesc;
    ExprContext *econtext;
    MemoryContext oldContext;
 
    /*
     * We implement this by building a NullTest node for each virtual
     * generated column, which we cache in resultRelInfo, and running those
     * through ExecCheck().
     */
    if (resultRelInfo->ri_GenVirtualNotNullConstraintExprs == NULL)
    {
        oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
        resultRelInfo->ri_GenVirtualNotNullConstraintExprs =
            palloc0_array(ExprState *, list_length(notnull_virtual_attrs));
 
        foreach_int(attnum, notnull_virtual_attrs)
        {
            int         i = foreach_current_index(attnum);
            NullTest   *nnulltest;
 
            /* "generated_expression IS NOT NULL" check. */
            nnulltest = makeNode(NullTest);
            nnulltest->arg = (Expr *) build_generation_expression(rel, attnum);
            nnulltest->nulltesttype = IS_NOT_NULL;
            nnulltest->argisrow = false;
            nnulltest->location = -1;
 
            resultRelInfo->ri_GenVirtualNotNullConstraintExprs[i] =
                ExecPrepareExpr((Expr *) nnulltest, estate);
        }
        MemoryContextSwitchTo(oldContext);
    }
 
    /*
     * We will use the EState's per-tuple context for evaluating virtual
     * generated column not null 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 check constraints for virtual generated column */
    foreach_int(attnum, notnull_virtual_attrs)
    {
        int         i = foreach_current_index(attnum);
        ExprState  *exprstate = resultRelInfo->ri_GenVirtualNotNullConstraintExprs[i];
 
        Assert(exprstate != NULL);
        if (!ExecCheck(exprstate, econtext))
            return attnum;
    }
 
    /* InvalidAttrNumber result means no error */
    return InvalidAttrNumber;
}
 
/*
 * Report a violation of a not-null constraint that was already detected.
 */
static void
ReportNotNullViolationError(ResultRelInfo *resultRelInfo, TupleTableSlot *slot,
                            EState *estate, int attnum)
{
    Bitmapset  *modifiedCols;
    char       *val_desc;
    Relation    rel = resultRelInfo->ri_RelationDesc;
    Relation    orig_rel = rel;
    TupleDesc   tupdesc = RelationGetDescr(rel);
    TupleDesc   orig_tupdesc = RelationGetDescr(rel);
    Form_pg_attribute att = TupleDescAttr(tupdesc, attnum - 1);
 
    Assert(attnum > 0);
 
    /*
     * 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_RootResultRelInfo)
    {
        ResultRelInfo *rootrel = resultRelInfo->ri_RootResultRelInfo;
        AttrMap    *map;
 
        tupdesc = RelationGetDescr(rootrel->ri_RelationDesc);
        /* a reverse map */
        map = build_attrmap_by_name_if_req(orig_tupdesc,
                                           tupdesc,
                                           false);
 
        /*
         * Partition-specific slot's tupdesc can't be changed, so allocate a
         * new one.
         */
        if (map != NULL)
            slot = execute_attr_map_slot(map, slot,
                                         MakeTupleTableSlot(tupdesc, &TTSOpsVirtual));
        modifiedCols = bms_union(ExecGetInsertedCols(rootrel, estate),
                                 ExecGetUpdatedCols(rootrel, estate));
        rel = rootrel->ri_RelationDesc;
    }
    else
        modifiedCols = bms_union(ExecGetInsertedCols(resultRelInfo, estate),
                                 ExecGetUpdatedCols(resultRelInfo, estate));
 
    val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
                                             slot,
                                             tupdesc,
                                             modifiedCols,
                                             64);
    ereport(ERROR,
            errcode(ERRCODE_NOT_NULL_VIOLATION),
            errmsg("null value in column \"%s\" of relation \"%s\" violates not-null constraint",
                   NameStr(att->attname),
                   RelationGetRelationName(orig_rel)),
            val_desc ? errdetail("Failing row contains %s.", val_desc) : 0,
            errtablecol(orig_rel, attnum));
}
 
