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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 and the execution state is required
  16  *       as arguments
  17  *
  18  *      ExecutorStart() must be called at the beginning of any execution of any
  19  *      query plan and ExecutorEnd() should always be called at the end of
  20  *      execution of a plan.
  21  *
  22  *      ExecutorRun accepts 'feature' and 'count' arguments that specify whether
  23  *      the plan is to be executed forwards, backwards, and for how many tuples.
  24  *
  25  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  26  * Portions Copyright (c) 1994, Regents of the University of California
  27  *
  28  *
  29  * IDENTIFICATION
  30  *        $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.141 2001/05/27 09:59:29 petere Exp $
  31  *
  32  *-------------------------------------------------------------------------
  33  */
  34 #include "postgres.h"
  35
  36 #include "access/heapam.h"
  37 #include "catalog/heap.h"
  38 #include "commands/command.h"
  39 #include "commands/trigger.h"
  40 #include "executor/execdebug.h"
  41 #include "executor/execdefs.h"
  42 #include "miscadmin.h"
  43 #include "optimizer/var.h"
  44 #include "parser/parsetree.h"
  45 #include "utils/acl.h"
  46
  47
  48 /* decls for local routines only used within this module */
  49 static TupleDesc InitPlan(CmdType operation,
  50                  Query *parseTree,
  51                  Plan *plan,
  52                  EState *estate);
  53 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  54                                   Index resultRelationIndex,
  55                                   List *rangeTable,
  56                                   CmdType operation);
  57 static void EndPlan(Plan *plan, EState *estate);
  58 static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan,
  59                         CmdType operation,
  60                         long numberTuples,
  61                         ScanDirection direction,
  62                         DestReceiver *destfunc);
  63 static void ExecRetrieve(TupleTableSlot *slot,
  64                          DestReceiver *destfunc,
  65                          EState *estate);
  66 static void ExecAppend(TupleTableSlot *slot, ItemPointer tupleid,
  67                    EState *estate);
  68 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  69                    EState *estate);
  70 static void ExecReplace(TupleTableSlot *slot, ItemPointer tupleid,
  71                         EState *estate);
  72 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  73 static void EndEvalPlanQual(EState *estate);
  74 static void ExecCheckQueryPerms(CmdType operation, Query *parseTree,
  75                                         Plan *plan);
  76 static void ExecCheckPlanPerms(Plan *plan, List *rangeTable,
  77                                    CmdType operation);
  78 static void ExecCheckRTPerms(List *rangeTable, CmdType operation);
  79 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  80
  81 /* end of local decls */
  82
  83
  84 /* ----------------------------------------------------------------
  85  *              ExecutorStart
  86  *
  87  *              This routine must be called at the beginning of any execution of any
  88  *              query plan
  89  *
  90  *              returns a TupleDesc which describes the attributes of the tuples to
  91  *              be returned by the query.
  92  *
  93  * NB: the CurrentMemoryContext when this is called must be the context
  94  * to be used as the per-query context for the query plan.      ExecutorRun()
  95  * and ExecutorEnd() must be called in this same memory context.
  96  * ----------------------------------------------------------------
  97  */
  98 TupleDesc
  99 ExecutorStart(QueryDesc *queryDesc, EState *estate)
 100 {
 101         TupleDesc       result;
 102
 103         /* sanity checks */
 104         Assert(queryDesc != NULL);
 105
 106         if (queryDesc->plantree->nParamExec > 0)
 107         {
 108                 estate->es_param_exec_vals = (ParamExecData *)
 109                         palloc(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 110                 MemSet(estate->es_param_exec_vals, 0,
 111                            queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 112         }
 113
 114         /*
 115          * Make our own private copy of the current queries snapshot data
 116          */
 117         if (QuerySnapshot == NULL)
 118                 estate->es_snapshot = NULL;
 119         else
 120         {
 121                 estate->es_snapshot = (Snapshot) palloc(sizeof(SnapshotData));
 122                 memcpy(estate->es_snapshot, QuerySnapshot, sizeof(SnapshotData));
 123                 if (estate->es_snapshot->xcnt > 0)
 124                 {
 125                         estate->es_snapshot->xip = (TransactionId *)
 126                                 palloc(estate->es_snapshot->xcnt * sizeof(TransactionId));
 127                         memcpy(estate->es_snapshot->xip, QuerySnapshot->xip,
 128                                    estate->es_snapshot->xcnt * sizeof(TransactionId));
 129                 }
 130         }
 131
 132         /*
 133          * Initialize the plan
 134          */
 135         result = InitPlan(queryDesc->operation,
 136                                           queryDesc->parsetree,
 137                                           queryDesc->plantree,
 138                                           estate);
 139
 140         return result;
 141 }
 142
 143 /* ----------------------------------------------------------------
 144  *              ExecutorRun
 145  *
 146  *              This is the main routine of the executor module. It accepts
 147  *              the query descriptor from the traffic cop and executes the
 148  *              query plan.
 149  *
 150  *              ExecutorStart must have been called already.
 151  *
 152  *              the different features supported are:
 153  *                       EXEC_RUN:      retrieve all tuples in the forward direction
 154  *                       EXEC_FOR:      retrieve 'count' number of tuples in the forward dir
 155  *                       EXEC_BACK: retrieve 'count' number of tuples in the backward dir
 156  *                       EXEC_RETONE: return one tuple but don't 'retrieve' it
 157  *                                                 used in postquel function processing
 158  *
 159  *              Note: count = 0 is interpreted as "no limit".
 160  *
 161  * ----------------------------------------------------------------
 162  */
 163 TupleTableSlot *
 164 ExecutorRun(QueryDesc *queryDesc, EState *estate, int feature, long count)
 165 {
 166         CmdType         operation;
 167         Plan       *plan;
 168         TupleTableSlot *result;
 169         CommandDest dest;
 170         DestReceiver *destfunc;
 171
 172         /*
 173          * sanity checks
 174          */
 175         Assert(queryDesc != NULL);
 176
 177         /*
 178          * extract information from the query descriptor and the query
 179          * feature.
