execPartition.c

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/*-------------------------------------------------------------------------
 *
 * execPartition.c
 *    Support routines for partitioning.
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/executor/execPartition.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/table.h"
#include "access/tableam.h"
#include "catalog/partition.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_type.h"
#include "executor/execPartition.h"
#include "executor/executor.h"
#include "foreign/fdwapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "partitioning/partbounds.h"
#include "partitioning/partdesc.h"
#include "partitioning/partprune.h"
#include "rewrite/rewriteManip.h"
#include "utils/acl.h"
#include "utils/lsyscache.h"
#include "utils/partcache.h"
#include "utils/rls.h"
#include "utils/ruleutils.h"


/*-----------------------
 * PartitionTupleRouting - Encapsulates all information required to
 * route a tuple inserted into a partitioned table to one of its leaf
 * partitions.
 *
 * partition_root
 *      The partitioned table that's the target of the command.
 *
 * partition_dispatch_info
 *      Array of 'max_dispatch' elements containing a pointer to a
 *      PartitionDispatch object for every partitioned table touched by tuple
 *      routing.  The entry for the target partitioned table is *always*
 *      present in the 0th element of this array.  See comment for
 *      PartitionDispatchData->indexes for details on how this array is
 *      indexed.
 *
 * nonleaf_partitions
 *      Array of 'max_dispatch' elements containing pointers to fake
 *      ResultRelInfo objects for nonleaf partitions, useful for checking
 *      the partition constraint.
 *
 * num_dispatch
 *      The current number of items stored in the 'partition_dispatch_info'
 *      array.  Also serves as the index of the next free array element for
 *      new PartitionDispatch objects that need to be stored.
 *
 * max_dispatch
 *      The current allocated size of the 'partition_dispatch_info' array.
 *
 * partitions
 *      Array of 'max_partitions' elements containing a pointer to a
 *      ResultRelInfo for every leaf partitions touched by tuple routing.
 *      Some of these are pointers to ResultRelInfos which are borrowed out of
 *      'subplan_resultrel_htab'.  The remainder have been built especially
 *      for tuple routing.  See comment for PartitionDispatchData->indexes for
 *      details on how this array is indexed.
 *
 * num_partitions
 *      The current number of items stored in the 'partitions' array.  Also
 *      serves as the index of the next free array element for new
 *      ResultRelInfo objects that need to be stored.
 *
 * max_partitions
 *      The current allocated size of the 'partitions' array.
 *
 * subplan_resultrel_htab
 *      Hash table to store subplan ResultRelInfos by Oid.  This is used to
 *      cache ResultRelInfos from subplans of an UPDATE ModifyTable node;
 *      NULL in other cases.  Some of these may be useful for tuple routing
 *      to save having to build duplicates.
 *
 * memcxt
 *      Memory context used to allocate subsidiary structs.
 *-----------------------
 */
struct PartitionTupleRouting
{
    Relation    partition_root;
    PartitionDispatch *partition_dispatch_info;
    ResultRelInfo **nonleaf_partitions;
    int         num_dispatch;
    int         max_dispatch;
    ResultRelInfo **partitions;
    int         num_partitions;
    int         max_partitions;
    HTAB       *subplan_resultrel_htab;
    MemoryContext memcxt;
};

/*-----------------------
 * PartitionDispatch - information about one partitioned table in a partition
 * hierarchy required to route a tuple to any of its partitions.  A
 * PartitionDispatch is always encapsulated inside a PartitionTupleRouting
 * struct and stored inside its 'partition_dispatch_info' array.
 *
 * reldesc
 *      Relation descriptor of the table
 *
 * key
 *      Partition key information of the table
 *
 * keystate
 *      Execution state required for expressions in the partition key
 *
 * partdesc
 *      Partition descriptor of the table
 *
 * tupslot
 *      A standalone TupleTableSlot initialized with this table's tuple
 *      descriptor, or NULL if no tuple conversion between the parent is
 *      required.
 *
 * tupmap
 *      TupleConversionMap to convert from the parent's rowtype to this table's
 *      rowtype  (when extracting the partition key of a tuple just before
 *      routing it through this table). A NULL value is stored if no tuple
 *      conversion is required.
 *
 * indexes
 *      Array of partdesc->nparts elements.  For leaf partitions the index
 *      corresponds to the partition's ResultRelInfo in the encapsulating
 *      PartitionTupleRouting's partitions array.  For partitioned partitions,
 *      the index corresponds to the PartitionDispatch for it in its
 *      partition_dispatch_info array.  -1 indicates we've not yet allocated
 *      anything in PartitionTupleRouting for the partition.
 *-----------------------
 */
typedef struct PartitionDispatchData
{
    Relation    reldesc;
    PartitionKey key;
    List       *keystate;       /* list of ExprState */
    PartitionDesc partdesc;
    TupleTableSlot *tupslot;
    AttrMap    *tupmap;
    int         indexes[FLEXIBLE_ARRAY_MEMBER];
}           PartitionDispatchData;

/* struct to hold result relations coming from UPDATE subplans */
typedef struct SubplanResultRelHashElem
{
    Oid         relid;          /* hash key -- must be first */
    ResultRelInfo *rri;
} SubplanResultRelHashElem;


static void ExecHashSubPlanResultRelsByOid(ModifyTableState *mtstate,
                                           PartitionTupleRouting *proute);
static ResultRelInfo *ExecInitPartitionInfo(ModifyTableState *mtstate,
                                            EState *estate, PartitionTupleRouting *proute,
                                            PartitionDispatch dispatch,
                                            ResultRelInfo *rootResultRelInfo,
                                            int partidx);
static void ExecInitRoutingInfo(ModifyTableState *mtstate,
                                EState *estate,
                                PartitionTupleRouting *proute,
                                PartitionDispatch dispatch,
                                ResultRelInfo *partRelInfo,
                                int partidx);
static PartitionDispatch ExecInitPartitionDispatchInfo(EState *estate,
                                                       PartitionTupleRouting *proute,
                                                       Oid partoid, PartitionDispatch parent_pd,
                                                       int partidx, ResultRelInfo *rootResultRelInfo);
static void FormPartitionKeyDatum(PartitionDispatch pd,
                                  TupleTableSlot *slot,
                                  EState *estate,
                                  Datum *values,
                                  bool *isnull);
static int  get_partition_for_tuple(PartitionDispatch pd, Datum *values,
                                    bool *isnull);
static char *ExecBuildSlotPartitionKeyDescription(Relation rel,
                                                  Datum *values,
                                                  bool *isnull,
                                                  int maxfieldlen);
static List *adjust_partition_tlist(List *tlist, TupleConversionMap *map);
static void ExecInitPruningContext(PartitionPruneContext *context,
                                   List *pruning_steps,
                                   PartitionDesc partdesc,
                                   PartitionKey partkey,
                                   PlanState *planstate);
static void find_matching_subplans_recurse(PartitionPruningData *prunedata,
                                           PartitionedRelPruningData *pprune,
                                           bool initial_prune,
                                           Bitmapset **validsubplans);


/*
 * ExecSetupPartitionTupleRouting - sets up information needed during
 * tuple routing for partitioned tables, encapsulates it in
 * PartitionTupleRouting, and returns it.
 *
 * Callers must use the returned PartitionTupleRouting during calls to
 * ExecFindPartition().  The actual ResultRelInfo for a partition is only
 * allocated when the partition is found for the first time.
 *
 * The current memory context is used to allocate this struct and all
 * subsidiary structs that will be allocated from it later on.  Typically
 * it should be estate->es_query_cxt.
 */
PartitionTupleRouting *
ExecSetupPartitionTupleRouting(EState *estate, ModifyTableState *mtstate,
                               Relation rel)
{
    PartitionTupleRouting *proute;
    ModifyTable *node = mtstate ? (ModifyTable *) mtstate->ps.plan : NULL;

    /*
     * Here we attempt to expend as little effort as possible in setting up
     * the PartitionTupleRouting.  Each partition's ResultRelInfo is built on
     * demand, only when we actually need to route a tuple to that partition.
     * The reason for this is that a common case is for INSERT to insert a
     * single tuple into a partitioned table and this must be fast.
     */
    proute = (PartitionTupleRouting *) palloc0(sizeof(PartitionTupleRouting));
    proute->partition_root = rel;
    proute->memcxt = CurrentMemoryContext;
    /* Rest of members initialized by zeroing */

    /*
     * Initialize this table's PartitionDispatch object.  Here we pass in the
     * parent as NULL as we don't need to care about any parent of the target
     * partitioned table.
     */
    ExecInitPartitionDispatchInfo(estate, proute, RelationGetRelid(rel),
                                  NULL, 0, NULL);