/*
 * 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;
 
            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_RootResultRelInfo)
                    {
                        ResultRelInfo *rootrel = resultRelInfo->ri_RootResultRelInfo;
                        TupleDesc   old_tupdesc = RelationGetDescr(rel);
                        AttrMap    *map;
 
                        tupdesc = RelationGetDescr(rootrel->ri_RelationDesc);
                        /* a reverse map */
                        map = build_attrmap_by_name_if_req(old_tupdesc,
                                                           tupdesc,
                                                           false);
 
                        /*
                         * Partition-specific slot's tupdesc can't be changed,
                         * so allocate a new one.
                         */
                        if (map != NULL)
                            slot = execute_attr_map_slot(map, slot,
                                                         MakeTupleTableSlot(tupdesc, &TTSOpsVirtual));
 
                        modifiedCols = bms_union(ExecGetInsertedCols(rootrel, estate),
                                                 ExecGetUpdatedCols(rootrel, estate));
                        rel = rootrel->ri_RelationDesc;
                    }
                    else
                        modifiedCols = bms_union(ExecGetInsertedCols(resultRelInfo, estate),
                                                 ExecGetUpdatedCols(resultRelInfo, estate));
                    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_MERGE_UPDATE_CHECK:
                case WCO_RLS_MERGE_DELETE_CHECK:
                    if (wco->polname != NULL)
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("target row violates row-level security policy \"%s\" (USING expression) for table \"%s\"",
                                        wco->polname, wco->relname)));
                    else
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("target row violates row-level security policy (USING expression) 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.
 */
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 (att->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
                val = "virtual";
            else 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)
                appendBinaryStringInfo(&buf, val, vallen);
            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, ") = ");
        appendBinaryStringInfo(&collist, buf.data, buf.len);
 
        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 = ExecGetAllUpdatedCols(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)
{
    if (rti > 0 && rti <= estate->es_range_table_size &&
        estate->es_rowmarks != NULL)
    {
        ExecRowMark *erm = estate->es_rowmarks[rti - 1];
 
        if (erm)
            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 the updated version of a tuple to see if we want to process it under
 * READ COMMITTED rules.
 *
 *  epqstate - state for EvalPlanQual rechecking
 *  relation - table containing tuple
 *  rti - rangetable index of table containing tuple
 *  inputslot - tuple for processing - this can be the slot from
 *      EvalPlanQualSlot() for this rel, for increased efficiency.
 *
 * This tests whether the tuple in inputslot still matches the relevant
 * quals. For that result to be useful, typically the input tuple has to be
 * last row version (otherwise the result isn't particularly useful) and
 * locked (otherwise the result might be out of date). That's typically
 * achieved by using table_tuple_lock() with the
 * TUPLE_LOCK_FLAG_FIND_LAST_VERSION flag.
 *
 * Returns a slot containing the new candidate update/delete tuple, or
 * NULL if we determine we shouldn't process the row.
 */
TupleTableSlot *
EvalPlanQual(EPQState *epqstate, Relation relation,
             Index rti, TupleTableSlot *inputslot)
{
    TupleTableSlot *slot;
    TupleTableSlot *testslot;
 
    Assert(rti > 0);
 
    /*
     * Need to run a recheck subquery.  Initialize or reinitialize EPQ state.
     */
    EvalPlanQualBegin(epqstate);
 
    /*
     * Callers will often use the EvalPlanQualSlot to store the tuple to avoid
     * an unnecessary copy.
     */
    testslot = EvalPlanQualSlot(epqstate, relation, rti);
    if (testslot != inputslot)
        ExecCopySlot(testslot, inputslot);
 
    /*
     * Mark that an EPQ tuple is available for this relation.  (If there is
     * more than one result relation, the others remain marked as having no
     * tuple available.)
     */
    epqstate->relsubs_done[rti - 1] = false;
    epqstate->relsubs_blocked[rti - 1] = false;
 