 180          */
 181         operation = queryDesc->operation;
 182         plan = queryDesc->plantree;
 183         dest = queryDesc->dest;
 184         destfunc = DestToFunction(dest);
 185         estate->es_processed = 0;
 186         estate->es_lastoid = InvalidOid;
 187
 188         /*
 189          * FIXME: the dest setup function ought to be handed the tuple desc
 190          * for the tuples to be output, but I'm not quite sure how to get that
 191          * info at this point.  For now, passing NULL is OK because no
 192          * existing dest setup function actually uses the pointer.
 193          */
 194         (*destfunc->setup) (destfunc, (TupleDesc) NULL);
 195
 196         switch (feature)
 197         {
 198                 case EXEC_RUN:
 199                         result = ExecutePlan(estate,
 200                                                                  plan,
 201                                                                  operation,
 202                                                                  count,
 203                                                                  ForwardScanDirection,
 204                                                                  destfunc);
 205                         break;
 206
 207                 case EXEC_FOR:
 208                         result = ExecutePlan(estate,
 209                                                                  plan,
 210                                                                  operation,
 211                                                                  count,
 212                                                                  ForwardScanDirection,
 213                                                                  destfunc);
 214                         break;
 215
 216                         /*
 217                          * retrieve next n "backward" tuples
 218                          */
 219                 case EXEC_BACK:
 220                         result = ExecutePlan(estate,
 221                                                                  plan,
 222                                                                  operation,
 223                                                                  count,
 224                                                                  BackwardScanDirection,
 225                                                                  destfunc);
 226                         break;
 227
 228                         /*
 229                          * return one tuple but don't "retrieve" it. (this is used by
 230                          * the rule manager..) -cim 9/14/89
 231                          */
 232                 case EXEC_RETONE:
 233                         result = ExecutePlan(estate,
 234                                                                  plan,
 235                                                                  operation,
 236                                                                  ONE_TUPLE,
 237                                                                  ForwardScanDirection,
 238                                                                  destfunc);
 239                         break;
 240
 241                 default:
 242                         elog(DEBUG, "ExecutorRun: Unknown feature %d", feature);
 243                         result = NULL;
 244                         break;
 245         }
 246
 247         (*destfunc->cleanup) (destfunc);
 248
 249         return result;
 250 }
 251
 252 /* ----------------------------------------------------------------
 253  *              ExecutorEnd
 254  *
 255  *              This routine must be called at the end of execution of any
 256  *              query plan
 257  * ----------------------------------------------------------------
 258  */
 259 void
 260 ExecutorEnd(QueryDesc *queryDesc, EState *estate)
 261 {
 262         /* sanity checks */
 263         Assert(queryDesc != NULL);
 264
 265         EndPlan(queryDesc->plantree, estate);
 266
 267         if (estate->es_snapshot != NULL)
 268         {
 269                 if (estate->es_snapshot->xcnt > 0)
 270                         pfree(estate->es_snapshot->xip);
 271                 pfree(estate->es_snapshot);
 272                 estate->es_snapshot = NULL;
 273         }
 274
 275         if (estate->es_param_exec_vals != NULL)
 276         {
 277                 pfree(estate->es_param_exec_vals);
 278                 estate->es_param_exec_vals = NULL;
 279         }
 280 }
 281
 282
 283 /*
 284  * ExecCheckQueryPerms
 285  *              Check access permissions for all relations referenced in a query.
 286  */
 287 static void
 288 ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan)
 289 {
 290
 291         /*
 292          * Check RTEs in the query's primary rangetable.
 293          */
 294         ExecCheckRTPerms(parseTree->rtable, operation);
 295
 296         /*
 297          * Search for subplans and APPEND nodes to check their rangetables.
 298          */
 299         ExecCheckPlanPerms(plan, parseTree->rtable, operation);
 300 }
 301
 302 /*
 303  * ExecCheckPlanPerms
 304  *              Recursively scan the plan tree to check access permissions in
 305  *              subplans.
 306  */
 307 static void
 308 ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation)
 309 {
 310         List       *subp;
 311
 312         if (plan == NULL)
 313                 return;
 314
 315         /* Check subplans, which we assume are plain SELECT queries */
 316
 317         foreach(subp, plan->initPlan)
 318         {
 319                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 320
 321                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 322                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 323         }
 324         foreach(subp, plan->subPlan)
 325         {
 326                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 327
 328                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 329                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 330         }
 331
 332         /* Check lower plan nodes */
 333
 334         ExecCheckPlanPerms(plan->lefttree, rangeTable, operation);
 335         ExecCheckPlanPerms(plan->righttree, rangeTable, operation);
 336
 337         /* Do node-type-specific checks */
 338
 339         switch (nodeTag(plan))
 340         {
 341                 case T_SubqueryScan:
 342                         {
 343                                 SubqueryScan *scan = (SubqueryScan *) plan;
 344                                 RangeTblEntry *rte;
 345
 346                                 /* Recursively check the subquery */
 347                                 rte = rt_fetch(scan->scan.scanrelid, rangeTable);
 348                                 Assert(rte->subquery != NULL);
 349                                 ExecCheckQueryPerms(operation, rte->subquery, scan->subplan);
 350                                 break;
 351                         }
 352                 case T_Append:
 353                         {
 354                                 Append     *app = (Append *) plan;
 355                                 List       *appendplans;
 356
 357                                 foreach(appendplans, app->appendplans)
 358                                 {
 359                                         ExecCheckPlanPerms((Plan *) lfirst(appendplans),
 360                                                                            rangeTable,
 361                                                                            operation);
 362                                 }
 363                                 break;
 364                         }
 365
 366                 default:
 367                         break;
 368         }
 369 }
 370
 371 /*
 372  * ExecCheckRTPerms
 373  *              Check access permissions for all relations listed in a range table.