    /*
     * If performing an UPDATE with tuple routing, we can reuse partition
     * sub-plan result rels.  We build a hash table to map the OIDs of
     * partitions present in mtstate->resultRelInfo to their ResultRelInfos.
     * Every time a tuple is routed to a partition that we've yet to set the
     * ResultRelInfo for, before we go to the trouble of making one, we check
     * for a pre-made one in the hash table.
     */
    if (node && node->operation == CMD_UPDATE)
        ExecHashSubPlanResultRelsByOid(mtstate, proute);

    return proute;
}

/*
 * ExecFindPartition -- Return the ResultRelInfo for the leaf partition that
 * the tuple contained in *slot should belong to.
 *
 * If the partition's ResultRelInfo does not yet exist in 'proute' then we set
 * one up or reuse one from mtstate's resultRelInfo array.  When reusing a
 * ResultRelInfo from the mtstate we verify that the relation is a valid
 * target for INSERTs and initialize tuple routing information.
 *
 * rootResultRelInfo is the relation named in the query.
 *
 * estate must be non-NULL; we'll need it to compute any expressions in the
 * partition keys.  Also, its per-tuple contexts are used as evaluation
 * scratch space.
 *
 * If no leaf partition is found, this routine errors out with the appropriate
 * error message.  An error may also be raised if the found target partition
 * is not a valid target for an INSERT.
 */
ResultRelInfo *
ExecFindPartition(ModifyTableState *mtstate,
                  ResultRelInfo *rootResultRelInfo,
                  PartitionTupleRouting *proute,
                  TupleTableSlot *slot, EState *estate)
{
    PartitionDispatch *pd = proute->partition_dispatch_info;
    Datum       values[PARTITION_MAX_KEYS];
    bool        isnull[PARTITION_MAX_KEYS];
    Relation    rel;
    PartitionDispatch dispatch;
    PartitionDesc partdesc;
    ExprContext *ecxt = GetPerTupleExprContext(estate);
    TupleTableSlot *ecxt_scantuple_saved = ecxt->ecxt_scantuple;
    TupleTableSlot *rootslot = slot;
    TupleTableSlot *myslot = NULL;
    MemoryContext oldcxt;
    ResultRelInfo *rri = NULL;

    /* use per-tuple context here to avoid leaking memory */
    oldcxt = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));

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

    /* start with the root partitioned table */
    dispatch = pd[0];
    while (dispatch != NULL)
    {
        int         partidx = -1;
        bool        is_leaf;

        CHECK_FOR_INTERRUPTS();

        rel = dispatch->reldesc;
        partdesc = dispatch->partdesc;

        /*
         * Extract partition key from tuple. Expression evaluation machinery
         * that FormPartitionKeyDatum() invokes expects ecxt_scantuple to
         * point to the correct tuple slot.  The slot might have changed from
         * what was used for the parent table if the table of the current
         * partitioning level has different tuple descriptor from the parent.
         * So update ecxt_scantuple accordingly.
         */
        ecxt->ecxt_scantuple = slot;
        FormPartitionKeyDatum(dispatch, slot, estate, values, isnull);

        /*
         * If this partitioned table has no partitions or no partition for
         * these values, error out.
         */
        if (partdesc->nparts == 0 ||
            (partidx = get_partition_for_tuple(dispatch, values, isnull)) < 0)
        {
            char       *val_desc;

            val_desc = ExecBuildSlotPartitionKeyDescription(rel,
                                                            values, isnull, 64);
            Assert(OidIsValid(RelationGetRelid(rel)));
            ereport(ERROR,
                    (errcode(ERRCODE_CHECK_VIOLATION),
                     errmsg("no partition of relation \"%s\" found for row",
                            RelationGetRelationName(rel)),
                     val_desc ?
                     errdetail("Partition key of the failing row contains %s.",
                               val_desc) : 0,
                     errtable(rel)));
        }

        is_leaf = partdesc->is_leaf[partidx];
        if (is_leaf)
        {

            /*
             * We've reached the leaf -- hurray, we're done.  Look to see if
             * we've already got a ResultRelInfo for this partition.
             */
            if (likely(dispatch->indexes[partidx] >= 0))
            {
                /* ResultRelInfo already built */
                Assert(dispatch->indexes[partidx] < proute->num_partitions);
                rri = proute->partitions[dispatch->indexes[partidx]];
            }
            else
            {
                bool        found = false;

                /*
                 * We have not yet set up a ResultRelInfo for this partition,
                 * but if we have a subplan hash table, we might have one
                 * there.  If not, we'll have to create one.
                 */
                if (proute->subplan_resultrel_htab)
                {
                    Oid         partoid = partdesc->oids[partidx];
                    SubplanResultRelHashElem *elem;

                    elem = hash_search(proute->subplan_resultrel_htab,
                                       &partoid, HASH_FIND, NULL);
                    if (elem)
                    {
                        found = true;
                        rri = elem->rri;

                        /* Verify this ResultRelInfo allows INSERTs */
                        CheckValidResultRel(rri, CMD_INSERT);

                        /*
                         * Initialize information needed to insert this and
                         * subsequent tuples routed to this partition.
                         */
                        ExecInitRoutingInfo(mtstate, estate, proute, dispatch,
                                            rri, partidx);
                    }
                }

                /* We need to create a new one. */
                if (!found)
                    rri = ExecInitPartitionInfo(mtstate, estate, proute,
                                                dispatch,
                                                rootResultRelInfo, partidx);
            }
            Assert(rri != NULL);

            /* Signal to terminate the loop */
            dispatch = NULL;
        }
        else
        {
            /*
             * Partition is a sub-partitioned table; get the PartitionDispatch
             */
            if (likely(dispatch->indexes[partidx] >= 0))
            {
                /* Already built. */
                Assert(dispatch->indexes[partidx] < proute->num_dispatch);

                rri = proute->nonleaf_partitions[dispatch->indexes[partidx]];

                /*
                 * Move down to the next partition level and search again
                 * until we find a leaf partition that matches this tuple
                 */
                dispatch = pd[dispatch->indexes[partidx]];
            }
            else
            {
                /* Not yet built. Do that now. */
                PartitionDispatch subdispatch;

                /*
                 * Create the new PartitionDispatch.  We pass the current one
                 * in as the parent PartitionDispatch
                 */
                subdispatch = ExecInitPartitionDispatchInfo(estate,
                                                            proute,
                                                            partdesc->oids[partidx],
                                                            dispatch, partidx,
                                                            mtstate->rootResultRelInfo);
                Assert(dispatch->indexes[partidx] >= 0 &&
                       dispatch->indexes[partidx] < proute->num_dispatch);

                rri = proute->nonleaf_partitions[dispatch->indexes[partidx]];
                dispatch = subdispatch;
            }

            /*
             * Convert the tuple to the new parent's layout, if different from
             * the previous parent.
             */
            if (dispatch->tupslot)
            {
                AttrMap    *map = dispatch->tupmap;
                TupleTableSlot *tempslot = myslot;

                myslot = dispatch->tupslot;
                slot = execute_attr_map_slot(map, slot, myslot);

                if (tempslot != NULL)
                    ExecClearTuple(tempslot);
            }
        }

        /*
         * If this partition is the default one, we must check its partition
         * constraint now, which may have changed concurrently due to
         * partitions being added to the parent.
         *
         * (We do this here, and do not rely on ExecInsert doing it, because
         * we don't want to miss doing it for non-leaf partitions.)
         */
        if (partidx == partdesc->boundinfo->default_index)
        {
            /*
             * The tuple must match the partition's layout for the constraint
             * expression to be evaluated successfully.  If the partition is
             * sub-partitioned, that would already be the case due to the code
             * above, but for a leaf partition the tuple still matches the
             * parent's layout.
             *
             * Note that we have a map to convert from root to current
             * partition, but not from immediate parent to current partition.
             * So if we have to convert, do it from the root slot; if not, use
             * the root slot as-is.
             */
            if (is_leaf)
            {
                TupleConversionMap *map = rri->ri_RootToPartitionMap;

                if (map)
                    slot = execute_attr_map_slot(map->attrMap, rootslot,
                                                 rri->ri_PartitionTupleSlot);
                else
                    slot = rootslot;
            }

            ExecPartitionCheck(rri, slot, estate, true);
        }
    }

    /* Release the tuple in the lowest parent's dedicated slot. */
    if (myslot != NULL)
        ExecClearTuple(myslot);
    /* and restore ecxt's scantuple */
    ecxt->ecxt_scantuple = ecxt_scantuple_saved;
    MemoryContextSwitchTo(oldcxt);

    return rri;
}

/*
 * ExecHashSubPlanResultRelsByOid
 *      Build a hash table to allow fast lookups of subplan ResultRelInfos by
 *      partition Oid.  We also populate the subplan ResultRelInfo with an
 *      ri_PartitionRoot.
 */
static void
ExecHashSubPlanResultRelsByOid(ModifyTableState *mtstate,
                               PartitionTupleRouting *proute)
{
    HASHCTL     ctl;
    HTAB       *htab;
    int         i;

    ctl.keysize = sizeof(Oid);
    ctl.entrysize = sizeof(SubplanResultRelHashElem);
    ctl.hcxt = CurrentMemoryContext;

    htab = hash_create("PartitionTupleRouting table", mtstate->mt_nplans,
                       &ctl, HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
    proute->subplan_resultrel_htab = htab;

