granicus.if.org Git - postgresql/blob - src/backend/executor/execMain.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * execMain.c
   4  *        top level executor interface routines
   5  *
   6  * INTERFACE ROUTINES
   7  *      ExecutorStart()
   8  *      ExecutorRun()
   9  *      ExecutorEnd()
  10  *
  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),
  12  *      ExecutorRun() and ExecutorEnd()
  13  *
  14  *      These three procedures are the external interfaces to the executor.
  15  *      In each case, the query descriptor is required as an argument.
  16  *
  17  *      ExecutorStart() must be called at the beginning of execution of any
  18  *      query plan and ExecutorEnd() should always be called at the end of
  19  *      execution of a plan.
  20  *
  21  *      ExecutorRun accepts direction and count arguments that specify whether
  22  *      the plan is to be executed forwards, backwards, and for how many tuples.
  23  *
  24  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  25  * Portions Copyright (c) 1994, Regents of the University of California
  26  *
  27  *
  28  * IDENTIFICATION
  29  *        $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.252 2005/08/01 20:31:07 tgl Exp $
  30  *
  31  *-------------------------------------------------------------------------
  32  */
  33 #include "postgres.h"
  34
  35 #include "access/heapam.h"
  36 #include "access/xlog.h"
  37 #include "catalog/heap.h"
  38 #include "catalog/namespace.h"
  39 #include "commands/tablecmds.h"
  40 #include "commands/trigger.h"
  41 #include "executor/execdebug.h"
  42 #include "executor/execdefs.h"
  43 #include "executor/instrument.h"
  44 #include "miscadmin.h"
  45 #include "optimizer/clauses.h"
  46 #include "optimizer/var.h"
  47 #include "parser/parsetree.h"
  48 #include "storage/smgr.h"
  49 #include "utils/acl.h"
  50 #include "utils/guc.h"
  51 #include "utils/lsyscache.h"
  52 #include "utils/memutils.h"
  53
  54
  55 typedef struct execRowMark
  56 {
  57         Relation        relation;
  58         Index           rti;
  59         char            resname[32];
  60 } execRowMark;
  61
  62 typedef struct evalPlanQual
  63 {
  64         Index           rti;
  65         EState     *estate;
  66         PlanState  *planstate;
  67         struct evalPlanQual *next;      /* stack of active PlanQual plans */
  68         struct evalPlanQual *free;      /* list of free PlanQual plans */
  69 } evalPlanQual;
  70
  71 /* decls for local routines only used within this module */
  72 static void InitPlan(QueryDesc *queryDesc, bool explainOnly);
  73 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  74                                   Index resultRelationIndex,
  75                                   List *rangeTable,
  76                                   CmdType operation,
  77                                   bool doInstrument);
  78 static TupleTableSlot *ExecutePlan(EState *estate, PlanState *planstate,
  79                         CmdType operation,
  80                         long numberTuples,
  81                         ScanDirection direction,
  82                         DestReceiver *dest);
  83 static void ExecSelect(TupleTableSlot *slot,
  84                    DestReceiver *dest,
  85                    EState *estate);
  86 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  87                    EState *estate);
  88 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  89                    EState *estate);
  90 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  91                    EState *estate);
  92 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  93 static void EndEvalPlanQual(EState *estate);
  94 static void ExecCheckRTEPerms(RangeTblEntry *rte);
  95 static void ExecCheckXactReadOnly(Query *parsetree);
  96 static void EvalPlanQualStart(evalPlanQual *epq, EState *estate,
  97                                   evalPlanQual *priorepq);
  98 static void EvalPlanQualStop(evalPlanQual *epq);
  99
 100 /* end of local decls */
 101
 102
 103 /* ----------------------------------------------------------------
 104  *              ExecutorStart
 105  *
 106  *              This routine must be called at the beginning of any execution of any
 107  *              query plan
 108  *
 109  * Takes a QueryDesc previously created by CreateQueryDesc (it's not real
 110  * clear why we bother to separate the two functions, but...).  The tupDesc
 111  * field of the QueryDesc is filled in to describe the tuples that will be
 112  * returned, and the internal fields (estate and planstate) are set up.
 113  *
 114  * If explainOnly is true, we are not actually intending to run the plan,
 115  * only to set up for EXPLAIN; so skip unwanted side-effects.
 116  *
 117  * NB: the CurrentMemoryContext when this is called will become the parent
 118  * of the per-query context used for this Executor invocation.
 119  * ----------------------------------------------------------------
 120  */
 121 void
 122 ExecutorStart(QueryDesc *queryDesc, bool explainOnly)
 123 {
 124         EState     *estate;
 125         MemoryContext oldcontext;
 126
 127         /* sanity checks: queryDesc must not be started already */
 128         Assert(queryDesc != NULL);
 129         Assert(queryDesc->estate == NULL);
 130
 131         /*
 132          * If the transaction is read-only, we need to check if any writes are
 133          * planned to non-temporary tables.
 134          */
 135         if (XactReadOnly && !explainOnly)
 136                 ExecCheckXactReadOnly(queryDesc->parsetree);
 137
 138         /*
 139          * Build EState, switch into per-query memory context for startup.
 140          */
 141         estate = CreateExecutorState();
 142         queryDesc->estate = estate;
 143
 144         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 145
 146         /*
 147          * Fill in parameters, if any, from queryDesc
 148          */
 149         estate->es_param_list_info = queryDesc->params;
 150
 151         if (queryDesc->plantree->nParamExec > 0)
 152                 estate->es_param_exec_vals = (ParamExecData *)
 153                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 154
 155         /*
 156          * Copy other important information into the EState
 157          */
 158         estate->es_snapshot = queryDesc->snapshot;
 159         estate->es_crosscheck_snapshot = queryDesc->crosscheck_snapshot;
 160         estate->es_instrument = queryDesc->doInstrument;
 161
 162         /*
 163          * Initialize the plan state tree
 164          */
 165         InitPlan(queryDesc, explainOnly);
 166
 167         MemoryContextSwitchTo(oldcontext);
 168 }
 169
 170 /* ----------------------------------------------------------------
 171  *              ExecutorRun
 172  *
 173  *              This is the main routine of the executor module. It accepts
 174  *              the query descriptor from the traffic cop and executes the
 175  *              query plan.
 176  *
 177  *              ExecutorStart must have been called already.
 178  *
 179  *              If direction is NoMovementScanDirection then nothing is done
 180  *              except to start up/shut down the destination.  Otherwise,
 181  *              we retrieve up to 'count' tuples in the specified direction.
 182  *
 183  *              Note: count = 0 is interpreted as no portal limit, i.e., run to
 184  *              completion.
 185  *
 186  * ----------------------------------------------------------------
 187  */
 188 TupleTableSlot *
 189 ExecutorRun(QueryDesc *queryDesc,
 190                         ScanDirection direction, long count)
 191 {
 192         EState     *estate;
 193         CmdType         operation;
 194         DestReceiver *dest;
 195         TupleTableSlot *result;
 196         MemoryContext oldcontext;
 197
 198         /* sanity checks */
 199         Assert(queryDesc != NULL);
 200
 201         estate = queryDesc->estate;
 202
 203         Assert(estate != NULL);
 204
 205         /*
 206          * Switch into per-query memory context
 207          */
 208         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 209
 210         /*
 211          * extract information from the query descriptor and the query
 212          * feature.
 213          */
 214         operation = queryDesc->operation;
 215         dest = queryDesc->dest;
 216
 217         /*
 218          * startup tuple receiver
 219          */
 220         estate->es_processed = 0;
 221         estate->es_lastoid = InvalidOid;
 222
 223         (*dest->rStartup) (dest, operation, queryDesc->tupDesc);
 224
 225         /*
 226          * run plan
 227          */
 228         if (direction == NoMovementScanDirection)
 229                 result = NULL;
 230         else
 231                 result = ExecutePlan(estate,
 232                                                          queryDesc->planstate,
 233                                                          operation,
 234                                                          count,
 235                                                          direction,
 236                                                          dest);
 237
 238         /*
 239          * shutdown receiver
 240          */
 241         (*dest->rShutdown) (dest);
 242
 243         MemoryContextSwitchTo(oldcontext);
 244
 245         return result;
 246 }
 247
 248 /* ----------------------------------------------------------------
 249  *              ExecutorEnd
 250  *
 251  *              This routine must be called at the end of execution of any
 252  *              query plan
 253  * ----------------------------------------------------------------
 254  */
 255 void
 256 ExecutorEnd(QueryDesc *queryDesc)
 257 {
 258         EState     *estate;
 259         MemoryContext oldcontext;
 260
 261         /* sanity checks */
 262         Assert(queryDesc != NULL);
 263
 264         estate = queryDesc->estate;
 265
 266         Assert(estate != NULL);
 267
 268         /*
 269          * Switch into per-query memory context to run ExecEndPlan
 270          */
 271         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 272
 273         ExecEndPlan(queryDesc->planstate, estate);
 274
 275         /*
 276          * Must switch out of context before destroying it
 277          */
 278         MemoryContextSwitchTo(oldcontext);
 279
 280         /*
 281          * Release EState and per-query memory context.  This should release
 282          * everything the executor has allocated.