 374  */
 375 static void
 376 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 377 {
 378         List       *lp;
 379
 380         foreach(lp, rangeTable)
 381         {
 382                 RangeTblEntry *rte = lfirst(lp);
 383
 384                 ExecCheckRTEPerms(rte, operation);
 385         }
 386 }
 387
 388 /*
 389  * ExecCheckRTEPerms
 390  *              Check access permissions for a single RTE.
 391  */
 392 static void
 393 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 394 {
 395         char       *relName;
 396         Oid                     userid;
 397         int32           aclcheck_result;
 398
 399         /*
 400          * If it's a subquery RTE, ignore it --- it will be checked when
 401          * ExecCheckPlanPerms finds the SubqueryScan node for it.
 402          */
 403         if (rte->subquery)
 404                 return;
 405
 406         relName = rte->relname;
 407
 408         /*
 409          * userid to check as: current user unless we have a setuid
 410          * indication.
 411          *
 412          * Note: GetUserId() is presently fast enough that there's no harm in
 413          * calling it separately for each RTE.  If that stops being true, we
 414          * could call it once in ExecCheckQueryPerms and pass the userid down
 415          * from there.  But for now, no need for the extra clutter.
 416          */
 417         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 418
 419 #define CHECK(MODE)             pg_aclcheck(relName, userid, MODE)
 420
 421         if (rte->checkForRead)
 422         {
 423                 aclcheck_result = CHECK(ACL_SELECT);
 424                 if (aclcheck_result != ACLCHECK_OK)
 425                         elog(ERROR, "%s: %s",
 426                                  relName, aclcheck_error_strings[aclcheck_result]);
 427         }
 428
 429         if (rte->checkForWrite)
 430         {
 431
 432                 /*
 433                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 434                  * Right now we don't distinguish that from true update as far as
 435                  * permissions checks are concerned.
 436                  */
 437                 switch (operation)
 438                 {
 439                         case CMD_INSERT:
 440                                 aclcheck_result = CHECK(ACL_INSERT);
 441                                 break;
 442                         case CMD_SELECT:
 443                         case CMD_UPDATE:
 444                                 aclcheck_result = CHECK(ACL_UPDATE);
 445                                 break;
 446                         case CMD_DELETE:
 447                                 aclcheck_result = CHECK(ACL_DELETE);
 448                                 break;
 449                         default:
 450                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 451                                          operation);
 452                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 453                                 break;
 454                 }
 455                 if (aclcheck_result != ACLCHECK_OK)
 456                         elog(ERROR, "%s: %s",
 457                                  relName, aclcheck_error_strings[aclcheck_result]);
 458         }
 459 }
 460
 461
 462 /* ===============================================================
 463  * ===============================================================
 464                                                  static routines follow
 465  * ===============================================================
 466  * ===============================================================
 467  */
 468
 469 typedef struct execRowMark
 470 {
 471         Relation        relation;
 472         Index           rti;
 473         char            resname[32];
 474 } execRowMark;
 475
 476 typedef struct evalPlanQual
 477 {
 478         Plan       *plan;
 479         Index           rti;
 480         EState          estate;
 481         struct evalPlanQual *free;
 482 } evalPlanQual;
 483
 484 /* ----------------------------------------------------------------
 485  *              InitPlan
 486  *
 487  *              Initializes the query plan: open files, allocate storage
 488  *              and start up the rule manager
 489  * ----------------------------------------------------------------
 490  */
 491 static TupleDesc
 492 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 493 {
 494         List       *rangeTable;
 495         Relation        intoRelationDesc;
 496         TupleDesc       tupType;
 497
 498         /*
 499          * Do permissions checks.
 500          */
 501         ExecCheckQueryPerms(operation, parseTree, plan);
 502
 503         /*
 504          * get information from query descriptor
 505          */
 506         rangeTable = parseTree->rtable;
 507
 508         /*
 509          * initialize the node's execution state
 510          */
 511         estate->es_range_table = rangeTable;
 512
 513         /*
 514          * if there is a result relation, initialize result relation stuff
 515          */
 516         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 517         {
 518                 List       *resultRelations = parseTree->resultRelations;
 519                 int                     numResultRelations;
 520                 ResultRelInfo *resultRelInfos;
 521
 522                 if (resultRelations != NIL)
 523                 {
 524
 525                         /*
 526                          * Multiple result relations (due to inheritance)
 527                          * parseTree->resultRelations identifies them all
 528                          */
 529                         ResultRelInfo *resultRelInfo;
 530
 531                         numResultRelations = length(resultRelations);
 532                         resultRelInfos = (ResultRelInfo *)
 533                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 534                         resultRelInfo = resultRelInfos;
 535                         while (resultRelations != NIL)
 536                         {
 537                                 initResultRelInfo(resultRelInfo,
 538                                                                   lfirsti(resultRelations),
 539                                                                   rangeTable,
 540                                                                   operation);
 541                                 resultRelInfo++;
 542                                 resultRelations = lnext(resultRelations);
 543                         }
 544                 }
 545                 else
 546                 {
 547
 548                         /*
 549                          * Single result relation identified by
 550                          * parseTree->resultRelation
 551                          */
 552                         numResultRelations = 1;
 553                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 554                         initResultRelInfo(resultRelInfos,
 555                                                           parseTree->resultRelation,
 556                                                           rangeTable,
 557                                                           operation);
 558                 }
 559
 560                 estate->es_result_relations = resultRelInfos;
 561                 estate->es_num_result_relations = numResultRelations;
 562                 /* Initialize to first or only result rel */
 563                 estate->es_result_relation_info = resultRelInfos;
 564         }
 565         else
 566         {
 567
 568                 /*
 569                  * if no result relation, then set state appropriately
 570                  */
 571                 estate->es_result_relations = NULL;
 572                 estate->es_num_result_relations = 0;
 573                 estate->es_result_relation_info = NULL;
 574         }
 575
 576         /*
 577          * Have to lock relations selected for update
 578          */
 579         estate->es_rowMark = NIL;
 580         if (parseTree->rowMarks != NIL)
 581         {
 582                 List       *l;
 583
 584                 foreach(l, parseTree->rowMarks)
 585                 {
 586                         Index           rti = lfirsti(l);
 587                         Oid                     relid = getrelid(rti, rangeTable);
 588                         Relation        relation;
 589                         execRowMark *erm;
 590
 591                         relation = heap_open(relid, RowShareLock);
 592                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 593                         erm->relation = relation;
 594                         erm->rti = rti;
 595                         sprintf(erm->resname, "ctid%u", rti);
 596                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 597                 }
 598         }
 599
 600         /*
 601          * initialize the executor "tuple" table.