    /* Hash all subplans by their Oid */
    for (i = 0; i < mtstate->mt_nplans; i++)
    {
        ResultRelInfo *rri = &mtstate->resultRelInfo[i];
        bool        found;
        Oid         partoid = RelationGetRelid(rri->ri_RelationDesc);
        SubplanResultRelHashElem *elem;

        elem = (SubplanResultRelHashElem *)
            hash_search(htab, &partoid, HASH_ENTER, &found);
        Assert(!found);
        elem->rri = rri;

        /*
         * This is required in order to convert the partition's tuple to be
         * compatible with the root partitioned table's tuple descriptor. When
         * generating the per-subplan result rels, this was not set.
         */
        rri->ri_RootResultRelInfo = mtstate->rootResultRelInfo;
    }
}

/*
 * ExecInitPartitionInfo
 *      Lock the partition and initialize ResultRelInfo.  Also setup other
 *      information for the partition and store it in the next empty slot in
 *      the proute->partitions array.
 *
 * Returns the ResultRelInfo
 */
static ResultRelInfo *
ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
                      PartitionTupleRouting *proute,
                      PartitionDispatch dispatch,
                      ResultRelInfo *rootResultRelInfo,
                      int partidx)
{
    ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
    Relation    partrel;
    int         firstVarno = mtstate->resultRelInfo[0].ri_RangeTableIndex;
    Relation    firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
    ResultRelInfo *leaf_part_rri;
    MemoryContext oldcxt;
    AttrMap    *part_attmap = NULL;
    bool        found_whole_row;

    oldcxt = MemoryContextSwitchTo(proute->memcxt);

    partrel = table_open(dispatch->partdesc->oids[partidx], RowExclusiveLock);

    leaf_part_rri = makeNode(ResultRelInfo);
    InitResultRelInfo(leaf_part_rri,
                      partrel,
                      0,
                      rootResultRelInfo,
                      estate->es_instrument);

    /*
     * Verify result relation is a valid target for an INSERT.  An UPDATE of a
     * partition-key becomes a DELETE+INSERT operation, so this check is still
     * required when the operation is CMD_UPDATE.
     */
    CheckValidResultRel(leaf_part_rri, CMD_INSERT);

    /*
     * Open partition indices.  The user may have asked to check for conflicts
     * within this leaf partition and do "nothing" instead of throwing an
     * error.  Be prepared in that case by initializing the index information
     * needed by ExecInsert() to perform speculative insertions.
     */
    if (partrel->rd_rel->relhasindex &&
        leaf_part_rri->ri_IndexRelationDescs == NULL)
        ExecOpenIndices(leaf_part_rri,
                        (node != NULL &&
                         node->onConflictAction != ONCONFLICT_NONE));

    /*
     * Build WITH CHECK OPTION constraints for the partition.  Note that we
     * didn't build the withCheckOptionList for partitions within the planner,
     * but simple translation of varattnos will suffice.  This only occurs for
     * the INSERT case or in the case of UPDATE tuple routing where we didn't
     * find a result rel to reuse in ExecSetupPartitionTupleRouting().
     */
    if (node && node->withCheckOptionLists != NIL)
    {
        List       *wcoList;
        List       *wcoExprs = NIL;
        ListCell   *ll;

        /*
         * In the case of INSERT on a partitioned table, there is only one
         * plan.  Likewise, there is only one WCO list, not one per partition.
         * For UPDATE, there are as many WCO lists as there are plans.
         */
        Assert((node->operation == CMD_INSERT &&
                list_length(node->withCheckOptionLists) == 1 &&
                list_length(node->plans) == 1) ||
               (node->operation == CMD_UPDATE &&
                list_length(node->withCheckOptionLists) ==
                list_length(node->plans)));

        /*
         * Use the WCO list of the first plan as a reference to calculate
         * attno's for the WCO list of this partition.  In the INSERT case,
         * that refers to the root partitioned table, whereas in the UPDATE
         * tuple routing case, that refers to the first partition in the
         * mtstate->resultRelInfo array.  In any case, both that relation and
         * this partition should have the same columns, so we should be able
         * to map attributes successfully.
         */
        wcoList = linitial(node->withCheckOptionLists);

        /*
         * Convert Vars in it to contain this partition's attribute numbers.
         */
        part_attmap =
            build_attrmap_by_name(RelationGetDescr(partrel),
                                  RelationGetDescr(firstResultRel));
        wcoList = (List *)
            map_variable_attnos((Node *) wcoList,
                                firstVarno, 0,
                                part_attmap,
                                RelationGetForm(partrel)->reltype,
                                &found_whole_row);
        /* We ignore the value of found_whole_row. */

        foreach(ll, wcoList)
        {
            WithCheckOption *wco = castNode(WithCheckOption, lfirst(ll));
            ExprState  *wcoExpr = ExecInitQual(castNode(List, wco->qual),
                                               &mtstate->ps);

            wcoExprs = lappend(wcoExprs, wcoExpr);
        }

        leaf_part_rri->ri_WithCheckOptions = wcoList;
        leaf_part_rri->ri_WithCheckOptionExprs = wcoExprs;
    }

    /*
     * Build the RETURNING projection for the partition.  Note that we didn't
     * build the returningList for partitions within the planner, but simple
     * translation of varattnos will suffice.  This only occurs for the INSERT
     * case or in the case of UPDATE tuple routing where we didn't find a
     * result rel to reuse in ExecSetupPartitionTupleRouting().
     */
    if (node && node->returningLists != NIL)
    {
        TupleTableSlot *slot;
        ExprContext *econtext;
        List       *returningList;

        /* See the comment above for WCO lists. */
        Assert((node->operation == CMD_INSERT &&
                list_length(node->returningLists) == 1 &&
                list_length(node->plans) == 1) ||
               (node->operation == CMD_UPDATE &&
                list_length(node->returningLists) ==
                list_length(node->plans)));

        /*
         * Use the RETURNING list of the first plan as a reference to
         * calculate attno's for the RETURNING list of this partition.  See
         * the comment above for WCO lists for more details on why this is
         * okay.
         */
        returningList = linitial(node->returningLists);

        /*
         * Convert Vars in it to contain this partition's attribute numbers.
         */
        if (part_attmap == NULL)
            part_attmap =
                build_attrmap_by_name(RelationGetDescr(partrel),
                                      RelationGetDescr(firstResultRel));
        returningList = (List *)
            map_variable_attnos((Node *) returningList,
                                firstVarno, 0,
                                part_attmap,
                                RelationGetForm(partrel)->reltype,
                                &found_whole_row);
        /* We ignore the value of found_whole_row. */

        leaf_part_rri->ri_returningList = returningList;

        /*
         * Initialize the projection itself.
         *
         * Use the slot and the expression context that would have been set up
         * in ExecInitModifyTable() for projection's output.
         */
        Assert(mtstate->ps.ps_ResultTupleSlot != NULL);
        slot = mtstate->ps.ps_ResultTupleSlot;
        Assert(mtstate->ps.ps_ExprContext != NULL);
        econtext = mtstate->ps.ps_ExprContext;
        leaf_part_rri->ri_projectReturning =
            ExecBuildProjectionInfo(returningList, econtext, slot,
                                    &mtstate->ps, RelationGetDescr(partrel));
    }

    /* Set up information needed for routing tuples to the partition. */
    ExecInitRoutingInfo(mtstate, estate, proute, dispatch,
                        leaf_part_rri, partidx);

    /*
     * If there is an ON CONFLICT clause, initialize state for it.
     */
    if (node && node->onConflictAction != ONCONFLICT_NONE)
    {
        TupleDesc   partrelDesc = RelationGetDescr(partrel);
        ExprContext *econtext = mtstate->ps.ps_ExprContext;
        ListCell   *lc;
        List       *arbiterIndexes = NIL;

        /*
         * If there is a list of arbiter indexes, map it to a list of indexes
         * in the partition.  We do that by scanning the partition's index
         * list and searching for ancestry relationships to each index in the
         * ancestor table.
         */
        if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) > 0)
        {
            List       *childIdxs;

            childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);

            foreach(lc, childIdxs)
            {
                Oid         childIdx = lfirst_oid(lc);
                List       *ancestors;
                ListCell   *lc2;

                ancestors = get_partition_ancestors(childIdx);
                foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
                {
                    if (list_member_oid(ancestors, lfirst_oid(lc2)))
                        arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
                }
                list_free(ancestors);
            }
        }

        /*
         * If the resulting lists are of inequal length, something is wrong.
         * (This shouldn't happen, since arbiter index selection should not
         * pick up an invalid index.)
         */
        if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
            list_length(arbiterIndexes))
            elog(ERROR, "invalid arbiter index list");
        leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;

        /*
         * In the DO UPDATE case, we have some more state to initialize.
         */
        if (node->onConflictAction == ONCONFLICT_UPDATE)
        {
            TupleConversionMap *map;

            map = leaf_part_rri->ri_RootToPartitionMap;

            Assert(node->onConflictSet != NIL);
            Assert(rootResultRelInfo->ri_onConflict != NULL);

            leaf_part_rri->ri_onConflict = makeNode(OnConflictSetState);

