Add support for user-defined I/O conversion casts.

[PostgreSQL.git] / src / backend / executor / execUtils.c

/*-------------------------------------------------------------------------
 *
 * execUtils.c
 *        miscellaneous executor utility routines
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        $PostgreSQL$
 *
 *-------------------------------------------------------------------------
 */
/*
 * INTERFACE ROUTINES
 *              CreateExecutorState             Create/delete executor working state
 *              FreeExecutorState
 *              CreateExprContext
 *              CreateStandaloneExprContext
 *              FreeExprContext
 *              ReScanExprContext
 *
 *              ExecAssignExprContext   Common code for plan node init routines.
 *              ExecAssignResultType
 *              etc
 *
 *              ExecOpenScanRelation    Common code for scan node init routines.
 *              ExecCloseScanRelation
 *
 *              ExecOpenIndices                 \
 *              ExecCloseIndices                 | referenced by InitPlan, EndPlan,
 *              ExecInsertIndexTuples   /  ExecInsert, ExecUpdate
 *
 *              RegisterExprContextCallback    Register function shutdown callback
 *              UnregisterExprContextCallback  Deregister function shutdown callback
 *
 *       NOTES
 *              This file has traditionally been the place to stick misc.
 *              executor support stuff that doesn't really go anyplace else.
 */

#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "catalog/index.h"
#include "executor/execdebug.h"
#include "parser/parsetree.h"
#include "utils/memutils.h"
#include "utils/relcache.h"
#include "utils/tqual.h"


/* ----------------------------------------------------------------
 *              global counters for number of tuples processed, retrieved,
 *              appended, replaced, deleted.
 * ----------------------------------------------------------------
 */
int                     NTupleProcessed;
int                     NTupleRetrieved;
int                     NTupleReplaced;
int                     NTupleAppended;
int                     NTupleDeleted;
int                     NIndexTupleInserted;
int                     NIndexTupleProcessed;


static void ShutdownExprContext(ExprContext *econtext);


/* ----------------------------------------------------------------
 *                                              statistic functions
 * ----------------------------------------------------------------
 */

/* ----------------------------------------------------------------
 *              ResetTupleCount
 * ----------------------------------------------------------------
 */
#ifdef NOT_USED
void
ResetTupleCount(void)
{
        NTupleProcessed = 0;
        NTupleRetrieved = 0;
        NTupleAppended = 0;
        NTupleDeleted = 0;
        NTupleReplaced = 0;
        NIndexTupleProcessed = 0;
}
#endif

/* ----------------------------------------------------------------
 *              PrintTupleCount
 * ----------------------------------------------------------------
 */
#ifdef NOT_USED
void
DisplayTupleCount(FILE *statfp)
{
        if (NTupleProcessed > 0)
                fprintf(statfp, "!\t%d tuple%s processed, ", NTupleProcessed,
                                (NTupleProcessed == 1) ? "" : "s");
        else
        {
                fprintf(statfp, "!\tno tuples processed.\n");
                return;
        }
        if (NIndexTupleProcessed > 0)
                fprintf(statfp, "%d indextuple%s processed, ", NIndexTupleProcessed,
                                (NIndexTupleProcessed == 1) ? "" : "s");
        if (NIndexTupleInserted > 0)
                fprintf(statfp, "%d indextuple%s inserted, ", NIndexTupleInserted,
                                (NIndexTupleInserted == 1) ? "" : "s");
        if (NTupleRetrieved > 0)
                fprintf(statfp, "%d tuple%s retrieved. ", NTupleRetrieved,
                                (NTupleRetrieved == 1) ? "" : "s");
        if (NTupleAppended > 0)
                fprintf(statfp, "%d tuple%s appended. ", NTupleAppended,
                                (NTupleAppended == 1) ? "" : "s");
        if (NTupleDeleted > 0)
                fprintf(statfp, "%d tuple%s deleted. ", NTupleDeleted,
                                (NTupleDeleted == 1) ? "" : "s");
        if (NTupleReplaced > 0)
                fprintf(statfp, "%d tuple%s replaced. ", NTupleReplaced,
                                (NTupleReplaced == 1) ? "" : "s");
        fprintf(statfp, "\n");
}
#endif


/* ----------------------------------------------------------------
 *                               Executor state and memory management functions
 * ----------------------------------------------------------------
 */

/* ----------------
 *              CreateExecutorState
 *
 *              Create and initialize an EState node, which is the root of
 *              working storage for an entire Executor invocation.
 *
 * Principally, this creates the per-query memory context that will be
 * used to hold all working data that lives till the end of the query.
 * Note that the per-query context will become a child of the caller's
 * CurrentMemoryContext.
 * ----------------
 */
EState *
CreateExecutorState(void)
{
        EState     *estate;
        MemoryContext qcontext;
        MemoryContext oldcontext;