 602          */
 603         {
 604                 int                     nSlots = ExecCountSlotsNode(plan);
 605
 606                 estate->es_tupleTable = ExecCreateTupleTable(nSlots + 10); /* why add ten? - jolly */
 607         }
 608
 609         /* mark EvalPlanQual not active */
 610         estate->es_origPlan = plan;
 611         estate->es_evalPlanQual = NULL;
 612         estate->es_evTuple = NULL;
 613         estate->es_evTupleNull = NULL;
 614         estate->es_useEvalPlan = false;
 615
 616         /*
 617          * initialize the private state information for all the nodes in the
 618          * query tree.  This opens files, allocates storage and leaves us
 619          * ready to start processing tuples.
 620          */
 621         ExecInitNode(plan, estate, NULL);
 622
 623         /*
 624          * Get the tuple descriptor describing the type of tuples to return.
 625          * (this is especially important if we are creating a relation with
 626          * "retrieve into")
 627          */
 628         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 629
 630         /*
 631          * Initialize the junk filter if needed. SELECT and INSERT queries
 632          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 633          * DELETE always need one, since there's always a junk 'ctid'
 634          * attribute present --- no need to look first.
 635          */
 636         {
 637                 bool            junk_filter_needed = false;
 638                 List       *tlist;
 639
 640                 switch (operation)
 641                 {
 642                         case CMD_SELECT:
 643                         case CMD_INSERT:
 644                                 foreach(tlist, plan->targetlist)
 645                                 {
 646                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 647
 648                                         if (tle->resdom->resjunk)
 649                                         {
 650                                                 junk_filter_needed = true;
 651                                                 break;
 652                                         }
 653                                 }
 654                                 break;
 655                         case CMD_UPDATE:
 656                         case CMD_DELETE:
 657                                 junk_filter_needed = true;
 658                                 break;
 659                         default:
 660                                 break;
 661                 }
 662
 663                 if (junk_filter_needed)
 664                 {
 665
 666                         /*
 667                          * If there are multiple result relations, each one needs its
 668                          * own junk filter.  Note this is only possible for
 669                          * UPDATE/DELETE, so we can't be fooled by some needing a
 670                          * filter and some not.
 671                          */
 672                         if (parseTree->resultRelations != NIL)
 673                         {
 674                                 List       *subplans;
 675                                 ResultRelInfo *resultRelInfo;
 676
 677                                 /* Top plan had better be an Append here. */
 678                                 Assert(IsA(plan, Append));
 679                                 Assert(((Append *) plan)->isTarget);
 680                                 subplans = ((Append *) plan)->appendplans;
 681                                 Assert(length(subplans) == estate->es_num_result_relations);
 682                                 resultRelInfo = estate->es_result_relations;
 683                                 while (subplans != NIL)
 684                                 {
 685                                         Plan       *subplan = (Plan *) lfirst(subplans);
 686                                         JunkFilter *j;
 687
 688                                         j = ExecInitJunkFilter(subplan->targetlist,
 689                                                                                    ExecGetTupType(subplan));
 690                                         resultRelInfo->ri_junkFilter = j;
 691                                         resultRelInfo++;
 692                                         subplans = lnext(subplans);
 693                                 }
 694
 695                                 /*
 696                                  * Set active junkfilter too; at this point ExecInitAppend
 697                                  * has already selected an active result relation...
 698                                  */
 699                                 estate->es_junkFilter =
 700                                         estate->es_result_relation_info->ri_junkFilter;
 701                         }
 702                         else
 703                         {
 704                                 /* Normal case with just one JunkFilter */
 705                                 JunkFilter *j = ExecInitJunkFilter(plan->targetlist,
 706                                                                                                    tupType);
 707
 708                                 estate->es_junkFilter = j;
 709                                 if (estate->es_result_relation_info)
 710                                         estate->es_result_relation_info->ri_junkFilter = j;
 711
 712                                 /* For SELECT, want to return the cleaned tuple type */
 713                                 if (operation == CMD_SELECT)
 714                                         tupType = j->jf_cleanTupType;
 715                         }
 716                 }
 717                 else
 718                         estate->es_junkFilter = NULL;
 719         }
 720
 721         /*
 722          * initialize the "into" relation
 723          */
 724         intoRelationDesc = (Relation) NULL;
 725
 726         if (operation == CMD_SELECT)
 727         {
 728                 char       *intoName;
 729                 Oid                     intoRelationId;
 730                 TupleDesc       tupdesc;
 731
 732                 if (!parseTree->isPortal)
 733                 {
 734
 735                         /*
 736                          * a select into table
 737                          */
 738                         if (parseTree->into != NULL)
 739                         {
 740
 741                                 /*
 742                                  * create the "into" relation
 743                                  */
 744                                 intoName = parseTree->into;
 745
 746                                 /*
 747                                  * have to copy tupType to get rid of constraints
 748                                  */
 749                                 tupdesc = CreateTupleDescCopy(tupType);
 750
 751                                 intoRelationId =
 752                                         heap_create_with_catalog(intoName,
 753                                                                                          tupdesc,
 754                                                                                          RELKIND_RELATION,
 755                                                                                          parseTree->isTemp,
 756                                                                                          allowSystemTableMods);
 757
 758                                 FreeTupleDesc(tupdesc);
 759
 760                                 /*
 761                                  * Advance command counter so that the newly-created
 762                                  * relation's catalog tuples will be visible to heap_open.