            /*
             * Need a separate existing slot for each partition, as the
             * partition could be of a different AM, even if the tuple
             * descriptors match.
             */
            leaf_part_rri->ri_onConflict->oc_Existing =
                table_slot_create(leaf_part_rri->ri_RelationDesc,
                                  &mtstate->ps.state->es_tupleTable);

            /*
             * If the partition's tuple descriptor matches exactly the root
             * parent (the common case), we can re-use most of the parent's ON
             * CONFLICT SET state, skipping a bunch of work.  Otherwise, we
             * need to create state specific to this partition.
             */
            if (map == NULL)
            {
                /*
                 * It's safe to reuse these from the partition root, as we
                 * only process one tuple at a time (therefore we won't
                 * overwrite needed data in slots), and the results of
                 * projections are independent of the underlying storage.
                 * Projections and where clauses themselves don't store state
                 * / are independent of the underlying storage.
                 */
                leaf_part_rri->ri_onConflict->oc_ProjSlot =
                    rootResultRelInfo->ri_onConflict->oc_ProjSlot;
                leaf_part_rri->ri_onConflict->oc_ProjInfo =
                    rootResultRelInfo->ri_onConflict->oc_ProjInfo;
                leaf_part_rri->ri_onConflict->oc_WhereClause =
                    rootResultRelInfo->ri_onConflict->oc_WhereClause;
            }
            else
            {
                List       *onconflset;
                TupleDesc   tupDesc;
                bool        found_whole_row;

                /*
                 * Translate expressions in onConflictSet to account for
                 * different attribute numbers.  For that, map partition
                 * varattnos twice: first to catch the EXCLUDED
                 * pseudo-relation (INNER_VAR), and second to handle the main
                 * target relation (firstVarno).
                 */
                onconflset = (List *) copyObject((Node *) node->onConflictSet);
                if (part_attmap == NULL)
                    part_attmap =
                        build_attrmap_by_name(RelationGetDescr(partrel),
                                              RelationGetDescr(firstResultRel));
                onconflset = (List *)
                    map_variable_attnos((Node *) onconflset,
                                        INNER_VAR, 0,
                                        part_attmap,
                                        RelationGetForm(partrel)->reltype,
                                        &found_whole_row);
                /* We ignore the value of found_whole_row. */
                onconflset = (List *)
                    map_variable_attnos((Node *) onconflset,
                                        firstVarno, 0,
                                        part_attmap,
                                        RelationGetForm(partrel)->reltype,
                                        &found_whole_row);
                /* We ignore the value of found_whole_row. */

                /* Finally, adjust this tlist to match the partition. */
                onconflset = adjust_partition_tlist(onconflset, map);

                /* create the tuple slot for the UPDATE SET projection */
                tupDesc = ExecTypeFromTL(onconflset);
                leaf_part_rri->ri_onConflict->oc_ProjSlot =
                    ExecInitExtraTupleSlot(mtstate->ps.state, tupDesc,
                                           &TTSOpsVirtual);

                /* build UPDATE SET projection state */
                leaf_part_rri->ri_onConflict->oc_ProjInfo =
                    ExecBuildProjectionInfo(onconflset, econtext,
                                            leaf_part_rri->ri_onConflict->oc_ProjSlot,
                                            &mtstate->ps, partrelDesc);

                /*
                 * If there is a WHERE clause, initialize state where it will
                 * be evaluated, mapping the attribute numbers appropriately.
                 * As with onConflictSet, we need to map partition varattnos
                 * to the partition's tupdesc.
                 */
                if (node->onConflictWhere)
                {
                    List       *clause;

                    clause = copyObject((List *) node->onConflictWhere);
                    clause = (List *)
                        map_variable_attnos((Node *) clause,
                                            INNER_VAR, 0,
                                            part_attmap,
                                            RelationGetForm(partrel)->reltype,
                                            &found_whole_row);
                    /* We ignore the value of found_whole_row. */
                    clause = (List *)
                        map_variable_attnos((Node *) clause,
                                            firstVarno, 0,
                                            part_attmap,
                                            RelationGetForm(partrel)->reltype,
                                            &found_whole_row);
                    /* We ignore the value of found_whole_row. */
                    leaf_part_rri->ri_onConflict->oc_WhereClause =
                        ExecInitQual((List *) clause, &mtstate->ps);
                }
            }
        }
    }

    /*
     * Also, if transition capture is required, store a map to convert tuples
     * from partition's rowtype to the root partition table's.
     */
    if (mtstate->mt_transition_capture || mtstate->mt_oc_transition_capture)
        leaf_part_rri->ri_ChildToRootMap =
            convert_tuples_by_name(RelationGetDescr(leaf_part_rri->ri_RelationDesc),
                                   RelationGetDescr(rootResultRelInfo->ri_RelationDesc));

    /*
     * Since we've just initialized this ResultRelInfo, it's not in any list
     * attached to the estate as yet.  Add it, so that it can be found later.
     *
     * Note that the entries in this list appear in no predetermined order,
     * because partition result rels are initialized as and when they're
     * needed.
     */
    MemoryContextSwitchTo(estate->es_query_cxt);
    estate->es_tuple_routing_result_relations =
        lappend(estate->es_tuple_routing_result_relations,
                leaf_part_rri);

    MemoryContextSwitchTo(oldcxt);

    return leaf_part_rri;
}

/*
 * ExecInitRoutingInfo
 *      Set up information needed for translating tuples between root
 *      partitioned table format and partition format, and keep track of it
 *      in PartitionTupleRouting.
 */
static void
ExecInitRoutingInfo(ModifyTableState *mtstate,
                    EState *estate,
                    PartitionTupleRouting *proute,
                    PartitionDispatch dispatch,
                    ResultRelInfo *partRelInfo,
                    int partidx)
{
    ResultRelInfo *rootRelInfo = partRelInfo->ri_RootResultRelInfo;
    MemoryContext oldcxt;
    int         rri_index;

    oldcxt = MemoryContextSwitchTo(proute->memcxt);

    /*
     * Set up a tuple conversion map to convert a tuple routed to the
     * partition from the parent's type to the partition's.
     */
    partRelInfo->ri_RootToPartitionMap =
        convert_tuples_by_name(RelationGetDescr(rootRelInfo->ri_RelationDesc),
                               RelationGetDescr(partRelInfo->ri_RelationDesc));

    /*
     * If a partition has a different rowtype than the root parent, initialize
     * a slot dedicated to storing this partition's tuples.  The slot is used
     * for various operations that are applied to tuples after routing, such
     * as checking constraints.
     */
    if (partRelInfo->ri_RootToPartitionMap != NULL)
    {
        Relation    partrel = partRelInfo->ri_RelationDesc;

        /*
         * Initialize the slot itself setting its descriptor to this
         * partition's TupleDesc; TupleDesc reference will be released at the
         * end of the command.
         */
        partRelInfo->ri_PartitionTupleSlot =
            table_slot_create(partrel, &estate->es_tupleTable);
    }
    else
        partRelInfo->ri_PartitionTupleSlot = NULL;

    /*
     * If the partition is a foreign table, let the FDW init itself for
     * routing tuples to the partition.
     */
    if (partRelInfo->ri_FdwRoutine != NULL &&
        partRelInfo->ri_FdwRoutine->BeginForeignInsert != NULL)
        partRelInfo->ri_FdwRoutine->BeginForeignInsert(mtstate, partRelInfo);

    /*
     * Determine if the FDW supports batch insert and determine the batch
     * size (a FDW may support batching, but it may be disabled for the
     * server/table or for this particular query).
     *
     * If the FDW does not support batching, we set the batch size to 1.
     */
    if (mtstate->operation == CMD_INSERT &&
        partRelInfo->ri_FdwRoutine != NULL &&
        partRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize &&
        partRelInfo->ri_FdwRoutine->ExecForeignBatchInsert)
        partRelInfo->ri_BatchSize =
            partRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize(partRelInfo);
    else
        partRelInfo->ri_BatchSize = 1;

    Assert(partRelInfo->ri_BatchSize >= 1);

    partRelInfo->ri_CopyMultiInsertBuffer = NULL;

    /*
     * Keep track of it in the PartitionTupleRouting->partitions array.
     */
    Assert(dispatch->indexes[partidx] == -1);

    rri_index = proute->num_partitions++;

    /* Allocate or enlarge the array, as needed */
    if (proute->num_partitions >= proute->max_partitions)
    {
        if (proute->max_partitions == 0)
        {
            proute->max_partitions = 8;
            proute->partitions = (ResultRelInfo **)
                palloc(sizeof(ResultRelInfo *) * proute->max_partitions);
        }
        else
        {
            proute->max_partitions *= 2;
            proute->partitions = (ResultRelInfo **)
                repalloc(proute->partitions, sizeof(ResultRelInfo *) *
                         proute->max_partitions);
        }
    }

    proute->partitions[rri_index] = partRelInfo;
    dispatch->indexes[partidx] = rri_index;