    /*
     * 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))
        ExecMaterializeSlot(slot);
 
    /*
     * Clear out the test tuple, and mark that no tuple is available here.
     * This is needed in case the EPQ state is re-used to test a tuple for a
     * different target relation.
     */
    ExecClearTuple(testslot);
    epqstate->relsubs_blocked[rti - 1] = true;
 
    return slot;
}
 
/*
 * EvalPlanQualInit -- initialize during creation of a plan state node
 * that might need to invoke EPQ processing.
 *
 * If the caller intends to use EvalPlanQual(), resultRelations should be
 * a list of RT indexes of potential target relations for EvalPlanQual(),
 * and we will arrange that the other listed relations don't return any
 * tuple during an EvalPlanQual() call.  Otherwise resultRelations
 * should be NIL.
 *
 * Note: subplan/auxrowmarks can be NULL/NIL if they will be set later
 * with EvalPlanQualSetPlan.
 */
void
EvalPlanQualInit(EPQState *epqstate, EState *parentestate,
                 Plan *subplan, List *auxrowmarks,
                 int epqParam, List *resultRelations)
{
    Index       rtsize = parentestate->es_range_table_size;
 
    /* initialize data not changing over EPQState's lifetime */
    epqstate->parentestate = parentestate;
    epqstate->epqParam = epqParam;
    epqstate->resultRelations = resultRelations;
 
    /*
     * Allocate space to reference a slot for each potential rti - do so now
     * rather than in EvalPlanQualBegin(), as done for other dynamically
     * allocated resources, so EvalPlanQualSlot() can be used to hold tuples
     * that *may* need EPQ later, without forcing the overhead of
     * EvalPlanQualBegin().
     */
    epqstate->tuple_table = NIL;
    epqstate->relsubs_slot = (TupleTableSlot **)
        palloc0(rtsize * sizeof(TupleTableSlot *));
 
    /* ... and remember data that EvalPlanQualBegin will need */
    epqstate->plan = subplan;
    epqstate->arowMarks = auxrowmarks;
 
    /* ... and mark the EPQ state inactive */
    epqstate->origslot = NULL;
    epqstate->recheckestate = NULL;
    epqstate->recheckplanstate = NULL;
    epqstate->relsubs_rowmark = NULL;
    epqstate->relsubs_done = NULL;
    epqstate->relsubs_blocked = NULL;
}
 
/*
 * EvalPlanQualSetPlan -- set or change subplan of an EPQState.
 *
 * We used to need this so that ModifyTable could deal with multiple subplans.
 * It could now be refactored out of existence.
 */
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;
}
 
/*
 * Return, and create if necessary, a slot for an EPQ test tuple.
 *
 * Note this only requires EvalPlanQualInit() to have been called,
 * EvalPlanQualBegin() is not necessary.
 */
TupleTableSlot *
EvalPlanQualSlot(EPQState *epqstate,
                 Relation relation, Index rti)
{
    TupleTableSlot **slot;
 
    Assert(relation);
    Assert(rti > 0 && rti <= epqstate->parentestate->es_range_table_size);
    slot = &epqstate->relsubs_slot[rti - 1];
 
    if (*slot == NULL)
    {
        MemoryContext oldcontext;
 
        oldcontext = MemoryContextSwitchTo(epqstate->parentestate->es_query_cxt);
        *slot = table_slot_create(relation, &epqstate->tuple_table);
        MemoryContextSwitchTo(oldcontext);
    }
 
    return *slot;
}
 
/*
 * Fetch the current row value for a non-locked relation, identified by rti,
 * that needs 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.  Returns true if a substitution tuple was found, false if not.
 */
bool
EvalPlanQualFetchRowMark(EPQState *epqstate, Index rti, TupleTableSlot *slot)
{
    ExecAuxRowMark *earm = epqstate->relsubs_rowmark[rti - 1];
    ExecRowMark *erm;
    Datum       datum;
    bool        isNull;
 