 283          */
 284         FreeExecutorState(estate);
 285
 286         /* Reset queryDesc fields that no longer point to anything */
 287         queryDesc->tupDesc = NULL;
 288         queryDesc->estate = NULL;
 289         queryDesc->planstate = NULL;
 290 }
 291
 292 /* ----------------------------------------------------------------
 293  *              ExecutorRewind
 294  *
 295  *              This routine may be called on an open queryDesc to rewind it
 296  *              to the start.
 297  * ----------------------------------------------------------------
 298  */
 299 void
 300 ExecutorRewind(QueryDesc *queryDesc)
 301 {
 302         EState     *estate;
 303         MemoryContext oldcontext;
 304
 305         /* sanity checks */
 306         Assert(queryDesc != NULL);
 307
 308         estate = queryDesc->estate;
 309
 310         Assert(estate != NULL);
 311
 312         /* It's probably not sensible to rescan updating queries */
 313         Assert(queryDesc->operation == CMD_SELECT);
 314
 315         /*
 316          * Switch into per-query memory context
 317          */
 318         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 319
 320         /*
 321          * rescan plan
 322          */
 323         ExecReScan(queryDesc->planstate, NULL);
 324
 325         MemoryContextSwitchTo(oldcontext);
 326 }
 327
 328
 329 /*
 330  * ExecCheckRTPerms
 331  *              Check access permissions for all relations listed in a range table.
 332  */
 333 void
 334 ExecCheckRTPerms(List *rangeTable)
 335 {
 336         ListCell   *l;
 337
 338         foreach(l, rangeTable)
 339         {
 340                 RangeTblEntry *rte = lfirst(l);
 341
 342                 ExecCheckRTEPerms(rte);
 343         }
 344 }
 345
 346 /*
 347  * ExecCheckRTEPerms
 348  *              Check access permissions for a single RTE.
 349  */
 350 static void
 351 ExecCheckRTEPerms(RangeTblEntry *rte)
 352 {
 353         AclMode         requiredPerms;
 354         Oid                     relOid;
 355         Oid             userid;
 356
 357         /*
 358          * Only plain-relation RTEs need to be checked here.  Subquery RTEs
 359          * are checked by ExecInitSubqueryScan if the subquery is still a
 360          * separate subquery --- if it's been pulled up into our query level
 361          * then the RTEs are in our rangetable and will be checked here.
 362          * Function RTEs are checked by init_fcache when the function is
 363          * prepared for execution. Join and special RTEs need no checks.
 364          */
 365         if (rte->rtekind != RTE_RELATION)
 366                 return;
 367
 368         /*
 369          * No work if requiredPerms is empty.
 370          */
 371         requiredPerms = rte->requiredPerms;
 372         if (requiredPerms == 0)
 373                 return;
 374
 375         relOid = rte->relid;
 376
 377         /*
 378          * userid to check as: current user unless we have a setuid
 379          * indication.
 380          *
 381          * Note: GetUserId() is presently fast enough that there's no harm in
 382          * calling it separately for each RTE.  If that stops being true, we
 383          * could call it once in ExecCheckRTPerms and pass the userid down
 384          * from there.  But for now, no need for the extra clutter.
 385          */
 386         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 387
 388         /*
 389          * We must have *all* the requiredPerms bits, so use aclmask not
 390          * aclcheck.
 391          */
 392         if (pg_class_aclmask(relOid, userid, requiredPerms, ACLMASK_ALL)
 393                 != requiredPerms)
 394                 aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_CLASS,
 395                                            get_rel_name(relOid));
 396 }
 397
 398 /*
 399  * Check that the query does not imply any writes to non-temp tables.
 400  */
 401 static void
 402 ExecCheckXactReadOnly(Query *parsetree)
 403 {
 404         ListCell   *l;
 405
 406         /*
 407          * CREATE TABLE AS or SELECT INTO?
 408          *
 409          * XXX should we allow this if the destination is temp?
 410          */
 411         if (parsetree->into != NULL)
 412                 goto fail;
 413
 414         /* Fail if write permissions are requested on any non-temp table */
 415         foreach(l, parsetree->rtable)
 416         {
 417                 RangeTblEntry *rte = lfirst(l);
 418
 419                 if (rte->rtekind == RTE_SUBQUERY)
 420                 {
 421                         ExecCheckXactReadOnly(rte->subquery);
 422                         continue;
 423                 }
 424
 425                 if (rte->rtekind != RTE_RELATION)
 426                         continue;
 427
 428                 if ((rte->requiredPerms & (~ACL_SELECT)) == 0)
 429                         continue;
 430
 431                 if (isTempNamespace(get_rel_namespace(rte->relid)))
 432                         continue;
 433
 434                 goto fail;
 435         }
 436
 437         return;
 438
 439 fail:
 440         ereport(ERROR,
 441                         (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
 442                          errmsg("transaction is read-only")));
 443 }
 444
 445
 446 /* ----------------------------------------------------------------
 447  *              InitPlan
 448  *
 449  *              Initializes the query plan: open files, allocate storage
 450  *              and start up the rule manager
 451  * ----------------------------------------------------------------
 452  */
 453 static void
 454 InitPlan(QueryDesc *queryDesc, bool explainOnly)
 455 {
 456         CmdType         operation = queryDesc->operation;
 457         Query      *parseTree = queryDesc->parsetree;
 458         Plan       *plan = queryDesc->plantree;
 459         EState     *estate = queryDesc->estate;
 460         PlanState  *planstate;
 461         List       *rangeTable;
 462         Relation        intoRelationDesc;
 463         bool            do_select_into;
 464         TupleDesc       tupType;
 465
 466         /*
 467          * Do permissions checks.  It's sufficient to examine the query's top
 468          * rangetable here --- subplan RTEs will be checked during
 469          * ExecInitSubPlan().
 470          */
 471         ExecCheckRTPerms(parseTree->rtable);
 472
 473         /*
 474          * get information from query descriptor
 475          */
 476         rangeTable = parseTree->rtable;
 477
 478         /*
 479          * initialize the node's execution state
 480          */
 481         estate->es_range_table = rangeTable;
 482
 483         /*
 484          * if there is a result relation, initialize result relation stuff
 485          */
 486         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 487         {
 488                 List       *resultRelations = parseTree->resultRelations;
 489                 int                     numResultRelations;
 490                 ResultRelInfo *resultRelInfos;
 491
 492                 if (resultRelations != NIL)
 493                 {
 494                         /*
 495                          * Multiple result relations (due to inheritance)
 496                          * parseTree->resultRelations identifies them all
 497                          */
 498                         ResultRelInfo *resultRelInfo;
 499                         ListCell   *l;
 500
 501                         numResultRelations = list_length(resultRelations);
 502                         resultRelInfos = (ResultRelInfo *)
 503                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 504                         resultRelInfo = resultRelInfos;
 505                         foreach(l, resultRelations)
 506                         {
 507                                 initResultRelInfo(resultRelInfo,
 508                                                                   lfirst_int(l),
 509                                                                   rangeTable,
 510                                                                   operation,
 511                                                                   estate->es_instrument);
 512                                 resultRelInfo++;
 513                         }
 514                 }
 515                 else
 516                 {
 517                         /*
 518                          * Single result relation identified by
 519                          * parseTree->resultRelation
 520                          */
 521                         numResultRelations = 1;
 522                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 523                         initResultRelInfo(resultRelInfos,
 524                                                           parseTree->resultRelation,
 525                                                           rangeTable,
 526                                                           operation,
 527                                                           estate->es_instrument);
 528                 }
 529
 530                 estate->es_result_relations = resultRelInfos;
 531                 estate->es_num_result_relations = numResultRelations;
 532                 /* Initialize to first or only result rel */
 533                 estate->es_result_relation_info = resultRelInfos;
 534         }
 535         else
 536         {
 537                 /*
 538                  * if no result relation, then set state appropriately
 539                  */
 540                 estate->es_result_relations = NULL;
 541                 estate->es_num_result_relations = 0;
 542                 estate->es_result_relation_info = NULL;
 543         }
 544
 545         /*
 546          * Detect whether we're doing SELECT INTO.  If so, set the es_into_oids
 547          * flag appropriately so that the plan tree will be initialized with
 548          * the correct tuple descriptors.
 549          */
 550         do_select_into = false;
 551
 552         if (operation == CMD_SELECT && parseTree->into != NULL)
 553         {
 554                 do_select_into = true;
 555                 estate->es_select_into = true;
 556                 estate->es_into_oids = parseTree->intoHasOids;
 557         }
 558
 559         /*
 560          * Have to lock relations selected FOR UPDATE/FOR SHARE
 561          */
 562         estate->es_rowMarks = NIL;
 563         estate->es_forUpdate = parseTree->forUpdate;
 564         estate->es_rowNoWait = parseTree->rowNoWait;
 565         if (parseTree->rowMarks != NIL)
 566         {
 567                 ListCell   *l;
 568
 569                 foreach(l, parseTree->rowMarks)
 570                 {
 571                         Index           rti = lfirst_int(l);
 572                         Oid                     relid = getrelid(rti, rangeTable);
 573                         Relation        relation;
 574                         execRowMark *erm;
 575
 576                         relation = heap_open(relid, RowShareLock);
 577                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 578                         erm->relation = relation;
 579                         erm->rti = rti;
 580                         snprintf(erm->resname, sizeof(erm->resname), "ctid%u", rti);
 581                         estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
 582                 }
 583         }
 584
 585         /*
 586          * initialize the executor "tuple" table.  We need slots for all the
 587          * plan nodes, plus possibly output slots for the junkfilter(s). At
 588          * this point we aren't sure if we need junkfilters, so just add slots
 589          * for them unconditionally.