    MemoryContextSwitchTo(oldcxt);
}

/*
 * ExecInitPartitionDispatchInfo
 *      Lock the partitioned table (if not locked already) and initialize
 *      PartitionDispatch for a partitioned table and store it in the next
 *      available slot in the proute->partition_dispatch_info array.  Also,
 *      record the index into this array in the parent_pd->indexes[] array in
 *      the partidx element so that we can properly retrieve the newly created
 *      PartitionDispatch later.
 */
static PartitionDispatch
ExecInitPartitionDispatchInfo(EState *estate,
                              PartitionTupleRouting *proute, Oid partoid,
                              PartitionDispatch parent_pd, int partidx,
                              ResultRelInfo *rootResultRelInfo)
{
    Relation    rel;
    PartitionDesc partdesc;
    PartitionDispatch pd;
    int         dispatchidx;
    MemoryContext oldcxt;

    if (estate->es_partition_directory == NULL)
        estate->es_partition_directory =
            CreatePartitionDirectory(estate->es_query_cxt);

    oldcxt = MemoryContextSwitchTo(proute->memcxt);

    /*
     * Only sub-partitioned tables need to be locked here.  The root
     * partitioned table will already have been locked as it's referenced in
     * the query's rtable.
     */
    if (partoid != RelationGetRelid(proute->partition_root))
        rel = table_open(partoid, RowExclusiveLock);
    else
        rel = proute->partition_root;
    partdesc = PartitionDirectoryLookup(estate->es_partition_directory, rel);

    pd = (PartitionDispatch) palloc(offsetof(PartitionDispatchData, indexes) +
                                    partdesc->nparts * sizeof(int));
    pd->reldesc = rel;
    pd->key = RelationGetPartitionKey(rel);
    pd->keystate = NIL;
    pd->partdesc = partdesc;
    if (parent_pd != NULL)
    {
        TupleDesc   tupdesc = RelationGetDescr(rel);

        /*
         * For sub-partitioned tables where the column order differs from its
         * direct parent partitioned table, we must store a tuple table slot
         * initialized with its tuple descriptor and a tuple conversion map to
         * convert a tuple from its parent's rowtype to its own.  This is to
         * make sure that we are looking at the correct row using the correct
         * tuple descriptor when computing its partition key for tuple
         * routing.
         */
        pd->tupmap = build_attrmap_by_name_if_req(RelationGetDescr(parent_pd->reldesc),
                                                  tupdesc);
        pd->tupslot = pd->tupmap ?
            MakeSingleTupleTableSlot(tupdesc, &TTSOpsVirtual) : NULL;
    }
    else
    {
        /* Not required for the root partitioned table */
        pd->tupmap = NULL;
        pd->tupslot = NULL;
    }

    /*
     * Initialize with -1 to signify that the corresponding partition's
     * ResultRelInfo or PartitionDispatch has not been created yet.
     */
    memset(pd->indexes, -1, sizeof(int) * partdesc->nparts);

    /* Track in PartitionTupleRouting for later use */
    dispatchidx = proute->num_dispatch++;

    /* Allocate or enlarge the array, as needed */
    if (proute->num_dispatch >= proute->max_dispatch)
    {
        if (proute->max_dispatch == 0)
        {
            proute->max_dispatch = 4;
            proute->partition_dispatch_info = (PartitionDispatch *)
                palloc(sizeof(PartitionDispatch) * proute->max_dispatch);
            proute->nonleaf_partitions = (ResultRelInfo **)
                palloc(sizeof(ResultRelInfo *) * proute->max_dispatch);
        }
        else
        {
            proute->max_dispatch *= 2;
            proute->partition_dispatch_info = (PartitionDispatch *)
                repalloc(proute->partition_dispatch_info,
                         sizeof(PartitionDispatch) * proute->max_dispatch);
            proute->nonleaf_partitions = (ResultRelInfo **)
                repalloc(proute->nonleaf_partitions,
                         sizeof(ResultRelInfo *) * proute->max_dispatch);
        }
    }
    proute->partition_dispatch_info[dispatchidx] = pd;

    /*
     * If setting up a PartitionDispatch for a sub-partitioned table, we may
     * also need a minimally valid ResultRelInfo for checking the partition
     * constraint later; set that up now.
     */
    if (parent_pd)
    {
        ResultRelInfo *rri = makeNode(ResultRelInfo);

        InitResultRelInfo(rri, rel, 0, rootResultRelInfo, 0);
        proute->nonleaf_partitions[dispatchidx] = rri;
    }
    else
        proute->nonleaf_partitions[dispatchidx] = NULL;

    /*
     * Finally, if setting up a PartitionDispatch for a sub-partitioned table,
     * install a downlink in the parent to allow quick descent.
     */
    if (parent_pd)
    {
        Assert(parent_pd->indexes[partidx] == -1);
        parent_pd->indexes[partidx] = dispatchidx;
    }

    MemoryContextSwitchTo(oldcxt);

    return pd;
}

/*
 * ExecCleanupTupleRouting -- Clean up objects allocated for partition tuple
 * routing.
 *
 * Close all the partitioned tables, leaf partitions, and their indices.
 */
void
ExecCleanupTupleRouting(ModifyTableState *mtstate,
                        PartitionTupleRouting *proute)
{
    HTAB       *htab = proute->subplan_resultrel_htab;
    int         i;

    /*
     * Remember, proute->partition_dispatch_info[0] corresponds to the root
     * partitioned table, which we must not try to close, because it is the
     * main target table of the query that will be closed by callers such as
     * ExecEndPlan() or DoCopy(). Also, tupslot is NULL for the root
     * partitioned table.
     */
    for (i = 1; i < proute->num_dispatch; i++)
    {
        PartitionDispatch pd = proute->partition_dispatch_info[i];

        table_close(pd->reldesc, NoLock);

        if (pd->tupslot)
            ExecDropSingleTupleTableSlot(pd->tupslot);
    }

    for (i = 0; i < proute->num_partitions; i++)
    {
        ResultRelInfo *resultRelInfo = proute->partitions[i];

        /* Allow any FDWs to shut down */
        if (resultRelInfo->ri_FdwRoutine != NULL &&
            resultRelInfo->ri_FdwRoutine->EndForeignInsert != NULL)
            resultRelInfo->ri_FdwRoutine->EndForeignInsert(mtstate->ps.state,
                                                           resultRelInfo);

        /*
         * Check if this result rel is one belonging to the node's subplans,
         * if so, let ExecEndPlan() clean it up.
         */
        if (htab)
        {
            Oid         partoid;
            bool        found;

            partoid = RelationGetRelid(resultRelInfo->ri_RelationDesc);

            (void) hash_search(htab, &partoid, HASH_FIND, &found);
            if (found)
                continue;
        }

        ExecCloseIndices(resultRelInfo);
        table_close(resultRelInfo->ri_RelationDesc, NoLock);
    }
}

/* ----------------
 *      FormPartitionKeyDatum
 *          Construct values[] and isnull[] arrays for the partition key
 *          of a tuple.
 *
 *  pd              Partition dispatch object of the partitioned table
 *  slot            Heap tuple from which to extract partition key
 *  estate          executor state for evaluating any partition key
 *                  expressions (must be non-NULL)
 *  values          Array of partition key Datums (output area)
 *  isnull          Array of is-null indicators (output area)
 *
 * the ecxt_scantuple slot of estate's per-tuple expr context must point to
 * the heap tuple passed in.
 * ----------------
 */
static void
FormPartitionKeyDatum(PartitionDispatch pd,
                      TupleTableSlot *slot,
                      EState *estate,
                      Datum *values,
                      bool *isnull)
{
    ListCell   *partexpr_item;
    int         i;

    if (pd->key->partexprs != NIL && pd->keystate == NIL)
    {
        /* Check caller has set up context correctly */
        Assert(estate != NULL &&
               GetPerTupleExprContext(estate)->ecxt_scantuple == slot);

        /* First time through, set up expression evaluation state */
        pd->keystate = ExecPrepareExprList(pd->key->partexprs, estate);
    }

    partexpr_item = list_head(pd->keystate);
    for (i = 0; i < pd->key->partnatts; i++)
    {
        AttrNumber  keycol = pd->key->partattrs[i];
        Datum       datum;
        bool        isNull;

        if (keycol != 0)
        {
            /* Plain column; get the value directly from the heap tuple */
            datum = slot_getattr(slot, keycol, &isNull);
        }
        else
        {
            /* Expression; need to evaluate it */
            if (partexpr_item == NULL)
                elog(ERROR, "wrong number of partition key expressions");
            datum = ExecEvalExprSwitchContext((ExprState *) lfirst(partexpr_item),
                                              GetPerTupleExprContext(estate),
                                              &isNull);
            partexpr_item = lnext(pd->keystate, partexpr_item);
        }
        values[i] = datum;
        isnull[i] = isNull;
    }

    if (partexpr_item != NULL)
        elog(ERROR, "wrong number of partition key expressions");
}