        /*
         * Create the per-query context for this Executor run.
         */
        qcontext = AllocSetContextCreate(CurrentMemoryContext,
                                                                         "ExecutorState",
                                                                         ALLOCSET_DEFAULT_MINSIZE,
                                                                         ALLOCSET_DEFAULT_INITSIZE,
                                                                         ALLOCSET_DEFAULT_MAXSIZE);

        /*
         * Make the EState node within the per-query context.  This way, we don't
         * need a separate pfree() operation for it at shutdown.
         */
        oldcontext = MemoryContextSwitchTo(qcontext);

        estate = makeNode(EState);

        /*
         * Initialize all fields of the Executor State structure
         */
        estate->es_direction = ForwardScanDirection;
        estate->es_snapshot = SnapshotNow;
        estate->es_crosscheck_snapshot = InvalidSnapshot;       /* no crosscheck */
        estate->es_range_table = NIL;

        estate->es_output_cid = (CommandId) 0;

        estate->es_result_relations = NULL;
        estate->es_num_result_relations = 0;
        estate->es_result_relation_info = NULL;

        estate->es_junkFilter = NULL;

        estate->es_trig_target_relations = NIL;
        estate->es_trig_tuple_slot = NULL;

        estate->es_param_list_info = NULL;
        estate->es_param_exec_vals = NULL;

        estate->es_query_cxt = qcontext;

        estate->es_tupleTable = NULL;

        estate->es_processed = 0;
        estate->es_lastoid = InvalidOid;
        estate->es_rowMarks = NIL;

        estate->es_instrument = false;
        estate->es_select_into = false;
        estate->es_into_oids = false;

        estate->es_exprcontexts = NIL;

        estate->es_subplanstates = NIL;

        estate->es_per_tuple_exprcontext = NULL;

        estate->es_plannedstmt = NULL;
        estate->es_evalPlanQual = NULL;
        estate->es_evTupleNull = NULL;
        estate->es_evTuple = NULL;
        estate->es_useEvalPlan = false;

        /*
         * Return the executor state structure
         */
        MemoryContextSwitchTo(oldcontext);

        return estate;
}

/* ----------------
 *              FreeExecutorState
 *
 *              Release an EState along with all remaining working storage.
 *
 * Note: this is not responsible for releasing non-memory resources,
 * such as open relations or buffer pins.  But it will shut down any
 * still-active ExprContexts within the EState.  That is sufficient
 * cleanup for situations where the EState has only been used for expression
 * evaluation, and not to run a complete Plan.
 *
 * This can be called in any memory context ... so long as it's not one
 * of the ones to be freed.
 * ----------------
 */
void
FreeExecutorState(EState *estate)
{
        /*
         * Shut down and free any remaining ExprContexts.  We do this explicitly
         * to ensure that any remaining shutdown callbacks get called (since they
         * might need to release resources that aren't simply memory within the
         * per-query memory context).
         */
        while (estate->es_exprcontexts)
        {
                /*
                 * XXX: seems there ought to be a faster way to implement this than
                 * repeated list_delete(), no?
                 */
                FreeExprContext((ExprContext *) linitial(estate->es_exprcontexts));
                /* FreeExprContext removed the list link for us */
        }

        /*
         * Free the per-query memory context, thereby releasing all working
         * memory, including the EState node itself.
         */
        MemoryContextDelete(estate->es_query_cxt);
}

/* ----------------
 *              CreateExprContext
 *
 *              Create a context for expression evaluation within an EState.
 *
 * An executor run may require multiple ExprContexts (we usually make one
 * for each Plan node, and a separate one for per-output-tuple processing
 * such as constraint checking).  Each ExprContext has its own "per-tuple"
 * memory context.
 *
 * Note we make no assumption about the caller's memory context.
 * ----------------
 */
ExprContext *
CreateExprContext(EState *estate)
{
        ExprContext *econtext;
        MemoryContext oldcontext;

        /* Create the ExprContext node within the per-query memory context */
        oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

        econtext = makeNode(ExprContext);

        /* Initialize fields of ExprContext */
        econtext->ecxt_scantuple = NULL;
        econtext->ecxt_innertuple = NULL;
        econtext->ecxt_outertuple = NULL;

        econtext->ecxt_per_query_memory = estate->es_query_cxt;