 590          */
 591         {
 592                 int                     nSlots = ExecCountSlotsNode(plan);
 593
 594                 if (parseTree->resultRelations != NIL)
 595                         nSlots += list_length(parseTree->resultRelations);
 596                 else
 597                         nSlots += 1;
 598                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 599         }
 600
 601         /* mark EvalPlanQual not active */
 602         estate->es_topPlan = plan;
 603         estate->es_evalPlanQual = NULL;
 604         estate->es_evTupleNull = NULL;
 605         estate->es_evTuple = NULL;
 606         estate->es_useEvalPlan = false;
 607
 608         /*
 609          * initialize the private state information for all the nodes in the
 610          * query tree.  This opens files, allocates storage and leaves us
 611          * ready to start processing tuples.
 612          */
 613         planstate = ExecInitNode(plan, estate);
 614
 615         /*
 616          * Get the tuple descriptor describing the type of tuples to return.
 617          * (this is especially important if we are creating a relation with
 618          * "SELECT INTO")
 619          */
 620         tupType = ExecGetResultType(planstate);
 621
 622         /*
 623          * Initialize the junk filter if needed.  SELECT and INSERT queries
 624          * need a filter if there are any junk attrs in the tlist.      INSERT and
 625          * SELECT INTO also need a filter if the plan may return raw disk
 626          * tuples (else heap_insert will be scribbling on the source
 627          * relation!). UPDATE and DELETE always need a filter, since there's
 628          * always a junk 'ctid' attribute present --- no need to look first.
 629          */
 630         {
 631                 bool            junk_filter_needed = false;
 632                 ListCell   *tlist;
 633
 634                 switch (operation)
 635                 {
 636                         case CMD_SELECT:
 637                         case CMD_INSERT:
 638                                 foreach(tlist, plan->targetlist)
 639                                 {
 640                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 641
 642                                         if (tle->resjunk)
 643                                         {
 644                                                 junk_filter_needed = true;
 645                                                 break;
 646                                         }
 647                                 }
 648                                 if (!junk_filter_needed &&
 649                                         (operation == CMD_INSERT || do_select_into) &&
 650                                         ExecMayReturnRawTuples(planstate))
 651                                         junk_filter_needed = true;
 652                                 break;
 653                         case CMD_UPDATE:
 654                         case CMD_DELETE:
 655                                 junk_filter_needed = true;
 656                                 break;
 657                         default:
 658                                 break;
 659                 }
 660
 661                 if (junk_filter_needed)
 662                 {
 663                         /*
 664                          * If there are multiple result relations, each one needs its
 665                          * own junk filter.  Note this is only possible for
 666                          * UPDATE/DELETE, so we can't be fooled by some needing a
 667                          * filter and some not.
 668                          */
 669                         if (parseTree->resultRelations != NIL)
 670                         {
 671                                 PlanState **appendplans;
 672                                 int                     as_nplans;
 673                                 ResultRelInfo *resultRelInfo;
 674                                 int                     i;
 675
 676                                 /* Top plan had better be an Append here. */
 677                                 Assert(IsA(plan, Append));
 678                                 Assert(((Append *) plan)->isTarget);
 679                                 Assert(IsA(planstate, AppendState));
 680                                 appendplans = ((AppendState *) planstate)->appendplans;
 681                                 as_nplans = ((AppendState *) planstate)->as_nplans;
 682                                 Assert(as_nplans == estate->es_num_result_relations);
 683                                 resultRelInfo = estate->es_result_relations;
 684                                 for (i = 0; i < as_nplans; i++)
 685                                 {
 686                                         PlanState  *subplan = appendplans[i];
 687                                         JunkFilter *j;
 688
 689                                         j = ExecInitJunkFilter(subplan->plan->targetlist,
 690                                                                                    resultRelInfo->ri_RelationDesc->rd_att->tdhasoid,
 691                                                                                    ExecAllocTableSlot(estate->es_tupleTable));
 692                                         resultRelInfo->ri_junkFilter = j;
 693                                         resultRelInfo++;
 694                                 }
 695
 696                                 /*
 697                                  * Set active junkfilter too; at this point ExecInitAppend
 698                                  * has already selected an active result relation...
 699                                  */
 700                                 estate->es_junkFilter =
 701                                         estate->es_result_relation_info->ri_junkFilter;
 702                         }
 703                         else
 704                         {
 705                                 /* Normal case with just one JunkFilter */
 706                                 JunkFilter *j;
 707
 708                                 j = ExecInitJunkFilter(planstate->plan->targetlist,
 709                                                                            tupType->tdhasoid,
 710                                                           ExecAllocTableSlot(estate->es_tupleTable));
 711                                 estate->es_junkFilter = j;
 712                                 if (estate->es_result_relation_info)
 713                                         estate->es_result_relation_info->ri_junkFilter = j;
 714
 715                                 /* For SELECT, want to return the cleaned tuple type */
 716                                 if (operation == CMD_SELECT)
 717                                         tupType = j->jf_cleanTupType;
 718                         }
 719                 }
 720                 else
 721                         estate->es_junkFilter = NULL;
 722         }
 723
 724         /*
 725          * If doing SELECT INTO, initialize the "into" relation.  We must wait
 726          * till now so we have the "clean" result tuple type to create the new
 727          * table from.
 728          *
 729          * If EXPLAIN, skip creating the "into" relation.
 730          */
 731         intoRelationDesc = NULL;
 732
 733         if (do_select_into && !explainOnly)
 734         {
 735                 char       *intoName;
 736                 Oid                     namespaceId;
 737                 AclResult       aclresult;
 738                 Oid                     intoRelationId;
 739                 TupleDesc       tupdesc;
 740
 741                 /*
 742                  * find namespace to create in, check permissions
 743                  */
 744                 intoName = parseTree->into->relname;
 745                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 746
 747                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 748                                                                                   ACL_CREATE);
 749                 if (aclresult != ACLCHECK_OK)
 750                         aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
 751                                                    get_namespace_name(namespaceId));
 752
 753                 /*
 754                  * have to copy tupType to get rid of constraints
 755                  */
 756                 tupdesc = CreateTupleDescCopy(tupType);
 757
 758                 intoRelationId = heap_create_with_catalog(intoName,
 759                                                                                                   namespaceId,
 760                                                                                                   InvalidOid,
 761                                                                                                   InvalidOid,
 762                                                                                                   tupdesc,
 763                                                                                                   RELKIND_RELATION,
 764                                                                                                   false,
 765                                                                                                   true,
 766                                                                                                   0,
 767                                                                                                   ONCOMMIT_NOOP,
 768                                                                                                   allowSystemTableMods);
 769
 770                 FreeTupleDesc(tupdesc);
 771
 772                 /*
 773                  * Advance command counter so that the newly-created relation's
 774                  * catalog tuples will be visible to heap_open.
 775                  */
 776                 CommandCounterIncrement();
 777
 778                 /*
 779                  * If necessary, create a TOAST table for the into relation. Note
 780                  * that AlterTableCreateToastTable ends with
 781                  * CommandCounterIncrement(), so that the TOAST table will be
 782                  * visible for insertion.
 783                  */
 784                 AlterTableCreateToastTable(intoRelationId, true);
 785
 786                 /*
 787                  * And open the constructed table for writing.
 788                  */
 789                 intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock);
 790
 791                 /* use_wal off requires rd_targblock be initially invalid */
 792                 Assert(intoRelationDesc->rd_targblock == InvalidBlockNumber);
 793
 794                 /*
 795                  * We can skip WAL-logging the insertions, unless PITR is in use.
 796                  *
 797                  * Note that for a non-temp INTO table, this is safe only because
 798                  * we know that the catalog changes above will have been WAL-logged,
 799                  * and so RecordTransactionCommit will think it needs to WAL-log the
 800                  * eventual transaction commit.  Else the commit might be lost, even
 801                  * though all the data is safely fsync'd ...