    Assert(earm != NULL);
    Assert(epqstate->origslot != NULL);
 
    erm = earm->rowmark;
 
    if (RowMarkRequiresRowShareLock(erm->markType))
        elog(ERROR, "EvalPlanQual doesn't support locking rowmarks");
 
    /* if child rel, must check whether it produced this row */
    if (erm->rti != erm->prti)
    {
        Oid         tableoid;
 
        datum = ExecGetJunkAttribute(epqstate->origslot,
                                     earm->toidAttNo,
                                     &isNull);
        /* non-locked rels could be on the inside of outer joins */
        if (isNull)
            return false;
 
        tableoid = DatumGetObjectId(datum);
 
        Assert(OidIsValid(erm->relid));
        if (tableoid != erm->relid)
        {
            /* this child is inactive right now */
            return false;
        }
    }
 
    if (erm->markType == ROW_MARK_REFERENCE)
    {
        Assert(erm->relation != NULL);
 
        /* fetch the tuple's ctid */
        datum = ExecGetJunkAttribute(epqstate->origslot,
                                     earm->ctidAttNo,
                                     &isNull);
        /* non-locked rels could be on the inside of outer joins */
        if (isNull)
            return false;
 
        /* 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))));
 
            fdwroutine->RefetchForeignRow(epqstate->recheckestate,
                                          erm,
                                          datum,
                                          slot,
                                          &updated);
            if (TupIsNull(slot))
                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.
             */
            return true;
        }
        else
        {
            /* ordinary table, fetch the tuple */
            if (!table_tuple_fetch_row_version(erm->relation,
                                               (ItemPointer) DatumGetPointer(datum),
                                               SnapshotAny, slot))
                elog(ERROR, "failed to fetch tuple for EvalPlanQual recheck");
            return true;
        }
    }
    else
    {
        Assert(erm->markType == ROW_MARK_COPY);
 
        /* fetch the whole-row Var for the relation */
        datum = ExecGetJunkAttribute(epqstate->origslot,
                                     earm->wholeAttNo,
                                     &isNull);
        /* non-locked rels could be on the inside of outer joins */
        if (isNull)
            return false;
 
        ExecStoreHeapTupleDatum(datum, slot);
        return true;
    }
}
 
/*
 * 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->recheckestate->es_query_cxt);
    slot = ExecProcNode(epqstate->recheckplanstate);
    MemoryContextSwitchTo(oldcontext);
 
    return slot;
}
 
/*
 * Initialize or reset an EvalPlanQual state tree
 */
void
EvalPlanQualBegin(EPQState *epqstate)
{
    EState     *parentestate = epqstate->parentestate;
    EState     *recheckestate = epqstate->recheckestate;
 
    if (recheckestate == NULL)
    {
        /* First time through, so create a child EState */
        EvalPlanQualStart(epqstate, epqstate->plan);
    }
    else
    {
        /*
         * We already have a suitable child EPQ tree, so just reset it.
         */
        Index       rtsize = parentestate->es_range_table_size;
        PlanState  *rcplanstate = epqstate->recheckplanstate;
 
        /*
         * Reset the relsubs_done[] flags to equal relsubs_blocked[], so that
         * the EPQ run will never attempt to fetch tuples from blocked target
         * relations.
         */
        memcpy(epqstate->relsubs_done, epqstate->relsubs_blocked,
               rtsize * sizeof(bool));
 
        /* Recopy current values of parent parameters */
        if (parentestate->es_plannedstmt->paramExecTypes != NIL)
        {
            int         i;
 