        /*
         * Create working memory for expression evaluation in this context.
         */
        econtext->ecxt_per_tuple_memory =
                AllocSetContextCreate(estate->es_query_cxt,
                                                          "ExprContext",
                                                          ALLOCSET_DEFAULT_MINSIZE,
                                                          ALLOCSET_DEFAULT_INITSIZE,
                                                          ALLOCSET_DEFAULT_MAXSIZE);

        econtext->ecxt_param_exec_vals = estate->es_param_exec_vals;
        econtext->ecxt_param_list_info = estate->es_param_list_info;

        econtext->ecxt_aggvalues = NULL;
        econtext->ecxt_aggnulls = NULL;

        econtext->caseValue_datum = (Datum) 0;
        econtext->caseValue_isNull = true;

        econtext->domainValue_datum = (Datum) 0;
        econtext->domainValue_isNull = true;

        econtext->ecxt_estate = estate;

        econtext->ecxt_callbacks = NULL;

        /*
         * Link the ExprContext into the EState to ensure it is shut down when the
         * EState is freed.  Because we use lcons(), shutdowns will occur in
         * reverse order of creation, which may not be essential but can't hurt.
         */
        estate->es_exprcontexts = lcons(econtext, estate->es_exprcontexts);

        MemoryContextSwitchTo(oldcontext);

        return econtext;
}

/* ----------------
 *              CreateStandaloneExprContext
 *
 *              Create a context for standalone expression evaluation.
 *
 * An ExprContext made this way can be used for evaluation of expressions
 * that contain no Params, subplans, or Var references (it might work to
 * put tuple references into the scantuple field, but it seems unwise).
 *
 * The ExprContext struct is allocated in the caller's current memory
 * context, which also becomes its "per query" context.
 *
 * It is caller's responsibility to free the ExprContext when done,
 * or at least ensure that any shutdown callbacks have been called
 * (ReScanExprContext() is suitable).  Otherwise, non-memory resources
 * might be leaked.
 * ----------------
 */
ExprContext *
CreateStandaloneExprContext(void)
{
        ExprContext *econtext;

        /* Create the ExprContext node within the caller's memory context */
        econtext = makeNode(ExprContext);

        /* Initialize fields of ExprContext */
        econtext->ecxt_scantuple = NULL;
        econtext->ecxt_innertuple = NULL;
        econtext->ecxt_outertuple = NULL;

        econtext->ecxt_per_query_memory = CurrentMemoryContext;

        /*
         * Create working memory for expression evaluation in this context.
         */
        econtext->ecxt_per_tuple_memory =
                AllocSetContextCreate(CurrentMemoryContext,
                                                          "ExprContext",
                                                          ALLOCSET_DEFAULT_MINSIZE,
                                                          ALLOCSET_DEFAULT_INITSIZE,
                                                          ALLOCSET_DEFAULT_MAXSIZE);

        econtext->ecxt_param_exec_vals = NULL;
        econtext->ecxt_param_list_info = NULL;

        econtext->ecxt_aggvalues = NULL;
        econtext->ecxt_aggnulls = NULL;

        econtext->caseValue_datum = (Datum) 0;
        econtext->caseValue_isNull = true;

        econtext->domainValue_datum = (Datum) 0;
        econtext->domainValue_isNull = true;

        econtext->ecxt_estate = NULL;

        econtext->ecxt_callbacks = NULL;

        return econtext;
}

/* ----------------
 *              FreeExprContext
 *
 *              Free an expression context, including calling any remaining
 *              shutdown callbacks.
 *
 * Since we free the temporary context used for expression evaluation,
 * any previously computed pass-by-reference expression result will go away!
 *
 * Note we make no assumption about the caller's memory context.
 * ----------------
 */
void
FreeExprContext(ExprContext *econtext)
{
        EState     *estate;

        /* Call any registered callbacks */
        ShutdownExprContext(econtext);
        /* And clean up the memory used */
        MemoryContextDelete(econtext->ecxt_per_tuple_memory);
        /* Unlink self from owning EState, if any */
        estate = econtext->ecxt_estate;
        if (estate)
                estate->es_exprcontexts = list_delete_ptr(estate->es_exprcontexts,
                                                                                                  econtext);
        /* And delete the ExprContext node */
        pfree(econtext);
}

/*
 * ReScanExprContext
 *
 *              Reset an expression context in preparation for a rescan of its
 *              plan node.      This requires calling any registered shutdown callbacks,
 *              since any partially complete set-returning-functions must be canceled.
 *
 * Note we make no assumption about the caller's memory context.
 */
void
ReScanExprContext(ExprContext *econtext)
{
        /* Call any registered callbacks */
        ShutdownExprContext(econtext);
        /* And clean up the memory used */
        MemoryContextReset(econtext->ecxt_per_tuple_memory);
}