 802                  */
 803                 estate->es_into_relation_use_wal = XLogArchivingActive();
 804         }
 805
 806         estate->es_into_relation_descriptor = intoRelationDesc;
 807
 808         queryDesc->tupDesc = tupType;
 809         queryDesc->planstate = planstate;
 810 }
 811
 812 /*
 813  * Initialize ResultRelInfo data for one result relation
 814  */
 815 static void
 816 initResultRelInfo(ResultRelInfo *resultRelInfo,
 817                                   Index resultRelationIndex,
 818                                   List *rangeTable,
 819                                   CmdType operation,
 820                                   bool doInstrument)
 821 {
 822         Oid                     resultRelationOid;
 823         Relation        resultRelationDesc;
 824
 825         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 826         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 827
 828         switch (resultRelationDesc->rd_rel->relkind)
 829         {
 830                 case RELKIND_SEQUENCE:
 831                         ereport(ERROR,
 832                                         (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 833                                          errmsg("cannot change sequence \"%s\"",
 834                                                   RelationGetRelationName(resultRelationDesc))));
 835                         break;
 836                 case RELKIND_TOASTVALUE:
 837                         ereport(ERROR,
 838                                         (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 839                                          errmsg("cannot change TOAST relation \"%s\"",
 840                                                   RelationGetRelationName(resultRelationDesc))));
 841                         break;
 842                 case RELKIND_VIEW:
 843                         ereport(ERROR,
 844                                         (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 845                                          errmsg("cannot change view \"%s\"",
 846                                                   RelationGetRelationName(resultRelationDesc))));
 847                         break;
 848         }
 849
 850         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 851         resultRelInfo->type = T_ResultRelInfo;
 852         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 853         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 854         resultRelInfo->ri_NumIndices = 0;
 855         resultRelInfo->ri_IndexRelationDescs = NULL;
 856         resultRelInfo->ri_IndexRelationInfo = NULL;
 857         /* make a copy so as not to depend on relcache info not changing... */
 858         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 859         if (resultRelInfo->ri_TrigDesc)
 860         {
 861                 int             n = resultRelInfo->ri_TrigDesc->numtriggers;
 862
 863                 resultRelInfo->ri_TrigFunctions = (FmgrInfo *)
 864                         palloc0(n * sizeof(FmgrInfo));
 865                 if (doInstrument)
 866                         resultRelInfo->ri_TrigInstrument = InstrAlloc(n);
 867                 else
 868                         resultRelInfo->ri_TrigInstrument = NULL;
 869         }
 870         else
 871         {
 872                 resultRelInfo->ri_TrigFunctions = NULL;
 873                 resultRelInfo->ri_TrigInstrument = NULL;
 874         }
 875         resultRelInfo->ri_ConstraintExprs = NULL;
 876         resultRelInfo->ri_junkFilter = NULL;
 877
 878         /*
 879          * If there are indices on the result relation, open them and save
 880          * descriptors in the result relation info, so that we can add new
 881          * index entries for the tuples we add/update.  We need not do this
 882          * for a DELETE, however, since deletion doesn't affect indexes.
 883          */
 884         if (resultRelationDesc->rd_rel->relhasindex &&
 885                 operation != CMD_DELETE)
 886                 ExecOpenIndices(resultRelInfo);
 887 }
 888
 889 /*
 890  *              ExecContextForcesOids
 891  *
 892  * This is pretty grotty: when doing INSERT, UPDATE, or SELECT INTO,
 893  * we need to ensure that result tuples have space for an OID iff they are
 894  * going to be stored into a relation that has OIDs.  In other contexts
 895  * we are free to choose whether to leave space for OIDs in result tuples
 896  * (we generally don't want to, but we do if a physical-tlist optimization
 897  * is possible).  This routine checks the plan context and returns TRUE if the
 898  * choice is forced, FALSE if the choice is not forced.  In the TRUE case,
 899  * *hasoids is set to the required value.
 900  *
 901  * One reason this is ugly is that all plan nodes in the plan tree will emit
 902  * tuples with space for an OID, though we really only need the topmost node
 903  * to do so.  However, node types like Sort don't project new tuples but just
 904  * return their inputs, and in those cases the requirement propagates down
 905  * to the input node.  Eventually we might make this code smart enough to
 906  * recognize how far down the requirement really goes, but for now we just
 907  * make all plan nodes do the same thing if the top level forces the choice.
 908  *
 909  * We assume that estate->es_result_relation_info is already set up to
 910  * describe the target relation.  Note that in an UPDATE that spans an
 911  * inheritance tree, some of the target relations may have OIDs and some not.
 912  * We have to make the decisions on a per-relation basis as we initialize
 913  * each of the child plans of the topmost Append plan.
 914  *
 915  * SELECT INTO is even uglier, because we don't have the INTO relation's
 916  * descriptor available when this code runs; we have to look aside at a
 917  * flag set by InitPlan().
 918  */
 919 bool
 920 ExecContextForcesOids(PlanState *planstate, bool *hasoids)
 921 {
 922         if (planstate->state->es_select_into)
 923         {
 924                 *hasoids = planstate->state->es_into_oids;
 925                 return true;
 926         }
 927         else
 928         {
 929                 ResultRelInfo *ri = planstate->state->es_result_relation_info;
 930
 931                 if (ri != NULL)
 932                 {
 933                         Relation        rel = ri->ri_RelationDesc;
 934
 935                         if (rel != NULL)
 936                         {
 937                                 *hasoids = rel->rd_rel->relhasoids;
 938                                 return true;
 939                         }
 940                 }
 941         }
 942
 943         return false;
 944 }
 945
 946 /* ----------------------------------------------------------------
 947  *              ExecEndPlan
 948  *
 949  *              Cleans up the query plan -- closes files and frees up storage
 950  *
 951  * NOTE: we are no longer very worried about freeing storage per se
 952  * in this code; FreeExecutorState should be guaranteed to release all
 953  * memory that needs to be released.  What we are worried about doing
 954  * is closing relations and dropping buffer pins.  Thus, for example,
 955  * tuple tables must be cleared or dropped to ensure pins are released.
 956  * ----------------------------------------------------------------
 957  */
 958 void
 959 ExecEndPlan(PlanState *planstate, EState *estate)
 960 {
 961         ResultRelInfo *resultRelInfo;
 962         int                     i;
 963         ListCell   *l;
 964
 965         /*
 966          * shut down any PlanQual processing we were doing
 967          */
 968         if (estate->es_evalPlanQual != NULL)
 969                 EndEvalPlanQual(estate);
 970
 971         /*
 972          * shut down the node-type-specific query processing
 973          */
 974         ExecEndNode(planstate);
 975
 976         /*
 977          * destroy the executor "tuple" table.
 978          */
 979         ExecDropTupleTable(estate->es_tupleTable, true);
 980         estate->es_tupleTable = NULL;
 981
 982         /*
 983          * close the result relation(s) if any, but hold locks until xact
 984          * commit.
 985          */
 986         resultRelInfo = estate->es_result_relations;
 987         for (i = estate->es_num_result_relations; i > 0; i--)
 988         {
 989                 /* Close indices and then the relation itself */
 990                 ExecCloseIndices(resultRelInfo);
 991                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 992                 resultRelInfo++;
 993         }
 994
 995         /*
 996          * close the "into" relation if necessary, again keeping lock
 997          */
 998         if (estate->es_into_relation_descriptor != NULL)
 999         {
1000                 /*
1001                  * If we skipped using WAL, and it's not a temp relation,
1002                  * we must force the relation down to disk before it's
1003                  * safe to commit the transaction.  This requires forcing
1004                  * out any dirty buffers and then doing a forced fsync.
1005                  */
1006                 if (!estate->es_into_relation_use_wal &&
1007                         !estate->es_into_relation_descriptor->rd_istemp)
1008                 {
1009                         FlushRelationBuffers(estate->es_into_relation_descriptor);
1010                         smgrimmedsync(estate->es_into_relation_descriptor->rd_smgr);
1011                 }
1012
1013                 heap_close(estate->es_into_relation_descriptor, NoLock);
1014         }
1015
1016         /*
1017          * close any relations selected FOR UPDATE/FOR SHARE, again keeping locks
1018          */
1019         foreach(l, estate->es_rowMarks)
1020         {
1021                 execRowMark *erm = lfirst(l);
1022
1023                 heap_close(erm->relation, NoLock);
1024         }
1025 }
1026
1027 /* ----------------------------------------------------------------
1028  *              ExecutePlan
1029  *
1030  *              processes the query plan to retrieve 'numberTuples' tuples in the
1031  *              direction specified.
1032  *
1033  *              Retrieves all tuples if numberTuples is 0
1034  *
1035  *              result is either a slot containing the last tuple in the case
1036  *              of a SELECT or NULL otherwise.
1037  *
1038  * Note: the ctid attribute is a 'junk' attribute that is removed before the
1039  * user can see it
1040  * ----------------------------------------------------------------
1041  */
1042 static TupleTableSlot *
1043 ExecutePlan(EState *estate,
1044                         PlanState *planstate,
1045                         CmdType operation,
1046                         long numberTuples,
1047                         ScanDirection direction,
1048                         DestReceiver *dest)
1049 {
1050         JunkFilter *junkfilter;
1051         TupleTableSlot *slot;
1052         ItemPointer tupleid = NULL;
1053         ItemPointerData tuple_ctid;
1054         long            current_tuple_count;
1055         TupleTableSlot *result;
1056
1057         /*
1058          * initialize local variables
1059          */
1060         slot = NULL;
1061         current_tuple_count = 0;
1062         result = NULL;
1063
1064         /*
1065          * Set the direction.
1066          */
1067         estate->es_direction = direction;
1068
1069         /*
1070          * Process BEFORE EACH STATEMENT triggers
1071          */
1072         switch (operation)
1073         {
1074                 case CMD_UPDATE:
1075                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
1076                         break;
1077                 case CMD_DELETE:
1078                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
1079                         break;
1080                 case CMD_INSERT:
1081                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
1082                         break;
1083                 default:
1084                         /* do nothing */
1085                         break;
1086         }
1087
1088         /*
1089          * Loop until we've processed the proper number of tuples from the
1090          * plan.