 763                                  */
 764                                 CommandCounterIncrement();
 765
 766                                 /*
 767                                  * If necessary, create a TOAST table for the into
 768                                  * relation. Note that AlterTableCreateToastTable ends
 769                                  * with CommandCounterIncrement(), so that the TOAST table
 770                                  * will be visible for insertion.
 771                                  */
 772                                 AlterTableCreateToastTable(intoName, true);
 773
 774                                 intoRelationDesc = heap_open(intoRelationId,
 775                                                                                          AccessExclusiveLock);
 776                         }
 777                 }
 778         }
 779
 780         estate->es_into_relation_descriptor = intoRelationDesc;
 781
 782         return tupType;
 783 }
 784
 785 /*
 786  * Initialize ResultRelInfo data for one result relation
 787  */
 788 static void
 789 initResultRelInfo(ResultRelInfo *resultRelInfo,
 790                                   Index resultRelationIndex,
 791                                   List *rangeTable,
 792                                   CmdType operation)
 793 {
 794         Oid                     resultRelationOid;
 795         Relation        resultRelationDesc;
 796
 797         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 798         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 799
 800         switch (resultRelationDesc->rd_rel->relkind)
 801         {
 802                 case RELKIND_SEQUENCE:
 803                         elog(ERROR, "You can't change sequence relation %s",
 804                                  RelationGetRelationName(resultRelationDesc));
 805                         break;
 806                 case RELKIND_TOASTVALUE:
 807                         elog(ERROR, "You can't change toast relation %s",
 808                                  RelationGetRelationName(resultRelationDesc));
 809                         break;
 810                 case RELKIND_VIEW:
 811                         elog(ERROR, "You can't change view relation %s",
 812                                  RelationGetRelationName(resultRelationDesc));
 813                         break;
 814         }
 815
 816         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 817         resultRelInfo->type = T_ResultRelInfo;
 818         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 819         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 820         resultRelInfo->ri_NumIndices = 0;
 821         resultRelInfo->ri_IndexRelationDescs = NULL;
 822         resultRelInfo->ri_IndexRelationInfo = NULL;
 823         resultRelInfo->ri_ConstraintExprs = NULL;
 824         resultRelInfo->ri_junkFilter = NULL;
 825
 826         /*
 827          * If there are indices on the result relation, open them and save
 828          * descriptors in the result relation info, so that we can add new
 829          * index entries for the tuples we add/update.  We need not do this
 830          * for a DELETE, however, since deletion doesn't affect indexes.
 831          */
 832         if (resultRelationDesc->rd_rel->relhasindex &&
 833                 operation != CMD_DELETE)
 834                 ExecOpenIndices(resultRelInfo);
 835 }
 836
 837 /* ----------------------------------------------------------------
 838  *              EndPlan
 839  *
 840  *              Cleans up the query plan -- closes files and free up storages
 841  * ----------------------------------------------------------------
 842  */
 843 static void
 844 EndPlan(Plan *plan, EState *estate)
 845 {
 846         ResultRelInfo *resultRelInfo;
 847         int                     i;
 848         List       *l;
 849
 850         /*
 851          * shut down any PlanQual processing we were doing
 852          */
 853         if (estate->es_evalPlanQual != NULL)
 854                 EndEvalPlanQual(estate);
 855
 856         /*
 857          * shut down the node-type-specific query processing
 858          */
 859         ExecEndNode(plan, plan);
 860
 861         /*
 862          * destroy the executor "tuple" table.
 863          */
 864         ExecDropTupleTable(estate->es_tupleTable, true);
 865         estate->es_tupleTable = NULL;
 866
 867         /*
 868          * close the result relation(s) if any, but hold locks until xact
 869          * commit.      Also clean up junkfilters if present.
 870          */
 871         resultRelInfo = estate->es_result_relations;
 872         for (i = estate->es_num_result_relations; i > 0; i--)
 873         {
 874                 /* Close indices and then the relation itself */
 875                 ExecCloseIndices(resultRelInfo);
 876                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 877                 /* Delete the junkfilter if any */
 878                 if (resultRelInfo->ri_junkFilter != NULL)
 879                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 880                 resultRelInfo++;
 881         }
 882
 883         /*
 884          * close the "into" relation if necessary, again keeping lock
 885          */
 886         if (estate->es_into_relation_descriptor != NULL)
 887                 heap_close(estate->es_into_relation_descriptor, NoLock);
 888
 889         /*
 890          * There might be a junkfilter without a result relation.
 891          */
 892         if (estate->es_num_result_relations == 0 &&
 893                 estate->es_junkFilter != NULL)
 894         {
 895                 ExecFreeJunkFilter(estate->es_junkFilter);
 896                 estate->es_junkFilter = NULL;
 897         }
 898
 899         /*
 900          * close any relations selected FOR UPDATE, again keeping locks
 901          */
 902         foreach(l, estate->es_rowMark)
 903         {
 904                 execRowMark *erm = lfirst(l);
 905
 906                 heap_close(erm->relation, NoLock);
 907         }
 908 }
 909
 910 /* ----------------------------------------------------------------
 911  *              ExecutePlan
 912  *
 913  *              processes the query plan to retrieve 'numberTuples' tuples in the
 914  *              direction specified.
 915  *              Retrieves all tuples if tupleCount is 0
 916  *
 917  *              result is either a slot containing the last tuple in the case
 918  *              of a RETRIEVE or NULL otherwise.