/*
 * Build a per-output-tuple ExprContext for an EState.
 *
 * This is normally invoked via GetPerTupleExprContext() macro,
 * not directly.
 */
ExprContext *
MakePerTupleExprContext(EState *estate)
{
        if (estate->es_per_tuple_exprcontext == NULL)
                estate->es_per_tuple_exprcontext = CreateExprContext(estate);

        return estate->es_per_tuple_exprcontext;
}


/* ----------------------------------------------------------------
 *                               miscellaneous node-init support functions
 *
 * Note: all of these are expected to be called with CurrentMemoryContext
 * equal to the per-query memory context.
 * ----------------------------------------------------------------
 */

/* ----------------
 *              ExecAssignExprContext
 *
 *              This initializes the ps_ExprContext field.      It is only necessary
 *              to do this for nodes which use ExecQual or ExecProject
 *              because those routines require an econtext. Other nodes that
 *              don't have to evaluate expressions don't need to do this.
 * ----------------
 */
void
ExecAssignExprContext(EState *estate, PlanState *planstate)
{
        planstate->ps_ExprContext = CreateExprContext(estate);
}

/* ----------------
 *              ExecAssignResultType
 * ----------------
 */
void
ExecAssignResultType(PlanState *planstate, TupleDesc tupDesc)
{
        TupleTableSlot *slot = planstate->ps_ResultTupleSlot;

        ExecSetSlotDescriptor(slot, tupDesc);
}

/* ----------------
 *              ExecAssignResultTypeFromTL
 * ----------------
 */
void
ExecAssignResultTypeFromTL(PlanState *planstate)
{
        bool            hasoid;
        TupleDesc       tupDesc;

        if (ExecContextForcesOids(planstate, &hasoid))
        {
                /* context forces OID choice; hasoid is now set correctly */
        }
        else
        {
                /* given free choice, don't leave space for OIDs in result tuples */
                hasoid = false;
        }

        /*
         * ExecTypeFromTL needs the parse-time representation of the tlist, not a
         * list of ExprStates.  This is good because some plan nodes don't bother
         * to set up planstate->targetlist ...
         */
        tupDesc = ExecTypeFromTL(planstate->plan->targetlist, hasoid);
        ExecAssignResultType(planstate, tupDesc);
}

/* ----------------
 *              ExecGetResultType
 * ----------------
 */
TupleDesc
ExecGetResultType(PlanState *planstate)
{
        TupleTableSlot *slot = planstate->ps_ResultTupleSlot;

        return slot->tts_tupleDescriptor;
}

/* ----------------
 *              ExecBuildProjectionInfo
 *
 * Build a ProjectionInfo node for evaluating the given tlist in the given
 * econtext, and storing the result into the tuple slot.  (Caller must have
 * ensured that tuple slot has a descriptor matching the tlist!)  Note that
 * the given tlist should be a list of ExprState nodes, not Expr nodes.
 *
 * inputDesc can be NULL, but if it is not, we check to see whether simple
 * Vars in the tlist match the descriptor.      It is important to provide
 * inputDesc for relation-scan plan nodes, as a cross check that the relation
 * hasn't been changed since the plan was made.  At higher levels of a plan,
 * there is no need to recheck.
 * ----------------
 */
ProjectionInfo *
ExecBuildProjectionInfo(List *targetList,
                                                ExprContext *econtext,
                                                TupleTableSlot *slot,
                                                TupleDesc inputDesc)
{
        ProjectionInfo *projInfo = makeNode(ProjectionInfo);
        int                     len;
        bool            isVarList;
        ListCell   *tl;

        len = ExecTargetListLength(targetList);

        projInfo->pi_targetlist = targetList;
        projInfo->pi_exprContext = econtext;
        projInfo->pi_slot = slot;

        /*
         * Determine whether the target list consists entirely of simple Var
         * references (ie, references to non-system attributes) that match the
         * input.  If so, we can use the simpler ExecVariableList instead of
         * ExecTargetList.      (Note: if there is a type mismatch then ExecEvalVar
         * will probably throw an error at runtime, but we leave that to it.)
         */
        isVarList = true;
        foreach(tl, targetList)
        {
                GenericExprState *gstate = (GenericExprState *) lfirst(tl);
                Var                *variable = (Var *) gstate->arg->expr;
                Form_pg_attribute attr;