/*
 * get_partition_for_tuple
 *      Finds partition of relation which accepts the partition key specified
 *      in values and isnull
 *
 * Return value is index of the partition (>= 0 and < partdesc->nparts) if one
 * found or -1 if none found.
 */
static int
get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
{
    int         bound_offset;
    int         part_index = -1;
    PartitionKey key = pd->key;
    PartitionDesc partdesc = pd->partdesc;
    PartitionBoundInfo boundinfo = partdesc->boundinfo;

    /* Route as appropriate based on partitioning strategy. */
    switch (key->strategy)
    {
        case PARTITION_STRATEGY_HASH:
            {
                uint64      rowHash;

                rowHash = compute_partition_hash_value(key->partnatts,
                                                       key->partsupfunc,
                                                       key->partcollation,
                                                       values, isnull);

                part_index = boundinfo->indexes[rowHash % boundinfo->nindexes];
            }
            break;

        case PARTITION_STRATEGY_LIST:
            if (isnull[0])
            {
                if (partition_bound_accepts_nulls(boundinfo))
                    part_index = boundinfo->null_index;
            }
            else
            {
                bool        equal = false;

                bound_offset = partition_list_bsearch(key->partsupfunc,
                                                      key->partcollation,
                                                      boundinfo,
                                                      values[0], &equal);
                if (bound_offset >= 0 && equal)
                    part_index = boundinfo->indexes[bound_offset];
            }
            break;

        case PARTITION_STRATEGY_RANGE:
            {
                bool        equal = false,
                            range_partkey_has_null = false;
                int         i;

                /*
                 * No range includes NULL, so this will be accepted by the
                 * default partition if there is one, and otherwise rejected.
                 */
                for (i = 0; i < key->partnatts; i++)
                {
                    if (isnull[i])
                    {
                        range_partkey_has_null = true;
                        break;
                    }
                }

                if (!range_partkey_has_null)
                {
                    bound_offset = partition_range_datum_bsearch(key->partsupfunc,
                                                                 key->partcollation,
                                                                 boundinfo,
                                                                 key->partnatts,
                                                                 values,
                                                                 &equal);

                    /*
                     * The bound at bound_offset is less than or equal to the
                     * tuple value, so the bound at offset+1 is the upper
                     * bound of the partition we're looking for, if there
                     * actually exists one.
                     */
                    part_index = boundinfo->indexes[bound_offset + 1];
                }
            }
            break;

        default:
            elog(ERROR, "unexpected partition strategy: %d",
                 (int) key->strategy);
    }

    /*
     * part_index < 0 means we failed to find a partition of this parent. Use
     * the default partition, if there is one.
     */
    if (part_index < 0)
        part_index = boundinfo->default_index;

    return part_index;
}

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

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

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

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

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

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

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

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

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

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

    appendStringInfoChar(&buf, ')');

    return buf.data;
}

/*
 * adjust_partition_tlist
 *      Adjust the targetlist entries for a given partition to account for
 *      attribute differences between parent and the partition
 *
 * The expressions have already been fixed, but here we fix the list to make
 * target resnos match the partition's attribute numbers.  This results in a
 * copy of the original target list in which the entries appear in resno
 * order, including both the existing entries (that may have their resno
 * changed in-place) and the newly added entries for columns that don't exist
 * in the parent.
 *
 * Scribbles on the input tlist, so callers must make sure to make a copy
 * before passing it to us.
 */
static List *
adjust_partition_tlist(List *tlist, TupleConversionMap *map)
{
    List       *new_tlist = NIL;
    TupleDesc   tupdesc = map->outdesc;
    AttrMap    *attrMap = map->attrMap;
    AttrNumber  attrno;

    Assert(tupdesc->natts == attrMap->maplen);
    for (attrno = 1; attrno <= tupdesc->natts; attrno++)
    {
        Form_pg_attribute att_tup = TupleDescAttr(tupdesc, attrno - 1);
        TargetEntry *tle;

        if (attrMap->attnums[attrno - 1] != InvalidAttrNumber)
        {
            Assert(!att_tup->attisdropped);

            /*
             * Use the corresponding entry from the parent's tlist, adjusting
             * the resno the match the partition's attno.
             */
            tle = (TargetEntry *) list_nth(tlist, attrMap->attnums[attrno - 1] - 1);
            tle->resno = attrno;
        }
        else
        {
            Const      *expr;

            /*
             * For a dropped attribute in the partition, generate a dummy
             * entry with resno matching the partition's attno.
             */
            Assert(att_tup->attisdropped);
            expr = makeConst(INT4OID,
                             -1,
                             InvalidOid,
                             sizeof(int32),
                             (Datum) 0,
                             true,  /* isnull */
                             true /* byval */ );
            tle = makeTargetEntry((Expr *) expr,
                                  attrno,
                                  pstrdup(NameStr(att_tup->attname)),
                                  false);
        }

        new_tlist = lappend(new_tlist, tle);
    }

    return new_tlist;
}

/*-------------------------------------------------------------------------
 * Run-Time Partition Pruning Support.
 *
 * The following series of functions exist to support the removal of unneeded
 * subplans for queries against partitioned tables.  The supporting functions
 * here are designed to work with any plan type which supports an arbitrary
 * number of subplans, e.g. Append, MergeAppend.
 *
 * When pruning involves comparison of a partition key to a constant, it's
 * done by the planner.  However, if we have a comparison to a non-constant
 * but not volatile expression, that presents an opportunity for run-time
 * pruning by the executor, allowing irrelevant partitions to be skipped
 * dynamically.
 *
 * We must distinguish expressions containing PARAM_EXEC Params from
 * expressions that don't contain those.  Even though a PARAM_EXEC Param is
 * considered to be a stable expression, it can change value from one plan
 * node scan to the next during query execution.  Stable comparison
 * expressions that don't involve such Params allow partition pruning to be
 * done once during executor startup.  Expressions that do involve such Params
 * require us to prune separately for each scan of the parent plan node.
 *
 * Note that pruning away unneeded subplans during executor startup has the
 * added benefit of not having to initialize the unneeded subplans at all.
 *
 *
 * Functions:
 *
 * ExecCreatePartitionPruneState:
 *      Creates the PartitionPruneState required by each of the two pruning
 *      functions.  Details stored include how to map the partition index
 *      returned by the partition pruning code into subplan indexes.
 *
 * ExecFindInitialMatchingSubPlans:
 *      Returns indexes of matching subplans.  Partition pruning is attempted
 *      without any evaluation of expressions containing PARAM_EXEC Params.
 *      This function must be called during executor startup for the parent
 *      plan before the subplans themselves are initialized.  Subplans which
 *      are found not to match by this function must be removed from the
 *      plan's list of subplans during execution, as this function performs a
 *      remap of the partition index to subplan index map and the newly
 *      created map provides indexes only for subplans which remain after
 *      calling this function.
 *
 * ExecFindMatchingSubPlans:
 *      Returns indexes of matching subplans after evaluating all available
 *      expressions.  This function can only be called during execution and
 *      must be called again each time the value of a Param listed in
 *      PartitionPruneState's 'execparamids' changes.
 *-------------------------------------------------------------------------
 */

/*
 * ExecCreatePartitionPruneState
 *      Build the data structure required for calling
 *      ExecFindInitialMatchingSubPlans and ExecFindMatchingSubPlans.
 *
 * 'planstate' is the parent plan node's execution state.
 *
 * 'partitionpruneinfo' is a PartitionPruneInfo as generated by
 * make_partition_pruneinfo.  Here we build a PartitionPruneState containing a
 * PartitionPruningData for each partitioning hierarchy (i.e., each sublist of
 * partitionpruneinfo->prune_infos), each of which contains a
 * PartitionedRelPruningData for each PartitionedRelPruneInfo appearing in
 * that sublist.  This two-level system is needed to keep from confusing the
 * different hierarchies when a UNION ALL contains multiple partitioned tables
 * as children.  The data stored in each PartitionedRelPruningData can be
 * re-used each time we re-evaluate which partitions match the pruning steps
 * provided in each PartitionedRelPruneInfo.
 */
PartitionPruneState *
ExecCreatePartitionPruneState(PlanState *planstate,
                              PartitionPruneInfo *partitionpruneinfo)
{
    EState     *estate = planstate->state;
    PartitionPruneState *prunestate;
    int         n_part_hierarchies;
    ListCell   *lc;
    int         i;

    if (estate->es_partition_directory == NULL)
        estate->es_partition_directory =
            CreatePartitionDirectory(estate->es_query_cxt);

    n_part_hierarchies = list_length(partitionpruneinfo->prune_infos);
    Assert(n_part_hierarchies > 0);

    /*
     * Allocate the data structure
     */
    prunestate = (PartitionPruneState *)
        palloc(offsetof(PartitionPruneState, partprunedata) +
               sizeof(PartitionPruningData *) * n_part_hierarchies);

    prunestate->execparamids = NULL;
    /* other_subplans can change at runtime, so we need our own copy */
    prunestate->other_subplans = bms_copy(partitionpruneinfo->other_subplans);
    prunestate->do_initial_prune = false;   /* may be set below */
    prunestate->do_exec_prune = false;  /* may be set below */
    prunestate->num_partprunedata = n_part_hierarchies;