 919  *
 920  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 921  * user can see it
 922  * ----------------------------------------------------------------
 923  */
 924 static TupleTableSlot *
 925 ExecutePlan(EState *estate,
 926                         Plan *plan,
 927                         CmdType operation,
 928                         long numberTuples,
 929                         ScanDirection direction,
 930                         DestReceiver *destfunc)
 931 {
 932         JunkFilter *junkfilter;
 933         TupleTableSlot *slot;
 934         ItemPointer tupleid = NULL;
 935         ItemPointerData tuple_ctid;
 936         long            current_tuple_count;
 937         TupleTableSlot *result;
 938
 939         /*
 940          * initialize local variables
 941          */
 942         slot = NULL;
 943         current_tuple_count = 0;
 944         result = NULL;
 945
 946         /*
 947          * Set the direction.
 948          */
 949         estate->es_direction = direction;
 950
 951         /*
 952          * Loop until we've processed the proper number of tuples from the
 953          * plan.
 954          */
 955
 956         for (;;)
 957         {
 958                 /* Reset the per-output-tuple exprcontext */
 959                 ResetPerTupleExprContext(estate);
 960
 961                 /*
 962                  * Execute the plan and obtain a tuple
 963                  */
 964                 /* at the top level, the parent of a plan (2nd arg) is itself */
 965 lnext:  ;
 966                 if (estate->es_useEvalPlan)
 967                 {
 968                         slot = EvalPlanQualNext(estate);
 969                         if (TupIsNull(slot))
 970                                 slot = ExecProcNode(plan, plan);
 971                 }
 972                 else
 973                         slot = ExecProcNode(plan, plan);
 974
 975                 /*
 976                  * if the tuple is null, then we assume there is nothing more to
 977                  * process so we just return null...
 978                  */
 979                 if (TupIsNull(slot))
 980                 {
 981                         result = NULL;
 982                         break;
 983                 }
 984
 985                 /*
 986                  * if we have a junk filter, then project a new tuple with the
 987                  * junk removed.
 988                  *
 989                  * Store this new "clean" tuple in the place of the original tuple.
 990                  *
 991                  * Also, extract all the junk information we need.
 992                  */
 993                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 994                 {
 995                         Datum           datum;
 996                         HeapTuple       newTuple;
 997                         bool            isNull;
 998
 999                         /*
1000                          * extract the 'ctid' junk attribute.
1001                          */
1002                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1003                         {
1004                                 if (!ExecGetJunkAttribute(junkfilter,
1005                                                                                   slot,
1006                                                                                   "ctid",
1007                                                                                   &datum,
1008                                                                                   &isNull))
1009                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1010
1011                                 /* shouldn't ever get a null result... */
1012                                 if (isNull)
1013                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1014
1015                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1016                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1017                                                                                  * ctid!! */
1018                                 tupleid = &tuple_ctid;
1019                         }
1020                         else if (estate->es_rowMark != NIL)
1021                         {
1022                                 List       *l;
1023
1024                 lmark:  ;
1025                                 foreach(l, estate->es_rowMark)
1026                                 {
1027                                         execRowMark *erm = lfirst(l);
1028                                         Buffer          buffer;
1029                                         HeapTupleData tuple;
1030                                         TupleTableSlot *newSlot;
1031                                         int                     test;
1032
1033                                         if (!ExecGetJunkAttribute(junkfilter,
1034                                                                                           slot,
1035                                                                                           erm->resname,
1036                                                                                           &datum,
1037                                                                                           &isNull))
1038                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1039                                                          erm->resname);
1040
1041                                         /* shouldn't ever get a null result... */
1042                                         if (isNull)
1043                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1044                                                          erm->resname);
1045
1046                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1047                                         test = heap_mark4update(erm->relation, &tuple, &buffer);
1048                                         ReleaseBuffer(buffer);
1049                                         switch (test)
1050                                         {
1051                                                 case HeapTupleSelfUpdated:
1052                                                 case HeapTupleMayBeUpdated:
1053                                                         break;
1054
1055                                                 case HeapTupleUpdated:
1056                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1057                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1058                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1059                                                                   (ItemPointer) DatumGetPointer(datum))))
1060                                                         {
1061                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1062                                                                 if (!(TupIsNull(newSlot)))
1063                                                                 {
1064                                                                         slot = newSlot;
1065                                                                         estate->es_useEvalPlan = true;
1066                                                                         goto lmark;
1067                                                                 }
1068                                                         }
1069
1070                                                         /*
1071                                                          * if tuple was deleted or PlanQual failed for
1072                                                          * updated tuple - we must not return this
1073                                                          * tuple!
1074                                                          */
1075                                                         goto lnext;
1076
1077                                                 default:
1078                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1079                                                         return (NULL);
1080                                         }
1081                                 }
1082                         }
1083
1084                         /*
1085                          * Finally create a new "clean" tuple with all junk attributes
1086                          * removed
1087                          */
1088                         newTuple = ExecRemoveJunk(junkfilter, slot);
1089
1090                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1091                                                                   slot, /* destination slot */
1092                                                                   InvalidBuffer,                /* this tuple has no
1093                                                                                                                  * buffer */
1094                                                                   true);                /* tuple should be pfreed */
1095                 }                                               /* if (junkfilter... */
1096
1097                 /*
1098                  * now that we have a tuple, do the appropriate thing with it..
1099                  * either return it to the user, add it to a relation someplace,
1100                  * delete it from a relation, or modify some of its attributes.
1101                  */
1102
1103                 switch (operation)
1104                 {
1105                         case CMD_SELECT:
1106                                 ExecRetrieve(slot,              /* slot containing tuple */
1107                                                          destfunc,      /* destination's tuple-receiver
1108                                                                                  * obj */
1109                                                          estate);       /* */
1110                                 result = slot;
1111                                 break;
1112
1113                         case CMD_INSERT:
1114                                 ExecAppend(slot, tupleid, estate);
1115                                 result = NULL;
1116                                 break;
1117
1118                         case CMD_DELETE:
1119                                 ExecDelete(slot, tupleid, estate);
1120                                 result = NULL;
1121                                 break;
1122
1123                         case CMD_UPDATE:
1124                                 ExecReplace(slot, tupleid, estate);
1125                                 result = NULL;
1126                                 break;
1127
1128                         default:
1129                                 elog(DEBUG, "ExecutePlan: unknown operation in queryDesc");
1130                                 result = NULL;
1131                                 break;
1132                 }
1133
1134                 /*
1135                  * check our tuple count.. if we've processed the proper number
1136                  * then quit, else loop again and process more tuples..