                if (variable == NULL ||
                        !IsA(variable, Var) ||
                        variable->varattno <= 0)
                {
                        isVarList = false;
                        break;
                }
                if (!inputDesc)
                        continue;                       /* can't check type, assume OK */
                if (variable->varattno > inputDesc->natts)
                {
                        isVarList = false;
                        break;
                }
                attr = inputDesc->attrs[variable->varattno - 1];
                if (attr->attisdropped || variable->vartype != attr->atttypid)
                {
                        isVarList = false;
                        break;
                }
        }
        projInfo->pi_isVarList = isVarList;

        if (isVarList)
        {
                int                *varSlotOffsets;
                int                *varNumbers;
                AttrNumber      lastInnerVar = 0;
                AttrNumber      lastOuterVar = 0;
                AttrNumber      lastScanVar = 0;

                projInfo->pi_itemIsDone = NULL; /* not needed */
                projInfo->pi_varSlotOffsets = varSlotOffsets = (int *)
                        palloc0(len * sizeof(int));
                projInfo->pi_varNumbers = varNumbers = (int *)
                        palloc0(len * sizeof(int));

                /*
                 * Set up the data needed by ExecVariableList.  The slots in which the
                 * variables can be found at runtime are denoted by the offsets of
                 * their slot pointers within the econtext.  This rather grotty
                 * representation is needed because the caller may not have given us
                 * the real econtext yet (see hacks in nodeSubplan.c).
                 */
                foreach(tl, targetList)
                {
                        GenericExprState *gstate = (GenericExprState *) lfirst(tl);
                        Var                *variable = (Var *) gstate->arg->expr;
                        AttrNumber      attnum = variable->varattno;
                        TargetEntry *tle = (TargetEntry *) gstate->xprstate.expr;
                        AttrNumber      resind = tle->resno - 1;

                        Assert(resind >= 0 && resind < len);
                        varNumbers[resind] = attnum;

                        switch (variable->varno)
                        {
                                case INNER:
                                        varSlotOffsets[resind] = offsetof(ExprContext,
                                                                                                          ecxt_innertuple);
                                        lastInnerVar = Max(lastInnerVar, attnum);
                                        break;

                                case OUTER:
                                        varSlotOffsets[resind] = offsetof(ExprContext,
                                                                                                          ecxt_outertuple);
                                        lastOuterVar = Max(lastOuterVar, attnum);
                                        break;

                                default:
                                        varSlotOffsets[resind] = offsetof(ExprContext,
                                                                                                          ecxt_scantuple);
                                        lastScanVar = Max(lastScanVar, attnum);
                                        break;
                        }
                }
                projInfo->pi_lastInnerVar = lastInnerVar;
                projInfo->pi_lastOuterVar = lastOuterVar;
                projInfo->pi_lastScanVar = lastScanVar;
        }
        else
        {
                projInfo->pi_itemIsDone = (ExprDoneCond *)
                        palloc(len * sizeof(ExprDoneCond));
                projInfo->pi_varSlotOffsets = NULL;
                projInfo->pi_varNumbers = NULL;
        }

        return projInfo;
}

/* ----------------
 *              ExecAssignProjectionInfo
 *
 * forms the projection information from the node's targetlist
 *
 * Notes for inputDesc are same as for ExecBuildProjectionInfo: supply it
 * for a relation-scan node, can pass NULL for upper-level nodes
 * ----------------
 */
void
ExecAssignProjectionInfo(PlanState *planstate,
                                                 TupleDesc inputDesc)
{
        planstate->ps_ProjInfo =
                ExecBuildProjectionInfo(planstate->targetlist,
                                                                planstate->ps_ExprContext,
                                                                planstate->ps_ResultTupleSlot,
                                                                inputDesc);
}


/* ----------------
 *              ExecFreeExprContext
 *
 * A plan node's ExprContext should be freed explicitly during executor
 * shutdown because there may be shutdown callbacks to call.  (Other resources
 * made by the above routines, such as projection info, don't need to be freed
 * explicitly because they're just memory in the per-query memory context.)
 *
 * However ... there is no particular need to do it during ExecEndNode,
 * because FreeExecutorState will free any remaining ExprContexts within
 * the EState.  Letting FreeExecutorState do it allows the ExprContexts to
 * be freed in reverse order of creation, rather than order of creation as
 * will happen if we delete them here, which saves O(N^2) work in the list
 * cleanup inside FreeExprContext.
 * ----------------
 */
void
ExecFreeExprContext(PlanState *planstate)
{
        /*
         * Per above discussion, don't actually delete the ExprContext. We do
         * unlink it from the plan node, though.
         */
        planstate->ps_ExprContext = NULL;
}

/* ----------------------------------------------------------------
 *              the following scan type support functions are for
 *              those nodes which are stubborn and return tuples in
 *              their Scan tuple slot instead of their Result tuple
 *              slot..  luck fur us, these nodes do not do projections
 *              so we don't have to worry about getting the ProjectionInfo
 *              right for them...  -cim 6/3/91
 * ----------------------------------------------------------------
 */