1091          */
1092
1093         for (;;)
1094         {
1095                 /* Reset the per-output-tuple exprcontext */
1096                 ResetPerTupleExprContext(estate);
1097
1098                 /*
1099                  * Execute the plan and obtain a tuple
1100                  */
1101 lnext:  ;
1102                 if (estate->es_useEvalPlan)
1103                 {
1104                         slot = EvalPlanQualNext(estate);
1105                         if (TupIsNull(slot))
1106                                 slot = ExecProcNode(planstate);
1107                 }
1108                 else
1109                         slot = ExecProcNode(planstate);
1110
1111                 /*
1112                  * if the tuple is null, then we assume there is nothing more to
1113                  * process so we just return null...
1114                  */
1115                 if (TupIsNull(slot))
1116                 {
1117                         result = NULL;
1118                         break;
1119                 }
1120
1121                 /*
1122                  * if we have a junk filter, then project a new tuple with the
1123                  * junk removed.
1124                  *
1125                  * Store this new "clean" tuple in the junkfilter's resultSlot.
1126                  * (Formerly, we stored it back over the "dirty" tuple, which is
1127                  * WRONG because that tuple slot has the wrong descriptor.)
1128                  *
1129                  * Also, extract all the junk information we need.
1130                  */
1131                 if ((junkfilter = estate->es_junkFilter) != NULL)
1132                 {
1133                         Datum           datum;
1134                         bool            isNull;
1135
1136                         /*
1137                          * extract the 'ctid' junk attribute.
1138                          */
1139                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1140                         {
1141                                 if (!ExecGetJunkAttribute(junkfilter,
1142                                                                                   slot,
1143                                                                                   "ctid",
1144                                                                                   &datum,
1145                                                                                   &isNull))
1146                                         elog(ERROR, "could not find junk ctid column");
1147
1148                                 /* shouldn't ever get a null result... */
1149                                 if (isNull)
1150                                         elog(ERROR, "ctid is NULL");
1151
1152                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1153                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1154                                                                                  * ctid!! */
1155                                 tupleid = &tuple_ctid;
1156                         }
1157                         /*
1158                          * Process any FOR UPDATE or FOR SHARE locking requested.
1159                          */
1160                         else if (estate->es_rowMarks != NIL)
1161                         {
1162                                 ListCell   *l;
1163
1164                 lmark:  ;
1165                                 foreach(l, estate->es_rowMarks)
1166                                 {
1167                                         execRowMark *erm = lfirst(l);
1168                                         Buffer          buffer;
1169                                         HeapTupleData tuple;
1170                                         TupleTableSlot *newSlot;
1171                                         LockTupleMode   lockmode;
1172                                         HTSU_Result             test;
1173
1174                                         if (!ExecGetJunkAttribute(junkfilter,
1175                                                                                           slot,
1176                                                                                           erm->resname,
1177                                                                                           &datum,
1178                                                                                           &isNull))
1179                                                 elog(ERROR, "could not find junk \"%s\" column",
1180                                                          erm->resname);
1181
1182                                         /* shouldn't ever get a null result... */
1183                                         if (isNull)
1184                                                 elog(ERROR, "\"%s\" is NULL", erm->resname);
1185
1186                                         if (estate->es_forUpdate)
1187                                                 lockmode = LockTupleExclusive;
1188                                         else
1189                                                 lockmode = LockTupleShared;
1190
1191                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1192                                         test = heap_lock_tuple(erm->relation, &tuple, &buffer,
1193                                                                                   estate->es_snapshot->curcid,
1194                                                                                   lockmode, estate->es_rowNoWait);
1195                                         ReleaseBuffer(buffer);
1196                                         switch (test)
1197                                         {
1198                                                 case HeapTupleSelfUpdated:
1199                                                         /* treat it as deleted; do not process */
1200                                                         goto lnext;
1201
1202                                                 case HeapTupleMayBeUpdated:
1203                                                         break;
1204
1205                                                 case HeapTupleUpdated:
1206                                                         if (IsXactIsoLevelSerializable)
1207                                                                 ereport(ERROR,
1208                                                                                 (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
1209                                                                                  errmsg("could not serialize access due to concurrent update")));
1210                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1211                                                                   (ItemPointer) DatumGetPointer(datum))))
1212                                                         {
1213                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1214                                                                 if (!(TupIsNull(newSlot)))
1215                                                                 {
1216                                                                         slot = newSlot;
1217                                                                         estate->es_useEvalPlan = true;
1218                                                                         goto lmark;
1219                                                                 }
1220                                                         }
1221
1222                                                         /*
1223                                                          * if tuple was deleted or PlanQual failed for
1224                                                          * updated tuple - we must not return this
1225                                                          * tuple!
1226                                                          */
1227                                                         goto lnext;
1228
1229                                                 default:
1230                                                         elog(ERROR, "unrecognized heap_lock_tuple status: %u",
1231                                                                  test);
1232                                                         return (NULL);
1233                                         }
1234                                 }
1235                         }
1236
1237                         /*
1238                          * Finally create a new "clean" tuple with all junk attributes
1239                          * removed
1240                          */
1241                         slot = ExecFilterJunk(junkfilter, slot);
1242                 }
1243
1244                 /*
1245                  * now that we have a tuple, do the appropriate thing with it..
1246                  * either return it to the user, add it to a relation someplace,
1247                  * delete it from a relation, or modify some of its attributes.
1248                  */
1249                 switch (operation)
1250                 {
1251                         case CMD_SELECT:
1252                                 ExecSelect(slot,        /* slot containing tuple */
1253                                                    dest,        /* destination's tuple-receiver obj */
1254                                                    estate);
1255                                 result = slot;
1256                                 break;
1257
1258                         case CMD_INSERT:
1259                                 ExecInsert(slot, tupleid, estate);
1260                                 result = NULL;
1261                                 break;
1262
1263                         case CMD_DELETE:
1264                                 ExecDelete(slot, tupleid, estate);
1265                                 result = NULL;
1266                                 break;
1267
1268                         case CMD_UPDATE:
1269                                 ExecUpdate(slot, tupleid, estate);
1270                                 result = NULL;
1271                                 break;
1272
1273                         default:
1274                                 elog(ERROR, "unrecognized operation code: %d",
1275                                          (int) operation);
1276                                 result = NULL;
1277                                 break;
1278                 }
1279
1280                 /*
1281                  * check our tuple count.. if we've processed the proper number
1282                  * then quit, else loop again and process more tuples.  Zero
1283                  * numberTuples means no limit.
1284                  */
1285                 current_tuple_count++;
1286                 if (numberTuples && numberTuples == current_tuple_count)
1287                         break;
1288         }
1289
1290         /*
1291          * Process AFTER EACH STATEMENT triggers
1292          */
1293         switch (operation)
1294         {
1295                 case CMD_UPDATE:
1296                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1297                         break;
1298                 case CMD_DELETE:
1299                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1300                         break;
1301                 case CMD_INSERT:
1302                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1303                         break;
1304                 default:
1305                         /* do nothing */
1306                         break;
1307         }
1308
1309         /*
1310          * here, result is either a slot containing a tuple in the case of a
1311          * SELECT or NULL otherwise.
1312          */
1313         return result;
1314 }
1315
1316 /* ----------------------------------------------------------------
1317  *              ExecSelect
1318  *
1319  *              SELECTs are easy.. we just pass the tuple to the appropriate
1320  *              print function.  The only complexity is when we do a
1321  *              "SELECT INTO", in which case we insert the tuple into
1322  *              the appropriate relation (note: this is a newly created relation
1323  *              so we don't need to worry about indices or locks.)
1324  * ----------------------------------------------------------------
1325  */
1326 static void
1327 ExecSelect(TupleTableSlot *slot,
1328                    DestReceiver *dest,
1329                    EState *estate)
1330 {
1331         /*
1332          * insert the tuple into the "into relation"
1333          *
1334          * XXX this probably ought to be replaced by a separate destination
1335          */
1336         if (estate->es_into_relation_descriptor != NULL)
1337         {
1338                 HeapTuple       tuple;
1339
1340                 tuple = ExecCopySlotTuple(slot);
1341                 heap_insert(estate->es_into_relation_descriptor, tuple,
1342                                         estate->es_snapshot->curcid,
1343                                         estate->es_into_relation_use_wal,
1344                                         false);         /* never any point in using FSM */
1345                 /* we know there are no indexes to update */
1346                 heap_freetuple(tuple);
1347                 IncrAppended();
1348         }
1349
1350         /*
1351          * send the tuple to the destination
1352          */
1353         (*dest->receiveSlot) (slot, dest);
1354         IncrRetrieved();
1355         (estate->es_processed)++;
1356 }
1357
1358 /* ----------------------------------------------------------------
1359  *              ExecInsert
1360  *
1361  *              INSERTs are trickier.. we have to insert the tuple into
1362  *              the base relation and insert appropriate tuples into the
1363  *              index relations.