            /*
             * Force evaluation of any InitPlan outputs that could be needed
             * by the subplan, just in case they got reset since
             * EvalPlanQualStart (see comments therein).
             */
            ExecSetParamPlanMulti(rcplanstate->plan->extParam,
                                  GetPerTupleExprContext(parentestate));
 
            i = list_length(parentestate->es_plannedstmt->paramExecTypes);
 
            while (--i >= 0)
            {
                /* copy value if any, but not execPlan link */
                recheckestate->es_param_exec_vals[i].value =
                    parentestate->es_param_exec_vals[i].value;
                recheckestate->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.
         */
        rcplanstate->chgParam = bms_add_member(rcplanstate->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, Plan *planTree)
{
    EState     *parentestate = epqstate->parentestate;
    Index       rtsize = parentestate->es_range_table_size;
    EState     *rcestate;
    MemoryContext oldcontext;
    ListCell   *l;
 
    epqstate->recheckestate = rcestate = CreateExecutorState();
 
    oldcontext = MemoryContextSwitchTo(rcestate->es_query_cxt);
 
    /* signal that this is an EState for executing EPQ */
    rcestate->es_epq_active = epqstate;
 
    /*
     * Child EPQ EStates share the parent's copy of unchanging state such as
     * the snapshot, rangetable, and external Param info.  They need their own
     * copies of local state, including a tuple table, es_param_exec_vals,
     * result-rel info, etc.
     */
    rcestate->es_direction = ForwardScanDirection;
    rcestate->es_snapshot = parentestate->es_snapshot;
    rcestate->es_crosscheck_snapshot = parentestate->es_crosscheck_snapshot;
    rcestate->es_range_table = parentestate->es_range_table;
    rcestate->es_range_table_size = parentestate->es_range_table_size;
    rcestate->es_relations = parentestate->es_relations;
    rcestate->es_rowmarks = parentestate->es_rowmarks;
    rcestate->es_rteperminfos = parentestate->es_rteperminfos;
    rcestate->es_plannedstmt = parentestate->es_plannedstmt;
    rcestate->es_junkFilter = parentestate->es_junkFilter;
    rcestate->es_output_cid = parentestate->es_output_cid;
    rcestate->es_queryEnv = parentestate->es_queryEnv;
 
    /*
     * ResultRelInfos needed by subplans are initialized from scratch when the
     * subplans themselves are initialized.
     */
    rcestate->es_result_relations = NULL;
    /* es_trig_target_relations must NOT be copied */
    rcestate->es_top_eflags = parentestate->es_top_eflags;
    rcestate->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.
     */
    rcestate->es_param_list_info = parentestate->es_param_list_info;
    if (parentestate->es_plannedstmt->paramExecTypes != NIL)
    {
        int         i;
 
        /*
         * Force evaluation of any InitPlan outputs that could be needed by
         * the subplan.  (With more complexity, maybe we could postpone this
         * till the subplan actually demands them, but it doesn't seem worth
         * the trouble; this is a corner case already, since usually the
         * InitPlans would have been evaluated before reaching EvalPlanQual.)
         *
         * This will not touch output params of InitPlans that occur somewhere
         * within the subplan tree, only those that are attached to the
         * ModifyTable node or above it and are referenced within the subplan.
         * That's OK though, because the planner would only attach such
         * InitPlans to a lower-level SubqueryScan node, and EPQ execution
         * will not descend into a SubqueryScan.
         *
         * The EState's per-output-tuple econtext is sufficiently short-lived
         * for this, since it should get reset before there is any chance of
         * doing EvalPlanQual again.
         */
        ExecSetParamPlanMulti(planTree->extParam,
                              GetPerTupleExprContext(parentestate));
 
        /* now make the internal param workspace ... */
        i = list_length(parentestate->es_plannedstmt->paramExecTypes);
        rcestate->es_param_exec_vals = (ParamExecData *)
            palloc0(i * sizeof(ParamExecData));
        /* ... and copy down all values, whether really needed or not */
        while (--i >= 0)
        {
            /* copy value if any, but not execPlan link */
            rcestate->es_param_exec_vals[i].value =
                parentestate->es_param_exec_vals[i].value;
            rcestate->es_param_exec_vals[i].isnull =
                parentestate->es_param_exec_vals[i].isnull;
        }
    }
 