/* ----------------
 *              ExecGetScanType
 * ----------------
 */
TupleDesc
ExecGetScanType(ScanState *scanstate)
{
        TupleTableSlot *slot = scanstate->ss_ScanTupleSlot;

        return slot->tts_tupleDescriptor;
}

/* ----------------
 *              ExecAssignScanType
 * ----------------
 */
void
ExecAssignScanType(ScanState *scanstate, TupleDesc tupDesc)
{
        TupleTableSlot *slot = scanstate->ss_ScanTupleSlot;

        ExecSetSlotDescriptor(slot, tupDesc);
}

/* ----------------
 *              ExecAssignScanTypeFromOuterPlan
 * ----------------
 */
void
ExecAssignScanTypeFromOuterPlan(ScanState *scanstate)
{
        PlanState  *outerPlan;
        TupleDesc       tupDesc;

        outerPlan = outerPlanState(scanstate);
        tupDesc = ExecGetResultType(outerPlan);

        ExecAssignScanType(scanstate, tupDesc);
}


/* ----------------------------------------------------------------
 *                                Scan node support
 * ----------------------------------------------------------------
 */

/* ----------------------------------------------------------------
 *              ExecRelationIsTargetRelation
 *
 *              Detect whether a relation (identified by rangetable index)
 *              is one of the target relations of the query.
 * ----------------------------------------------------------------
 */
bool
ExecRelationIsTargetRelation(EState *estate, Index scanrelid)
{
        ResultRelInfo *resultRelInfos;
        int                     i;

        resultRelInfos = estate->es_result_relations;
        for (i = 0; i < estate->es_num_result_relations; i++)
        {
                if (resultRelInfos[i].ri_RangeTableIndex == scanrelid)
                        return true;
        }
        return false;
}

/* ----------------------------------------------------------------
 *              ExecOpenScanRelation
 *
 *              Open the heap relation to be scanned by a base-level scan plan node.
 *              This should be called during the node's ExecInit routine.
 *
 * By default, this acquires AccessShareLock on the relation.  However,
 * if the relation was already locked by InitPlan, we don't need to acquire
 * any additional lock.  This saves trips to the shared lock manager.
 * ----------------------------------------------------------------
 */
Relation
ExecOpenScanRelation(EState *estate, Index scanrelid)
{
        Oid                     reloid;
        LOCKMODE        lockmode;

        /*
         * Determine the lock type we need.  First, scan to see if target relation
         * is a result relation.  If not, check if it's a FOR UPDATE/FOR SHARE
         * relation.  In either of those cases, we got the lock already.
         */
        lockmode = AccessShareLock;
        if (ExecRelationIsTargetRelation(estate, scanrelid))
                lockmode = NoLock;
        else
        {
                ListCell   *l;

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

                        if (erm->rti == scanrelid)
                        {
                                lockmode = NoLock;
                                break;
                        }
                }
        }

        /* OK, open the relation and acquire lock as needed */
        reloid = getrelid(scanrelid, estate->es_range_table);
        return heap_open(reloid, lockmode);
}

/* ----------------------------------------------------------------
 *              ExecCloseScanRelation
 *
 *              Close the heap relation scanned by a base-level scan plan node.
 *              This should be called during the node's ExecEnd routine.
 *
 * Currently, we do not release the lock acquired by ExecOpenScanRelation.
 * This lock should be held till end of transaction.  (There is a faction
 * that considers this too much locking, however.)
 *
 * If we did want to release the lock, we'd have to repeat the logic in
 * ExecOpenScanRelation in order to figure out what to release.
 * ----------------------------------------------------------------
 */
void
ExecCloseScanRelation(Relation scanrel)
{
        heap_close(scanrel, NoLock);
}


/* ----------------------------------------------------------------
 *                                ExecInsertIndexTuples support
 * ----------------------------------------------------------------
 */

/* ----------------------------------------------------------------
 *              ExecOpenIndices
 *
 *              Find the indices associated with a result relation, open them,
 *              and save information about them in the result ResultRelInfo.
 *
 *              At entry, caller has already opened and locked
 *              resultRelInfo->ri_RelationDesc.
 * ----------------------------------------------------------------
 */
void
ExecOpenIndices(ResultRelInfo *resultRelInfo)
{
        Relation        resultRelation = resultRelInfo->ri_RelationDesc;
        List       *indexoidlist;
        ListCell   *l;
        int                     len,
                                i;
        RelationPtr relationDescs;
        IndexInfo **indexInfoArray;

        resultRelInfo->ri_NumIndices = 0;