1364  * ----------------------------------------------------------------
1365  */
1366 static void
1367 ExecInsert(TupleTableSlot *slot,
1368                    ItemPointer tupleid,
1369                    EState *estate)
1370 {
1371         HeapTuple       tuple;
1372         ResultRelInfo *resultRelInfo;
1373         Relation        resultRelationDesc;
1374         int                     numIndices;
1375         Oid                     newId;
1376
1377         /*
1378          * get the heap tuple out of the tuple table slot, making sure
1379          * we have a writable copy
1380          */
1381         tuple = ExecMaterializeSlot(slot);
1382
1383         /*
1384          * get information on the (current) result relation
1385          */
1386         resultRelInfo = estate->es_result_relation_info;
1387         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1388
1389         /* BEFORE ROW INSERT Triggers */
1390         if (resultRelInfo->ri_TrigDesc &&
1391           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1392         {
1393                 HeapTuple       newtuple;
1394
1395                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1396
1397                 if (newtuple == NULL)   /* "do nothing" */
1398                         return;
1399
1400                 if (newtuple != tuple)  /* modified by Trigger(s) */
1401                 {
1402                         /*
1403                          * Insert modified tuple into tuple table slot, replacing the
1404                          * original.  We assume that it was allocated in per-tuple
1405                          * memory context, and therefore will go away by itself. The
1406                          * tuple table slot should not try to clear it.
1407                          */
1408                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1409                         tuple = newtuple;
1410                 }
1411         }
1412
1413         /*
1414          * Check the constraints of the tuple
1415          */
1416         if (resultRelationDesc->rd_att->constr)
1417                 ExecConstraints(resultRelInfo, slot, estate);
1418
1419         /*
1420          * insert the tuple
1421          */
1422         newId = heap_insert(resultRelationDesc, tuple,
1423                                                 estate->es_snapshot->curcid,
1424                                                 true, true);
1425
1426         IncrAppended();
1427         (estate->es_processed)++;
1428         estate->es_lastoid = newId;
1429         setLastTid(&(tuple->t_self));
1430
1431         /*
1432          * process indices
1433          *
1434          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1435          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1436          * field.
1437          */
1438         numIndices = resultRelInfo->ri_NumIndices;
1439         if (numIndices > 0)
1440                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1441
1442         /* AFTER ROW INSERT Triggers */
1443         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1444 }
1445
1446 /* ----------------------------------------------------------------
1447  *              ExecDelete
1448  *
1449  *              DELETE is like UPDATE, we delete the tuple and its
1450  *              index tuples.
1451  * ----------------------------------------------------------------
1452  */
1453 static void
1454 ExecDelete(TupleTableSlot *slot,
1455                    ItemPointer tupleid,
1456                    EState *estate)
1457 {
1458         ResultRelInfo *resultRelInfo;
1459         Relation        resultRelationDesc;
1460         ItemPointerData ctid;
1461         HTSU_Result     result;
1462
1463         /*
1464          * get information on the (current) result relation
1465          */
1466         resultRelInfo = estate->es_result_relation_info;
1467         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1468
1469         /* BEFORE ROW DELETE Triggers */
1470         if (resultRelInfo->ri_TrigDesc &&
1471           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1472         {
1473                 bool            dodelete;
1474
1475                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid,
1476                                                                                 estate->es_snapshot->curcid);
1477
1478                 if (!dodelete)                  /* "do nothing" */
1479                         return;
1480         }
1481
1482         /*
1483          * delete the tuple
1484          *
1485          * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that
1486          * the row to be deleted is visible to that snapshot, and throw a can't-
1487          * serialize error if not.  This is a special-case behavior needed for
1488          * referential integrity updates in serializable transactions.
1489          */
1490 ldelete:;
1491         result = heap_delete(resultRelationDesc, tupleid,
1492                                                  &ctid,
1493                                                  estate->es_snapshot->curcid,
1494                                                  estate->es_crosscheck_snapshot,
1495                                                  true /* wait for commit */ );
1496         switch (result)
1497         {
1498                 case HeapTupleSelfUpdated:
1499                         /* already deleted by self; nothing to do */
1500                         return;
1501
1502                 case HeapTupleMayBeUpdated:
1503                         break;
1504
1505                 case HeapTupleUpdated:
1506                         if (IsXactIsoLevelSerializable)
1507                                 ereport(ERROR,
1508                                                 (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
1509                                                  errmsg("could not serialize access due to concurrent update")));
1510                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1511                         {
1512                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1513                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1514
1515                                 if (!TupIsNull(epqslot))
1516                                 {
1517                                         *tupleid = ctid;
1518                                         goto ldelete;
1519                                 }
1520                         }
1521                         /* tuple already deleted; nothing to do */
1522                         return;
1523
1524                 default:
1525                         elog(ERROR, "unrecognized heap_delete status: %u", result);
1526                         return;
1527         }
1528
1529         IncrDeleted();
1530         (estate->es_processed)++;
1531
1532         /*
1533          * Note: Normally one would think that we have to delete index tuples
1534          * associated with the heap tuple now..
1535          *
1536          * ... but in POSTGRES, we have no need to do this because the vacuum
1537          * daemon automatically opens an index scan and deletes index tuples
1538          * when it finds deleted heap tuples. -cim 9/27/89
1539          */
1540
1541         /* AFTER ROW DELETE Triggers */
1542         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1543 }
1544
1545 /* ----------------------------------------------------------------
1546  *              ExecUpdate
1547  *
1548  *              note: we can't run UPDATE queries with transactions
1549  *              off because UPDATEs are actually INSERTs and our
1550  *              scan will mistakenly loop forever, updating the tuple
1551  *              it just inserted..      This should be fixed but until it
1552  *              is, we don't want to get stuck in an infinite loop
1553  *              which corrupts your database..
1554  * ----------------------------------------------------------------
1555  */
1556 static void
1557 ExecUpdate(TupleTableSlot *slot,
1558                    ItemPointer tupleid,
1559                    EState *estate)
1560 {
1561         HeapTuple       tuple;
1562         ResultRelInfo *resultRelInfo;
1563         Relation        resultRelationDesc;
1564         ItemPointerData ctid;
1565         HTSU_Result     result;
1566         int                     numIndices;
1567
1568         /*
1569          * abort the operation if not running transactions
1570          */
1571         if (IsBootstrapProcessingMode())
1572                 elog(ERROR, "cannot UPDATE during bootstrap");
1573
1574         /*
1575          * get the heap tuple out of the tuple table slot, making sure
1576          * we have a writable copy
1577          */
1578         tuple = ExecMaterializeSlot(slot);
1579
1580         /*
1581          * get information on the (current) result relation
1582          */
1583         resultRelInfo = estate->es_result_relation_info;
1584         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1585
1586         /* BEFORE ROW UPDATE Triggers */
1587         if (resultRelInfo->ri_TrigDesc &&
1588           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1589         {
1590                 HeapTuple       newtuple;
1591
1592                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1593                                                                                 tupleid, tuple,
1594                                                                                 estate->es_snapshot->curcid);
1595
1596                 if (newtuple == NULL)   /* "do nothing" */
1597                         return;
1598
1599                 if (newtuple != tuple)  /* modified by Trigger(s) */
1600                 {
1601                         /*
1602                          * Insert modified tuple into tuple table slot, replacing the
1603                          * original.  We assume that it was allocated in per-tuple
1604                          * memory context, and therefore will go away by itself. The
1605                          * tuple table slot should not try to clear it.
1606                          */
1607                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1608                         tuple = newtuple;
1609                 }
1610         }
1611
1612         /*
1613          * Check the constraints of the tuple
1614          *
1615          * If we generate a new candidate tuple after EvalPlanQual testing, we
1616          * must loop back here and recheck constraints.  (We don't need to
1617          * redo triggers, however.      If there are any BEFORE triggers then
1618          * trigger.c will have done heap_lock_tuple to lock the correct tuple,
1619          * so there's no need to do them again.)
1620          */
1621 lreplace:;
1622         if (resultRelationDesc->rd_att->constr)
1623                 ExecConstraints(resultRelInfo, slot, estate);
1624
1625         /*
1626          * replace the heap tuple
1627          *
1628          * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that
1629          * the row to be updated is visible to that snapshot, and throw a can't-
1630          * serialize error if not.  This is a special-case behavior needed for
1631          * referential integrity updates in serializable transactions.
1632          */
1633         result = heap_update(resultRelationDesc, tupleid, tuple,
1634                                                  &ctid,
1635                                                  estate->es_snapshot->curcid,
1636                                                  estate->es_crosscheck_snapshot,
1637                                                  true /* wait for commit */ );
1638         switch (result)
1639         {
1640                 case HeapTupleSelfUpdated:
1641                         /* already deleted by self; nothing to do */
1642                         return;
1643
1644                 case HeapTupleMayBeUpdated:
1645                         break;
1646
1647                 case HeapTupleUpdated:
1648                         if (IsXactIsoLevelSerializable)
1649                                 ereport(ERROR,
1650                                                 (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
1651                                                  errmsg("could not serialize access due to concurrent update")));
1652                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1653                         {
1654                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1655                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1656
1657                                 if (!TupIsNull(epqslot))
1658                                 {
1659                                         *tupleid = ctid;
1660                                         slot = ExecFilterJunk(estate->es_junkFilter, epqslot);
1661                                         tuple = ExecMaterializeSlot(slot);
1662                                         goto lreplace;
1663                                 }
1664                         }
1665                         /* tuple already deleted; nothing to do */
1666                         return;
1667
1668                 default:
1669                         elog(ERROR, "unrecognized heap_update status: %u", result);
1670                         return;
1671         }
1672
1673         IncrReplaced();
1674         (estate->es_processed)++;
1675
1676         /*
1677          * Note: instead of having to update the old index tuples associated
1678          * with the heap tuple, all we do is form and insert new index tuples.