    /*
     * Create a short-term memory context which we'll use when making calls to
     * the partition pruning functions.  This avoids possible memory leaks,
     * since the pruning functions call comparison functions that aren't under
     * our control.
     */
    prunestate->prune_context =
        AllocSetContextCreate(CurrentMemoryContext,
                              "Partition Prune",
                              ALLOCSET_DEFAULT_SIZES);

    i = 0;
    foreach(lc, partitionpruneinfo->prune_infos)
    {
        List       *partrelpruneinfos = lfirst_node(List, lc);
        int         npartrelpruneinfos = list_length(partrelpruneinfos);
        PartitionPruningData *prunedata;
        ListCell   *lc2;
        int         j;

        prunedata = (PartitionPruningData *)
            palloc(offsetof(PartitionPruningData, partrelprunedata) +
                   npartrelpruneinfos * sizeof(PartitionedRelPruningData));
        prunestate->partprunedata[i] = prunedata;
        prunedata->num_partrelprunedata = npartrelpruneinfos;

        j = 0;
        foreach(lc2, partrelpruneinfos)
        {
            PartitionedRelPruneInfo *pinfo = lfirst_node(PartitionedRelPruneInfo, lc2);
            PartitionedRelPruningData *pprune = &prunedata->partrelprunedata[j];
            Relation    partrel;
            PartitionDesc partdesc;
            PartitionKey partkey;

            /*
             * We can rely on the copies of the partitioned table's partition
             * key and partition descriptor appearing in its relcache entry,
             * because that entry will be held open and locked for the
             * duration of this executor run.
             */
            partrel = ExecGetRangeTableRelation(estate, pinfo->rtindex);
            partkey = RelationGetPartitionKey(partrel);
            partdesc = PartitionDirectoryLookup(estate->es_partition_directory,
                                                partrel);

            /*
             * Initialize the subplan_map and subpart_map.  Since detaching a
             * partition requires AccessExclusiveLock, no partitions can have
             * disappeared, nor can the bounds for any partition have changed.
             * However, new partitions may have been added.
             */
            Assert(partdesc->nparts >= pinfo->nparts);
            pprune->nparts = partdesc->nparts;
            pprune->subplan_map = palloc(sizeof(int) * partdesc->nparts);
            if (partdesc->nparts == pinfo->nparts)
            {
                /*
                 * There are no new partitions, so this is simple.  We can
                 * simply point to the subpart_map from the plan, but we must
                 * copy the subplan_map since we may change it later.
                 */
                pprune->subpart_map = pinfo->subpart_map;
                memcpy(pprune->subplan_map, pinfo->subplan_map,
                       sizeof(int) * pinfo->nparts);

                /*
                 * Double-check that the list of unpruned relations has not
                 * changed.  (Pruned partitions are not in relid_map[].)
                 */
#ifdef USE_ASSERT_CHECKING
                for (int k = 0; k < pinfo->nparts; k++)
                {
                    Assert(partdesc->oids[k] == pinfo->relid_map[k] ||
                           pinfo->subplan_map[k] == -1);
                }
#endif
            }
            else
            {
                int         pd_idx = 0;
                int         pp_idx;

                /*
                 * Some new partitions have appeared since plan time, and
                 * those are reflected in our PartitionDesc but were not
                 * present in the one used to construct subplan_map and
                 * subpart_map.  So we must construct new and longer arrays
                 * where the partitions that were originally present map to
                 * the same sub-structures, and any added partitions map to
                 * -1, as if the new partitions had been pruned.
                 *
                 * Note: pinfo->relid_map[] may contain InvalidOid entries for
                 * partitions pruned by the planner.  We cannot tell exactly
                 * which of the partdesc entries these correspond to, but we
                 * don't have to; just skip over them.  The non-pruned
                 * relid_map entries, however, had better be a subset of the
                 * partdesc entries and in the same order.
                 */
                pprune->subpart_map = palloc(sizeof(int) * partdesc->nparts);
                for (pp_idx = 0; pp_idx < partdesc->nparts; pp_idx++)
                {
                    /* Skip any InvalidOid relid_map entries */
                    while (pd_idx < pinfo->nparts &&
                           !OidIsValid(pinfo->relid_map[pd_idx]))
                        pd_idx++;

                    if (pd_idx < pinfo->nparts &&
                        pinfo->relid_map[pd_idx] == partdesc->oids[pp_idx])
                    {
                        /* match... */
                        pprune->subplan_map[pp_idx] =
                            pinfo->subplan_map[pd_idx];
                        pprune->subpart_map[pp_idx] =
                            pinfo->subpart_map[pd_idx];
                        pd_idx++;
                    }
                    else
                    {
                        /* this partdesc entry is not in the plan */
                        pprune->subplan_map[pp_idx] = -1;
                        pprune->subpart_map[pp_idx] = -1;
                    }
                }

                /*
                 * It might seem that we need to skip any trailing InvalidOid
                 * entries in pinfo->relid_map before checking that we scanned
                 * all of the relid_map.  But we will have skipped them above,
                 * because they must correspond to some partdesc->oids
                 * entries; we just couldn't tell which.
                 */
                if (pd_idx != pinfo->nparts)
                    elog(ERROR, "could not match partition child tables to plan elements");
            }

            /* present_parts is also subject to later modification */
            pprune->present_parts = bms_copy(pinfo->present_parts);

            /*
             * Initialize pruning contexts as needed.
             */
            pprune->initial_pruning_steps = pinfo->initial_pruning_steps;
            if (pinfo->initial_pruning_steps)
            {
                ExecInitPruningContext(&pprune->initial_context,
                                       pinfo->initial_pruning_steps,
                                       partdesc, partkey, planstate);
                /* Record whether initial pruning is needed at any level */
                prunestate->do_initial_prune = true;
            }
            pprune->exec_pruning_steps = pinfo->exec_pruning_steps;
            if (pinfo->exec_pruning_steps)
            {
                ExecInitPruningContext(&pprune->exec_context,
                                       pinfo->exec_pruning_steps,
                                       partdesc, partkey, planstate);
                /* Record whether exec pruning is needed at any level */
                prunestate->do_exec_prune = true;
            }

            /*
             * Accumulate the IDs of all PARAM_EXEC Params affecting the
             * partitioning decisions at this plan node.
             */
            prunestate->execparamids = bms_add_members(prunestate->execparamids,
                                                       pinfo->execparamids);

            j++;
        }
        i++;
    }

    return prunestate;
}

/*
 * Initialize a PartitionPruneContext for the given list of pruning steps.
 */
static void
ExecInitPruningContext(PartitionPruneContext *context,
                       List *pruning_steps,
                       PartitionDesc partdesc,
                       PartitionKey partkey,
                       PlanState *planstate)
{
    int         n_steps;
    int         partnatts;
    ListCell   *lc;

    n_steps = list_length(pruning_steps);

    context->strategy = partkey->strategy;
    context->partnatts = partnatts = partkey->partnatts;
    context->nparts = partdesc->nparts;
    context->boundinfo = partdesc->boundinfo;
    context->partcollation = partkey->partcollation;
    context->partsupfunc = partkey->partsupfunc;

    /* We'll look up type-specific support functions as needed */
    context->stepcmpfuncs = (FmgrInfo *)
        palloc0(sizeof(FmgrInfo) * n_steps * partnatts);

    context->ppccontext = CurrentMemoryContext;
    context->planstate = planstate;

    /* Initialize expression state for each expression we need */
    context->exprstates = (ExprState **)
        palloc0(sizeof(ExprState *) * n_steps * partnatts);
    foreach(lc, pruning_steps)
    {
        PartitionPruneStepOp *step = (PartitionPruneStepOp *) lfirst(lc);
        ListCell   *lc2;
        int         keyno;

        /* not needed for other step kinds */
        if (!IsA(step, PartitionPruneStepOp))
            continue;

        Assert(list_length(step->exprs) <= partnatts);

        keyno = 0;
        foreach(lc2, step->exprs)
        {
            Expr       *expr = (Expr *) lfirst(lc2);

            /* not needed for Consts */
            if (!IsA(expr, Const))
            {
                int         stateidx = PruneCxtStateIdx(partnatts,
                                                        step->step.step_id,
                                                        keyno);

                context->exprstates[stateidx] =
                    ExecInitExpr(expr, context->planstate);
            }
            keyno++;
        }
    }
}

/*
 * ExecFindInitialMatchingSubPlans
 *      Identify the set of subplans that cannot be eliminated by initial
 *      pruning, disregarding any pruning constraints involving PARAM_EXEC
 *      Params.
 *
 * If additional pruning passes will be required (because of PARAM_EXEC
 * Params), we must also update the translation data that allows conversion
 * of partition indexes into subplan indexes to account for the unneeded
 * subplans having been removed.
 *
 * Must only be called once per 'prunestate', and only if initial pruning
 * is required.
 *
 * 'nsubplans' must be passed as the total number of unpruned subplans.
 */
Bitmapset *
ExecFindInitialMatchingSubPlans(PartitionPruneState *prunestate, int nsubplans)
{
    Bitmapset  *result = NULL;
    MemoryContext oldcontext;
    int         i;