1137                  */
1138                 current_tuple_count++;
1139                 if (numberTuples == current_tuple_count)
1140                         break;
1141         }
1142
1143         /*
1144          * here, result is either a slot containing a tuple in the case of a
1145          * RETRIEVE or NULL otherwise.
1146          */
1147         return result;
1148 }
1149
1150 /* ----------------------------------------------------------------
1151  *              ExecRetrieve
1152  *
1153  *              RETRIEVEs are easy.. we just pass the tuple to the appropriate
1154  *              print function.  The only complexity is when we do a
1155  *              "retrieve into", in which case we insert the tuple into
1156  *              the appropriate relation (note: this is a newly created relation
1157  *              so we don't need to worry about indices or locks.)
1158  * ----------------------------------------------------------------
1159  */
1160 static void
1161 ExecRetrieve(TupleTableSlot *slot,
1162                          DestReceiver *destfunc,
1163                          EState *estate)
1164 {
1165         HeapTuple       tuple;
1166         TupleDesc       attrtype;
1167
1168         /*
1169          * get the heap tuple out of the tuple table slot
1170          */
1171         tuple = slot->val;
1172         attrtype = slot->ttc_tupleDescriptor;
1173
1174         /*
1175          * insert the tuple into the "into relation"
1176          */
1177         if (estate->es_into_relation_descriptor != NULL)
1178         {
1179                 heap_insert(estate->es_into_relation_descriptor, tuple);
1180                 IncrAppended();
1181         }
1182
1183         /*
1184          * send the tuple to the front end (or the screen)
1185          */
1186         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1187         IncrRetrieved();
1188         (estate->es_processed)++;
1189 }
1190
1191 /* ----------------------------------------------------------------
1192  *              ExecAppend
1193  *
1194  *              APPENDs are trickier.. we have to insert the tuple into
1195  *              the base relation and insert appropriate tuples into the
1196  *              index relations.
1197  * ----------------------------------------------------------------
1198  */
1199
1200 static void
1201 ExecAppend(TupleTableSlot *slot,
1202                    ItemPointer tupleid,
1203                    EState *estate)
1204 {
1205         HeapTuple       tuple;
1206         ResultRelInfo *resultRelInfo;
1207         Relation        resultRelationDesc;
1208         int                     numIndices;
1209         Oid                     newId;
1210
1211         /*
1212          * get the heap tuple out of the tuple table slot
1213          */
1214         tuple = slot->val;
1215
1216         /*
1217          * get information on the (current) result relation
1218          */
1219         resultRelInfo = estate->es_result_relation_info;
1220         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1221
1222         /* BEFORE ROW INSERT Triggers */
1223         if (resultRelationDesc->trigdesc &&
1224         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1225         {
1226                 HeapTuple       newtuple;
1227
1228                 newtuple = ExecBRInsertTriggers(estate, resultRelationDesc, tuple);
1229
1230                 if (newtuple == NULL)   /* "do nothing" */
1231                         return;
1232
1233                 if (newtuple != tuple)  /* modified by Trigger(s) */
1234                 {
1235
1236                         /*
1237                          * Insert modified tuple into tuple table slot, replacing the
1238                          * original.  We assume that it was allocated in per-tuple
1239                          * memory context, and therefore will go away by itself. The
1240                          * tuple table slot should not try to clear it.
1241                          */
1242                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1243                         tuple = newtuple;
1244                 }
1245         }
1246
1247         /*
1248          * Check the constraints of the tuple
1249          */
1250         if (resultRelationDesc->rd_att->constr)
1251                 ExecConstraints("ExecAppend", resultRelInfo, slot, estate);
1252
1253         /*
1254          * insert the tuple
1255          */
1256         newId = heap_insert(resultRelationDesc, tuple);
1257
1258         IncrAppended();
1259         (estate->es_processed)++;
1260         estate->es_lastoid = newId;
1261
1262         /*
1263          * process indices
1264          *
1265          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1266          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1267          * field.
1268          */
1269         numIndices = resultRelInfo->ri_NumIndices;
1270         if (numIndices > 0)
1271                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1272
1273         /* AFTER ROW INSERT Triggers */
1274         if (resultRelationDesc->trigdesc)
1275                 ExecARInsertTriggers(estate, resultRelationDesc, tuple);
1276 }
1277
1278 /* ----------------------------------------------------------------
1279  *              ExecDelete
1280  *
1281  *              DELETE is like append, we delete the tuple and its
1282  *              index tuples.
1283  * ----------------------------------------------------------------
1284  */
1285 static void
1286 ExecDelete(TupleTableSlot *slot,
1287                    ItemPointer tupleid,
1288                    EState *estate)
1289 {
1290         ResultRelInfo *resultRelInfo;
1291         Relation        resultRelationDesc;
1292         ItemPointerData ctid;
1293         int                     result;
1294
1295         /*
1296          * get information on the (current) result relation
1297          */
1298         resultRelInfo = estate->es_result_relation_info;
1299         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1300
1301         /* BEFORE ROW DELETE Triggers */
1302         if (resultRelationDesc->trigdesc &&
1303         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1304         {
1305                 bool            dodelete;
1306
1307                 dodelete = ExecBRDeleteTriggers(estate, tupleid);
1308
1309                 if (!dodelete)                  /* "do nothing" */
1310                         return;
1311         }
1312
1313         /*
1314          * delete the tuple
1315          */
1316 ldelete:;
1317         result = heap_delete(resultRelationDesc, tupleid, &ctid);
1318         switch (result)
1319         {
1320                 case HeapTupleSelfUpdated:
1321                         return;
1322
1323                 case HeapTupleMayBeUpdated:
1324                         break;
1325
1326                 case HeapTupleUpdated:
1327                         if (XactIsoLevel == XACT_SERIALIZABLE)
1328                                 elog(ERROR, "Can't serialize access due to concurrent update");
1329                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1330                         {
1331                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1332                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1333
1334                                 if (!TupIsNull(epqslot))
1335                                 {
1336                                         *tupleid = ctid;
1337                                         goto ldelete;
1338                                 }
1339                         }
1340                         /* tuple already deleted; nothing to do */
1341                         return;
1342
1343                 default:
1344                         elog(ERROR, "Unknown status %u from heap_delete", result);
1345                         return;
1346         }
1347
1348         IncrDeleted();
1349         (estate->es_processed)++;
1350
1351         /*
1352          * Note: Normally one would think that we have to delete index tuples
1353          * associated with the heap tuple now..