    /*
     * Copy es_unpruned_relids so that pruned relations are ignored by
     * ExecInitLockRows() and ExecInitModifyTable() when initializing the plan
     * trees below.
     */
    rcestate->es_unpruned_relids = parentestate->es_unpruned_relids;
 
    /*
     * 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(rcestate->es_subplanstates == NIL);
    foreach(l, parentestate->es_plannedstmt->subplans)
    {
        Plan       *subplan = (Plan *) lfirst(l);
        PlanState  *subplanstate;
 
        subplanstate = ExecInitNode(subplan, rcestate, 0);
        rcestate->es_subplanstates = lappend(rcestate->es_subplanstates,
                                             subplanstate);
    }
 
    /*
     * Build an RTI indexed array of rowmarks, so that
     * EvalPlanQualFetchRowMark() can efficiently access the to be fetched
     * rowmark.
     */
    epqstate->relsubs_rowmark = (ExecAuxRowMark **)
        palloc0(rtsize * sizeof(ExecAuxRowMark *));
    foreach(l, epqstate->arowMarks)
    {
        ExecAuxRowMark *earm = (ExecAuxRowMark *) lfirst(l);
 
        epqstate->relsubs_rowmark[earm->rowmark->rti - 1] = earm;
    }
 
    /*
     * Initialize per-relation EPQ tuple states.  Result relations, if any,
     * get marked as blocked; others as not-fetched.
     */
    epqstate->relsubs_done = palloc_array(bool, rtsize);
    epqstate->relsubs_blocked = palloc0_array(bool, rtsize);
 
    foreach(l, epqstate->resultRelations)
    {
        int         rtindex = lfirst_int(l);
 
        Assert(rtindex > 0 && rtindex <= rtsize);
        epqstate->relsubs_blocked[rtindex - 1] = true;
    }
 
    memcpy(epqstate->relsubs_done, epqstate->relsubs_blocked,
           rtsize * sizeof(bool));
 
    /*
     * 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->recheckplanstate = ExecInitNode(planTree, rcestate, 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
 * result and 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->recheckestate;
    Index       rtsize;
    MemoryContext oldcontext;
    ListCell   *l;
 
    rtsize = epqstate->parentestate->es_range_table_size;
 
    /*
     * We may have a tuple table, even if EPQ wasn't started, because we allow
     * use of EvalPlanQualSlot() without calling EvalPlanQualBegin().
     */
    if (epqstate->tuple_table != NIL)
    {
        memset(epqstate->relsubs_slot, 0,
               rtsize * sizeof(TupleTableSlot *));
        ExecResetTupleTable(epqstate->tuple_table, true);
        epqstate->tuple_table = NIL;
    }
 
    /* EPQ wasn't started, nothing further to do */
    if (estate == NULL)
        return;
 
    oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 
    ExecEndNode(epqstate->recheckplanstate);
 
    foreach(l, estate->es_subplanstates)
    {
        PlanState  *subplanstate = (PlanState *) lfirst(l);
 
        ExecEndNode(subplanstate);
    }
 
    /* throw away the per-estate tuple table, some node may have used it */
    ExecResetTupleTable(estate->es_tupleTable, false);
 
    /* Close any result and trigger target relations attached to this EState */
    ExecCloseResultRelations(estate);
 
    MemoryContextSwitchTo(oldcontext);
 
    FreeExecutorState(estate);
 
    /* Mark EPQState idle */
    epqstate->origslot = NULL;
    epqstate->recheckestate = NULL;
    epqstate->recheckplanstate = NULL;
    epqstate->relsubs_rowmark = NULL;
    epqstate->relsubs_done = NULL;
    epqstate->relsubs_blocked = NULL;
}