    /* Caller error if we get here without do_initial_prune */
    Assert(prunestate->do_initial_prune);

    /*
     * Switch to a temp context to avoid leaking memory in the executor's
     * query-lifespan memory context.
     */
    oldcontext = MemoryContextSwitchTo(prunestate->prune_context);

    /*
     * For each hierarchy, do the pruning tests, and add nondeletable
     * subplans' indexes to "result".
     */
    for (i = 0; i < prunestate->num_partprunedata; i++)
    {
        PartitionPruningData *prunedata;
        PartitionedRelPruningData *pprune;

        prunedata = prunestate->partprunedata[i];
        pprune = &prunedata->partrelprunedata[0];

        /* Perform pruning without using PARAM_EXEC Params */
        find_matching_subplans_recurse(prunedata, pprune, true, &result);

        /* Expression eval may have used space in node's ps_ExprContext too */
        if (pprune->initial_pruning_steps)
            ResetExprContext(pprune->initial_context.planstate->ps_ExprContext);
    }

    /* Add in any subplans that partition pruning didn't account for */
    result = bms_add_members(result, prunestate->other_subplans);

    MemoryContextSwitchTo(oldcontext);

    /* Copy result out of the temp context before we reset it */
    result = bms_copy(result);

    MemoryContextReset(prunestate->prune_context);

    /*
     * If exec-time pruning is required and we pruned subplans above, then we
     * must re-sequence the subplan indexes so that ExecFindMatchingSubPlans
     * properly returns the indexes from the subplans which will remain after
     * execution of this function.
     *
     * We can safely skip this when !do_exec_prune, even though that leaves
     * invalid data in prunestate, because that data won't be consulted again
     * (cf initial Assert in ExecFindMatchingSubPlans).
     */
    if (prunestate->do_exec_prune && bms_num_members(result) < nsubplans)
    {
        int        *new_subplan_indexes;
        Bitmapset  *new_other_subplans;
        int         i;
        int         newidx;

        /*
         * First we must build a temporary array which maps old subplan
         * indexes to new ones.  For convenience of initialization, we use
         * 1-based indexes in this array and leave pruned items as 0.
         */
        new_subplan_indexes = (int *) palloc0(sizeof(int) * nsubplans);
        newidx = 1;
        i = -1;
        while ((i = bms_next_member(result, i)) >= 0)
        {
            Assert(i < nsubplans);
            new_subplan_indexes[i] = newidx++;
        }

        /*
         * Now we can update each PartitionedRelPruneInfo's subplan_map with
         * new subplan indexes.  We must also recompute its present_parts
         * bitmap.
         */
        for (i = 0; i < prunestate->num_partprunedata; i++)
        {
            PartitionPruningData *prunedata = prunestate->partprunedata[i];
            int         j;

            /*
             * Within each hierarchy, we perform this loop in back-to-front
             * order so that we determine present_parts for the lowest-level
             * partitioned tables first.  This way we can tell whether a
             * sub-partitioned table's partitions were entirely pruned so we
             * can exclude it from the current level's present_parts.
             */
            for (j = prunedata->num_partrelprunedata - 1; j >= 0; j--)
            {
                PartitionedRelPruningData *pprune = &prunedata->partrelprunedata[j];
                int         nparts = pprune->nparts;
                int         k;

                /* We just rebuild present_parts from scratch */
                bms_free(pprune->present_parts);
                pprune->present_parts = NULL;

                for (k = 0; k < nparts; k++)
                {
                    int         oldidx = pprune->subplan_map[k];
                    int         subidx;

                    /*
                     * If this partition existed as a subplan then change the
                     * old subplan index to the new subplan index.  The new
                     * index may become -1 if the partition was pruned above,
                     * or it may just come earlier in the subplan list due to
                     * some subplans being removed earlier in the list.  If
                     * it's a subpartition, add it to present_parts unless
                     * it's entirely pruned.
                     */
                    if (oldidx >= 0)
                    {
                        Assert(oldidx < nsubplans);
                        pprune->subplan_map[k] = new_subplan_indexes[oldidx] - 1;

                        if (new_subplan_indexes[oldidx] > 0)
                            pprune->present_parts =
                                bms_add_member(pprune->present_parts, k);
                    }
                    else if ((subidx = pprune->subpart_map[k]) >= 0)
                    {
                        PartitionedRelPruningData *subprune;

                        subprune = &prunedata->partrelprunedata[subidx];

                        if (!bms_is_empty(subprune->present_parts))
                            pprune->present_parts =
                                bms_add_member(pprune->present_parts, k);
                    }
                }
            }
        }

        /*
         * We must also recompute the other_subplans set, since indexes in it
         * may change.
         */
        new_other_subplans = NULL;
        i = -1;
        while ((i = bms_next_member(prunestate->other_subplans, i)) >= 0)
            new_other_subplans = bms_add_member(new_other_subplans,
                                                new_subplan_indexes[i] - 1);

        bms_free(prunestate->other_subplans);
        prunestate->other_subplans = new_other_subplans;

        pfree(new_subplan_indexes);
    }

    return result;
}

/*
 * ExecFindMatchingSubPlans
 *      Determine which subplans match the pruning steps detailed in
 *      'prunestate' for the current comparison expression values.
 *
 * Here we assume we may evaluate PARAM_EXEC Params.
 */
Bitmapset *
ExecFindMatchingSubPlans(PartitionPruneState *prunestate)
{
    Bitmapset  *result = NULL;
    MemoryContext oldcontext;
    int         i;

    /*
     * If !do_exec_prune, we've got problems because
     * ExecFindInitialMatchingSubPlans will not have bothered to update
     * prunestate for whatever pruning it did.
     */
    Assert(prunestate->do_exec_prune);

    /*
     * Switch to a temp context to avoid leaking memory in the executor's
     * query-lifespan memory context.
     */
    oldcontext = MemoryContextSwitchTo(prunestate->prune_context);

    /*
     * For each hierarchy, do the pruning tests, and add nondeletable
     * subplans' indexes to "result".
     */
    for (i = 0; i < prunestate->num_partprunedata; i++)
    {
        PartitionPruningData *prunedata;
        PartitionedRelPruningData *pprune;

        prunedata = prunestate->partprunedata[i];
        pprune = &prunedata->partrelprunedata[0];

        find_matching_subplans_recurse(prunedata, pprune, false, &result);

        /* Expression eval may have used space in node's ps_ExprContext too */
        if (pprune->exec_pruning_steps)
            ResetExprContext(pprune->exec_context.planstate->ps_ExprContext);
    }

    /* Add in any subplans that partition pruning didn't account for */
    result = bms_add_members(result, prunestate->other_subplans);

    MemoryContextSwitchTo(oldcontext);

    /* Copy result out of the temp context before we reset it */
    result = bms_copy(result);

    MemoryContextReset(prunestate->prune_context);

    return result;
}

/*
 * find_matching_subplans_recurse
 *      Recursive worker function for ExecFindMatchingSubPlans and
 *      ExecFindInitialMatchingSubPlans
 *
 * Adds valid (non-prunable) subplan IDs to *validsubplans
 */
static void
find_matching_subplans_recurse(PartitionPruningData *prunedata,
                               PartitionedRelPruningData *pprune,
                               bool initial_prune,
                               Bitmapset **validsubplans)
{
    Bitmapset  *partset;
    int         i;

    /* Guard against stack overflow due to overly deep partition hierarchy. */
    check_stack_depth();

    /* Only prune if pruning would be useful at this level. */
    if (initial_prune && pprune->initial_pruning_steps)
    {
        partset = get_matching_partitions(&pprune->initial_context,
                                          pprune->initial_pruning_steps);
    }
    else if (!initial_prune && pprune->exec_pruning_steps)
    {
        partset = get_matching_partitions(&pprune->exec_context,
                                          pprune->exec_pruning_steps);
    }
    else
    {
        /*
         * If no pruning is to be done, just include all partitions at this
         * level.
         */
        partset = pprune->present_parts;
    }

    /* Translate partset into subplan indexes */
    i = -1;
    while ((i = bms_next_member(partset, i)) >= 0)
    {
        if (pprune->subplan_map[i] >= 0)
            *validsubplans = bms_add_member(*validsubplans,
                                            pprune->subplan_map[i]);
        else
        {
            int         partidx = pprune->subpart_map[i];

            if (partidx >= 0)
                find_matching_subplans_recurse(prunedata,
                                               &prunedata->partrelprunedata[partidx],
                                               initial_prune, validsubplans);
            else
            {
                /*
                 * We get here if the planner already pruned all the sub-
                 * partitions for this partition.  Silently ignore this
                 * partition in this case.  The end result is the same: we
                 * would have pruned all partitions just the same, but we
                 * don't have any pruning steps to execute to verify this.
                 */
            }
        }
    }
}