1679          * This is because UPDATEs are actually DELETEs and INSERTs and index
1680          * tuple deletion is done automagically by the vacuum daemon. All we
1681          * do is insert new index tuples.  -cim 9/27/89
1682          */
1683
1684         /*
1685          * process indices
1686          *
1687          * heap_update updates a tuple in the base relation by invalidating it
1688          * and then inserting a new tuple to the relation.      As a side effect,
1689          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1690          * field.  So we now insert index tuples using the new tupleid stored
1691          * there.
1692          */
1693
1694         numIndices = resultRelInfo->ri_NumIndices;
1695         if (numIndices > 0)
1696                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1697
1698         /* AFTER ROW UPDATE Triggers */
1699         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1700 }
1701
1702 static const char *
1703 ExecRelCheck(ResultRelInfo *resultRelInfo,
1704                          TupleTableSlot *slot, EState *estate)
1705 {
1706         Relation        rel = resultRelInfo->ri_RelationDesc;
1707         int                     ncheck = rel->rd_att->constr->num_check;
1708         ConstrCheck *check = rel->rd_att->constr->check;
1709         ExprContext *econtext;
1710         MemoryContext oldContext;
1711         List       *qual;
1712         int                     i;
1713
1714         /*
1715          * If first time through for this result relation, build expression
1716          * nodetrees for rel's constraint expressions.  Keep them in the
1717          * per-query memory context so they'll survive throughout the query.
1718          */
1719         if (resultRelInfo->ri_ConstraintExprs == NULL)
1720         {
1721                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1722                 resultRelInfo->ri_ConstraintExprs =
1723                         (List **) palloc(ncheck * sizeof(List *));
1724                 for (i = 0; i < ncheck; i++)
1725                 {
1726                         /* ExecQual wants implicit-AND form */
1727                         qual = make_ands_implicit(stringToNode(check[i].ccbin));
1728                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1729                                 ExecPrepareExpr((Expr *) qual, estate);
1730                 }
1731                 MemoryContextSwitchTo(oldContext);
1732         }
1733
1734         /*
1735          * We will use the EState's per-tuple context for evaluating
1736          * constraint expressions (creating it if it's not already there).
1737          */
1738         econtext = GetPerTupleExprContext(estate);
1739
1740         /* Arrange for econtext's scan tuple to be the tuple under test */
1741         econtext->ecxt_scantuple = slot;
1742
1743         /* And evaluate the constraints */
1744         for (i = 0; i < ncheck; i++)
1745         {
1746                 qual = resultRelInfo->ri_ConstraintExprs[i];
1747
1748                 /*
1749                  * NOTE: SQL92 specifies that a NULL result from a constraint
1750                  * expression is not to be treated as a failure.  Therefore, tell
1751                  * ExecQual to return TRUE for NULL.
1752                  */
1753                 if (!ExecQual(qual, econtext, true))
1754                         return check[i].ccname;
1755         }
1756
1757         /* NULL result means no error */
1758         return NULL;
1759 }
1760
1761 void
1762 ExecConstraints(ResultRelInfo *resultRelInfo,
1763                                 TupleTableSlot *slot, EState *estate)
1764 {
1765         Relation        rel = resultRelInfo->ri_RelationDesc;
1766         TupleConstr *constr = rel->rd_att->constr;
1767
1768         Assert(constr);
1769
1770         if (constr->has_not_null)
1771         {
1772                 int                     natts = rel->rd_att->natts;
1773                 int                     attrChk;
1774
1775                 for (attrChk = 1; attrChk <= natts; attrChk++)
1776                 {
1777                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1778                                 slot_attisnull(slot, attrChk))
1779                                 ereport(ERROR,
1780                                                 (errcode(ERRCODE_NOT_NULL_VIOLATION),
1781                                                  errmsg("null value in column \"%s\" violates not-null constraint",
1782                                         NameStr(rel->rd_att->attrs[attrChk - 1]->attname))));
1783                 }
1784         }
1785
1786         if (constr->num_check > 0)
1787         {
1788                 const char *failed;
1789
1790                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1791                         ereport(ERROR,
1792                                         (errcode(ERRCODE_CHECK_VIOLATION),
1793                                          errmsg("new row for relation \"%s\" violates check constraint \"%s\"",
1794                                                         RelationGetRelationName(rel), failed)));
1795         }
1796 }
1797
1798 /*
1799  * Check a modified tuple to see if we want to process its updated version
1800  * under READ COMMITTED rules.
1801  *
1802  * See backend/executor/README for some info about how this works.
1803  */
1804 TupleTableSlot *
1805 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1806 {
1807         evalPlanQual *epq;
1808         EState     *epqstate;
1809         Relation        relation;
1810         HeapTupleData tuple;
1811         HeapTuple       copyTuple = NULL;
1812         bool            endNode;
1813
1814         Assert(rti != 0);
1815
1816         /*
1817          * find relation containing target tuple
1818          */
1819         if (estate->es_result_relation_info != NULL &&
1820                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1821                 relation = estate->es_result_relation_info->ri_RelationDesc;
1822         else
1823         {
1824                 ListCell   *l;
1825
1826                 relation = NULL;
1827                 foreach(l, estate->es_rowMarks)
1828                 {
1829                         if (((execRowMark *) lfirst(l))->rti == rti)
1830                         {
1831                                 relation = ((execRowMark *) lfirst(l))->relation;
1832                                 break;
1833                         }
1834                 }
1835                 if (relation == NULL)
1836                         elog(ERROR, "could not find RowMark for RT index %u", rti);
1837         }
1838
1839         /*
1840          * fetch tid tuple
1841          *
1842          * Loop here to deal with updated or busy tuples
1843          */
1844         tuple.t_self = *tid;
1845         for (;;)
1846         {
1847                 Buffer          buffer;
1848
1849                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1850                 {
1851                         TransactionId xwait = SnapshotDirty->xmax;
1852
1853                         /* xmin should not be dirty... */
1854                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1855                                 elog(ERROR, "t_xmin is uncommitted in tuple to be updated");
1856
1857                         /*
1858                          * If tuple is being updated by other transaction then we have
1859                          * to wait for its commit/abort.
1860                          */
1861                         if (TransactionIdIsValid(xwait))
1862                         {
1863                                 ReleaseBuffer(buffer);
1864                                 XactLockTableWait(xwait);
1865                                 continue;
1866                         }
1867
1868                         /*
1869                          * We got tuple - now copy it for use by recheck query.
1870                          */
1871                         copyTuple = heap_copytuple(&tuple);
1872                         ReleaseBuffer(buffer);
1873                         break;
1874                 }
1875
1876                 /*
1877                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1878                  * Note that it's possible to get invalid SnapshotDirty->tid if
1879                  * tuple updated by this transaction. Have we to check this ?
1880                  */
1881                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1882                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1883                 {
1884                         /* updated, so look at the updated copy */
1885                         tuple.t_self = SnapshotDirty->tid;
1886                         continue;
1887                 }
1888
1889                 /*
1890                  * Deleted or updated by this transaction; forget it.
1891                  */
1892                 return NULL;
1893         }
1894
1895         /*
1896          * For UPDATE/DELETE we have to return tid of actual row we're
1897          * executing PQ for.
1898          */
1899         *tid = tuple.t_self;
1900
1901         /*
1902          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1903          */
1904         epq = estate->es_evalPlanQual;
1905         endNode = true;
1906
1907         if (epq != NULL && epq->rti == 0)
1908         {
1909                 /* Top PQ stack entry is idle, so re-use it */
1910                 Assert(!(estate->es_useEvalPlan) && epq->next == NULL);
1911                 epq->rti = rti;
1912                 endNode = false;
1913         }
1914
1915         /*
1916          * If this is request for another RTE - Ra, - then we have to check
1917          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1918          * updated again and we have to re-start old execution for Ra and
1919          * forget all what we done after Ra was suspended. Cool? -:))
1920          */
1921         if (epq != NULL && epq->rti != rti &&
1922                 epq->estate->es_evTuple[rti - 1] != NULL)
1923         {
1924                 do
1925                 {
1926                         evalPlanQual *oldepq;
1927
1928                         /* stop execution */
1929                         EvalPlanQualStop(epq);
1930                         /* pop previous PlanQual from the stack */
1931                         oldepq = epq->next;
1932                         Assert(oldepq && oldepq->rti != 0);
1933                         /* push current PQ to freePQ stack */
1934                         oldepq->free = epq;
1935                         epq = oldepq;
1936                         estate->es_evalPlanQual = epq;
1937                 } while (epq->rti != rti);
1938         }
1939
1940         /*
1941          * If we are requested for another RTE then we have to suspend
1942          * execution of current PlanQual and start execution for new one.