        /* fast path if no indexes */
        if (!RelationGetForm(resultRelation)->relhasindex)
                return;

        /*
         * Get cached list of index OIDs
         */
        indexoidlist = RelationGetIndexList(resultRelation);
        len = list_length(indexoidlist);
        if (len == 0)
                return;

        /*
         * allocate space for result arrays
         */
        relationDescs = (RelationPtr) palloc(len * sizeof(Relation));
        indexInfoArray = (IndexInfo **) palloc(len * sizeof(IndexInfo *));

        resultRelInfo->ri_NumIndices = len;
        resultRelInfo->ri_IndexRelationDescs = relationDescs;
        resultRelInfo->ri_IndexRelationInfo = indexInfoArray;

        /*
         * For each index, open the index relation and save pg_index info. We
         * acquire RowExclusiveLock, signifying we will update the index.
         */
        i = 0;
        foreach(l, indexoidlist)
        {
                Oid                     indexOid = lfirst_oid(l);
                Relation        indexDesc;
                IndexInfo  *ii;

                indexDesc = index_open(indexOid, RowExclusiveLock);

                /* extract index key information from the index's pg_index info */
                ii = BuildIndexInfo(indexDesc);

                relationDescs[i] = indexDesc;
                indexInfoArray[i] = ii;
                i++;
        }

        list_free(indexoidlist);
}

/* ----------------------------------------------------------------
 *              ExecCloseIndices
 *
 *              Close the index relations stored in resultRelInfo
 * ----------------------------------------------------------------
 */
void
ExecCloseIndices(ResultRelInfo *resultRelInfo)
{
        int                     i;
        int                     numIndices;
        RelationPtr indexDescs;

        numIndices = resultRelInfo->ri_NumIndices;
        indexDescs = resultRelInfo->ri_IndexRelationDescs;

        for (i = 0; i < numIndices; i++)
        {
                if (indexDescs[i] == NULL)
                        continue;                       /* shouldn't happen? */

                /* Drop lock acquired by ExecOpenIndices */
                index_close(indexDescs[i], RowExclusiveLock);
        }

        /*
         * XXX should free indexInfo array here too?  Currently we assume that
         * such stuff will be cleaned up automatically in FreeExecutorState.
         */
}

/* ----------------------------------------------------------------
 *              ExecInsertIndexTuples
 *
 *              This routine takes care of inserting index tuples
 *              into all the relations indexing the result relation
 *              when a heap tuple is inserted into the result relation.
 *              Much of this code should be moved into the genam
 *              stuff as it only exists here because the genam stuff
 *              doesn't provide the functionality needed by the
 *              executor.. -cim 9/27/89
 *
 *              CAUTION: this must not be called for a HOT update.
 *              We can't defend against that here for lack of info.
 *              Should we change the API to make it safer?
 * ----------------------------------------------------------------
 */
void
ExecInsertIndexTuples(TupleTableSlot *slot,
                                          ItemPointer tupleid,
                                          EState *estate,
                                          bool is_vacuum)
{
        ResultRelInfo *resultRelInfo;
        int                     i;
        int                     numIndices;
        RelationPtr relationDescs;
        Relation        heapRelation;
        IndexInfo **indexInfoArray;
        ExprContext *econtext;
        Datum           values[INDEX_MAX_KEYS];
        bool            isnull[INDEX_MAX_KEYS];

        /*
         * Get information from the result relation info structure.
         */
        resultRelInfo = estate->es_result_relation_info;
        numIndices = resultRelInfo->ri_NumIndices;
        relationDescs = resultRelInfo->ri_IndexRelationDescs;
        indexInfoArray = resultRelInfo->ri_IndexRelationInfo;
        heapRelation = resultRelInfo->ri_RelationDesc;

        /*
         * We will use the EState's per-tuple context for evaluating predicates
         * and index 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;

        /*
         * for each index, form and insert the index tuple
         */
        for (i = 0; i < numIndices; i++)
        {
                IndexInfo  *indexInfo;

                if (relationDescs[i] == NULL)
                        continue;

                indexInfo = indexInfoArray[i];

                /* If the index is marked as read-only, ignore it */
                if (!indexInfo->ii_ReadyForInserts)
                        continue;

                /* Check for partial index */
                if (indexInfo->ii_Predicate != NIL)
                {
                        List       *predicate;

                        /*
                         * If predicate state not set up yet, create it (in the estate's
                         * per-query context)
                         */
                        predicate = indexInfo->ii_PredicateState;
                        if (predicate == NIL)
                        {
                                predicate = (List *)
                                        ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
                                                                        estate);
                                indexInfo->ii_PredicateState = predicate;
                        }