1943          */
1944         if (epq == NULL || epq->rti != rti)
1945         {
1946                 /* try to reuse plan used previously */
1947                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1948
1949                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1950                 {
1951                         newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual));
1952                         newepq->free = NULL;
1953                         newepq->estate = NULL;
1954                         newepq->planstate = NULL;
1955                 }
1956                 else
1957                 {
1958                         /* recycle previously used PlanQual */
1959                         Assert(newepq->estate == NULL);
1960                         epq->free = NULL;
1961                 }
1962                 /* push current PQ to the stack */
1963                 newepq->next = epq;
1964                 epq = newepq;
1965                 estate->es_evalPlanQual = epq;
1966                 epq->rti = rti;
1967                 endNode = false;
1968         }
1969
1970         Assert(epq->rti == rti);
1971
1972         /*
1973          * Ok - we're requested for the same RTE.  Unfortunately we still have
1974          * to end and restart execution of the plan, because ExecReScan
1975          * wouldn't ensure that upper plan nodes would reset themselves.  We
1976          * could make that work if insertion of the target tuple were
1977          * integrated with the Param mechanism somehow, so that the upper plan
1978          * nodes know that their children's outputs have changed.
1979          *
1980          * Note that the stack of free evalPlanQual nodes is quite useless at the
1981          * moment, since it only saves us from pallocing/releasing the
1982          * evalPlanQual nodes themselves.  But it will be useful once we
1983          * implement ReScan instead of end/restart for re-using PlanQual
1984          * nodes.
1985          */
1986         if (endNode)
1987         {
1988                 /* stop execution */
1989                 EvalPlanQualStop(epq);
1990         }
1991
1992         /*
1993          * Initialize new recheck query.
1994          *
1995          * Note: if we were re-using PlanQual plans via ExecReScan, we'd need to
1996          * instead copy down changeable state from the top plan (including
1997          * es_result_relation_info, es_junkFilter) and reset locally
1998          * changeable state in the epq (including es_param_exec_vals,
1999          * es_evTupleNull).
2000          */
2001         EvalPlanQualStart(epq, estate, epq->next);
2002
2003         /*
2004          * free old RTE' tuple, if any, and store target tuple where
2005          * relation's scan node will see it
2006          */
2007         epqstate = epq->estate;
2008         if (epqstate->es_evTuple[rti - 1] != NULL)
2009                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
2010         epqstate->es_evTuple[rti - 1] = copyTuple;
2011
2012         return EvalPlanQualNext(estate);
2013 }
2014
2015 static TupleTableSlot *
2016 EvalPlanQualNext(EState *estate)
2017 {
2018         evalPlanQual *epq = estate->es_evalPlanQual;
2019         MemoryContext oldcontext;
2020         TupleTableSlot *slot;
2021
2022         Assert(epq->rti != 0);
2023
2024 lpqnext:;
2025         oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt);
2026         slot = ExecProcNode(epq->planstate);
2027         MemoryContextSwitchTo(oldcontext);
2028
2029         /*
2030          * No more tuples for this PQ. Continue previous one.
2031          */
2032         if (TupIsNull(slot))
2033         {
2034                 evalPlanQual *oldepq;
2035
2036                 /* stop execution */
2037                 EvalPlanQualStop(epq);
2038                 /* pop old PQ from the stack */
2039                 oldepq = epq->next;
2040                 if (oldepq == NULL)
2041                 {
2042                         /* this is the first (oldest) PQ - mark as free */
2043                         epq->rti = 0;
2044                         estate->es_useEvalPlan = false;
2045                         /* and continue Query execution */
2046                         return (NULL);
2047                 }
2048                 Assert(oldepq->rti != 0);
2049                 /* push current PQ to freePQ stack */
2050                 oldepq->free = epq;
2051                 epq = oldepq;
2052                 estate->es_evalPlanQual = epq;
2053                 goto lpqnext;
2054         }
2055
2056         return (slot);
2057 }
2058
2059 static void
2060 EndEvalPlanQual(EState *estate)
2061 {
2062         evalPlanQual *epq = estate->es_evalPlanQual;
2063
2064         if (epq->rti == 0)                      /* plans already shutdowned */
2065         {
2066                 Assert(epq->next == NULL);
2067                 return;
2068         }
2069
2070         for (;;)
2071         {
2072                 evalPlanQual *oldepq;
2073
2074                 /* stop execution */
2075                 EvalPlanQualStop(epq);
2076                 /* pop old PQ from the stack */
2077                 oldepq = epq->next;
2078                 if (oldepq == NULL)
2079                 {
2080                         /* this is the first (oldest) PQ - mark as free */
2081                         epq->rti = 0;
2082                         estate->es_useEvalPlan = false;
2083                         break;
2084                 }
2085                 Assert(oldepq->rti != 0);
2086                 /* push current PQ to freePQ stack */
2087                 oldepq->free = epq;
2088                 epq = oldepq;
2089                 estate->es_evalPlanQual = epq;
2090         }
2091 }
2092
2093 /*
2094  * Start execution of one level of PlanQual.
2095  *
2096  * This is a cut-down version of ExecutorStart(): we copy some state from
2097  * the top-level estate rather than initializing it fresh.
2098  */
2099 static void
2100 EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
2101 {
2102         EState     *epqstate;
2103         int                     rtsize;
2104         MemoryContext oldcontext;
2105
2106         rtsize = list_length(estate->es_range_table);
2107
2108         epq->estate = epqstate = CreateExecutorState();
2109
2110         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
2111
2112         /*
2113          * The epqstates share the top query's copy of unchanging state such
2114          * as the snapshot, rangetable, result-rel info, and external Param
2115          * info. They need their own copies of local state, including a tuple
2116          * table, es_param_exec_vals, etc.
2117          */
2118         epqstate->es_direction = ForwardScanDirection;
2119         epqstate->es_snapshot = estate->es_snapshot;
2120         epqstate->es_crosscheck_snapshot = estate->es_crosscheck_snapshot;
2121         epqstate->es_range_table = estate->es_range_table;
2122         epqstate->es_result_relations = estate->es_result_relations;
2123         epqstate->es_num_result_relations = estate->es_num_result_relations;
2124         epqstate->es_result_relation_info = estate->es_result_relation_info;
2125         epqstate->es_junkFilter = estate->es_junkFilter;
2126         epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor;
2127         epqstate->es_into_relation_use_wal = estate->es_into_relation_use_wal;
2128         epqstate->es_param_list_info = estate->es_param_list_info;
2129         if (estate->es_topPlan->nParamExec > 0)
2130                 epqstate->es_param_exec_vals = (ParamExecData *)
2131                         palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
2132         epqstate->es_rowMarks = estate->es_rowMarks;
2133         epqstate->es_forUpdate = estate->es_forUpdate;
2134         epqstate->es_rowNoWait = estate->es_rowNoWait;
2135         epqstate->es_instrument = estate->es_instrument;
2136         epqstate->es_select_into = estate->es_select_into;
2137         epqstate->es_into_oids = estate->es_into_oids;
2138         epqstate->es_topPlan = estate->es_topPlan;
2139
2140         /*
2141          * Each epqstate must have its own es_evTupleNull state, but all the
2142          * stack entries share es_evTuple state.  This allows sub-rechecks to
2143          * inherit the value being examined by an outer recheck.
2144          */
2145         epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool));
2146         if (priorepq == NULL)
2147                 /* first PQ stack entry */
2148                 epqstate->es_evTuple = (HeapTuple *)
2149                         palloc0(rtsize * sizeof(HeapTuple));
2150         else
2151                 /* later stack entries share the same storage */
2152                 epqstate->es_evTuple = priorepq->estate->es_evTuple;
2153
2154         epqstate->es_tupleTable =
2155                 ExecCreateTupleTable(estate->es_tupleTable->size);
2156
2157         epq->planstate = ExecInitNode(estate->es_topPlan, epqstate);
2158
2159         MemoryContextSwitchTo(oldcontext);
2160 }
2161
2162 /*
2163  * End execution of one level of PlanQual.
2164  *
2165  * This is a cut-down version of ExecutorEnd(); basically we want to do most
2166  * of the normal cleanup, but *not* close result relations (which we are
2167  * just sharing from the outer query).
2168  */
2169 static void
2170 EvalPlanQualStop(evalPlanQual *epq)
2171 {
2172         EState     *epqstate = epq->estate;
2173         MemoryContext oldcontext;
2174
2175         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
2176
2177         ExecEndNode(epq->planstate);
2178
2179         ExecDropTupleTable(epqstate->es_tupleTable, true);
2180         epqstate->es_tupleTable = NULL;
2181
2182         if (epqstate->es_evTuple[epq->rti - 1] != NULL)
2183         {
2184                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
2185                 epqstate->es_evTuple[epq->rti - 1] = NULL;
2186         }
2187
2188         MemoryContextSwitchTo(oldcontext);
2189
2190         FreeExecutorState(epqstate);
2191
2192         epq->estate = NULL;
2193         epq->planstate = NULL;
2194 }