                        /* Skip this index-update if the predicate isn't satisfied */
                        if (!ExecQual(predicate, econtext, false))
                                continue;
                }

                /*
                 * FormIndexDatum fills in its values and isnull parameters with the
                 * appropriate values for the column(s) of the index.
                 */
                FormIndexDatum(indexInfo,
                                           slot,
                                           estate,
                                           values,
                                           isnull);

                /*
                 * The index AM does the rest.  Note we suppress unique-index checks
                 * if we are being called from VACUUM, since VACUUM may need to move
                 * dead tuples that have the same keys as live ones.
                 */
                index_insert(relationDescs[i],  /* index relation */
                                         values,        /* array of index Datums */
                                         isnull,        /* null flags */
                                         tupleid,       /* tid of heap tuple */
                                         heapRelation,
                                         relationDescs[i]->rd_index->indisunique && !is_vacuum);

                /*
                 * keep track of index inserts for debugging
                 */
                IncrIndexInserted();
        }
}

/*
 * UpdateChangedParamSet
 *              Add changed parameters to a plan node's chgParam set
 */
void
UpdateChangedParamSet(PlanState *node, Bitmapset *newchg)
{
        Bitmapset  *parmset;

        /*
         * The plan node only depends on params listed in its allParam set. Don't
         * include anything else into its chgParam set.
         */
        parmset = bms_intersect(node->plan->allParam, newchg);

        /*
         * Keep node->chgParam == NULL if there's not actually any members; this
         * allows the simplest possible tests in executor node files.
         */
        if (!bms_is_empty(parmset))
                node->chgParam = bms_join(node->chgParam, parmset);
        else
                bms_free(parmset);
}

/*
 * Register a shutdown callback in an ExprContext.
 *
 * Shutdown callbacks will be called (in reverse order of registration)
 * when the ExprContext is deleted or rescanned.  This provides a hook
 * for functions called in the context to do any cleanup needed --- it's
 * particularly useful for functions returning sets.  Note that the
 * callback will *not* be called in the event that execution is aborted
 * by an error.
 */
void
RegisterExprContextCallback(ExprContext *econtext,
                                                        ExprContextCallbackFunction function,
                                                        Datum arg)
{
        ExprContext_CB *ecxt_callback;

        /* Save the info in appropriate memory context */
        ecxt_callback = (ExprContext_CB *)
                MemoryContextAlloc(econtext->ecxt_per_query_memory,
                                                   sizeof(ExprContext_CB));

        ecxt_callback->function = function;
        ecxt_callback->arg = arg;

        /* link to front of list for appropriate execution order */
        ecxt_callback->next = econtext->ecxt_callbacks;
        econtext->ecxt_callbacks = ecxt_callback;
}

/*
 * Deregister a shutdown callback in an ExprContext.
 *
 * Any list entries matching the function and arg will be removed.
 * This can be used if it's no longer necessary to call the callback.
 */
void
UnregisterExprContextCallback(ExprContext *econtext,
                                                          ExprContextCallbackFunction function,
                                                          Datum arg)
{
        ExprContext_CB **prev_callback;
        ExprContext_CB *ecxt_callback;

        prev_callback = &econtext->ecxt_callbacks;

        while ((ecxt_callback = *prev_callback) != NULL)
        {
                if (ecxt_callback->function == function && ecxt_callback->arg == arg)
                {
                        *prev_callback = ecxt_callback->next;
                        pfree(ecxt_callback);
                }
                else
                        prev_callback = &ecxt_callback->next;
        }
}

/*
 * Call all the shutdown callbacks registered in an ExprContext.
 *
 * The callback list is emptied (important in case this is only a rescan
 * reset, and not deletion of the ExprContext).
 */
static void
ShutdownExprContext(ExprContext *econtext)
{
        ExprContext_CB *ecxt_callback;
        MemoryContext oldcontext;

        /* Fast path in normal case where there's nothing to do. */
        if (econtext->ecxt_callbacks == NULL)
                return;

        /*
         * Call the callbacks in econtext's per-tuple context.  This ensures that
         * any memory they might leak will get cleaned up.
         */
        oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);

        /*
         * Call each callback function in reverse registration order.
         */
        while ((ecxt_callback = econtext->ecxt_callbacks) != NULL)
        {
                econtext->ecxt_callbacks = ecxt_callback->next;
                (*ecxt_callback->function) (ecxt_callback->arg);
                pfree(ecxt_callback);
        }

        MemoryContextSwitchTo(oldcontext);
}