1354          *
1355          * ... but in POSTGRES, we have no need to do this because the vacuum
1356          * daemon automatically opens an index scan and deletes index tuples
1357          * when it finds deleted heap tuples. -cim 9/27/89
1358          */
1359
1360         /* AFTER ROW DELETE Triggers */
1361         if (resultRelationDesc->trigdesc)
1362                 ExecARDeleteTriggers(estate, tupleid);
1363 }
1364
1365 /* ----------------------------------------------------------------
1366  *              ExecReplace
1367  *
1368  *              note: we can't run replace queries with transactions
1369  *              off because replaces are actually appends and our
1370  *              scan will mistakenly loop forever, replacing the tuple
1371  *              it just appended..      This should be fixed but until it
1372  *              is, we don't want to get stuck in an infinite loop
1373  *              which corrupts your database..
1374  * ----------------------------------------------------------------
1375  */
1376 static void
1377 ExecReplace(TupleTableSlot *slot,
1378                         ItemPointer tupleid,
1379                         EState *estate)
1380 {
1381         HeapTuple       tuple;
1382         ResultRelInfo *resultRelInfo;
1383         Relation        resultRelationDesc;
1384         ItemPointerData ctid;
1385         int                     result;
1386         int                     numIndices;
1387
1388         /*
1389          * abort the operation if not running transactions
1390          */
1391         if (IsBootstrapProcessingMode())
1392         {
1393                 elog(NOTICE, "ExecReplace: replace can't run without transactions");
1394                 return;
1395         }
1396
1397         /*
1398          * get the heap tuple out of the tuple table slot
1399          */
1400         tuple = slot->val;
1401
1402         /*
1403          * get information on the (current) result relation
1404          */
1405         resultRelInfo = estate->es_result_relation_info;
1406         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1407
1408         /* BEFORE ROW UPDATE Triggers */
1409         if (resultRelationDesc->trigdesc &&
1410         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1411         {
1412                 HeapTuple       newtuple;
1413
1414                 newtuple = ExecBRUpdateTriggers(estate, tupleid, tuple);
1415
1416                 if (newtuple == NULL)   /* "do nothing" */
1417                         return;
1418
1419                 if (newtuple != tuple)  /* modified by Trigger(s) */
1420                 {
1421
1422                         /*
1423                          * Insert modified tuple into tuple table slot, replacing the
1424                          * original.  We assume that it was allocated in per-tuple
1425                          * memory context, and therefore will go away by itself. The
1426                          * tuple table slot should not try to clear it.
1427                          */
1428                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1429                         tuple = newtuple;
1430                 }
1431         }
1432
1433         /*
1434          * Check the constraints of the tuple
1435          *
1436          * If we generate a new candidate tuple after EvalPlanQual testing,
1437          * we must loop back here and recheck constraints.  (We don't need to
1438          * redo triggers, however.  If there are any BEFORE triggers then
1439          * trigger.c will have done mark4update to lock the correct tuple,
1440          * so there's no need to do them again.)
1441          */
1442 lreplace:;
1443         if (resultRelationDesc->rd_att->constr)
1444                 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1445
1446         /*
1447          * replace the heap tuple
1448          */
1449         result = heap_update(resultRelationDesc, tupleid, tuple, &ctid);
1450         switch (result)
1451         {
1452                 case HeapTupleSelfUpdated:
1453                         return;
1454
1455                 case HeapTupleMayBeUpdated:
1456                         break;
1457
1458                 case HeapTupleUpdated:
1459                         if (XactIsoLevel == XACT_SERIALIZABLE)
1460                                 elog(ERROR, "Can't serialize access due to concurrent update");
1461                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1462                         {
1463                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1464                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1465
1466                                 if (!TupIsNull(epqslot))
1467                                 {
1468                                         *tupleid = ctid;
1469                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1470                                         slot = ExecStoreTuple(tuple, slot, InvalidBuffer, true);
1471                                         goto lreplace;
1472                                 }
1473                         }
1474                         /* tuple already deleted; nothing to do */
1475                         return;
1476
1477                 default:
1478                         elog(ERROR, "Unknown status %u from heap_update", result);
1479                         return;
1480         }
1481
1482         IncrReplaced();
1483         (estate->es_processed)++;
1484
1485         /*
1486          * Note: instead of having to update the old index tuples associated
1487          * with the heap tuple, all we do is form and insert new index tuples.
1488          * This is because replaces are actually deletes and inserts and index
1489          * tuple deletion is done automagically by the vacuum daemon. All we
1490          * do is insert new index tuples.  -cim 9/27/89
1491          */
1492
1493         /*
1494          * process indices
1495          *
1496          * heap_update updates a tuple in the base relation by invalidating it
1497          * and then appending a new tuple to the relation.      As a side effect,
1498          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1499          * field.  So we now insert index tuples using the new tupleid stored
1500          * there.
1501          */
1502
1503         numIndices = resultRelInfo->ri_NumIndices;
1504         if (numIndices > 0)
1505                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, true);
1506
1507         /* AFTER ROW UPDATE Triggers */
1508         if (resultRelationDesc->trigdesc)
1509                 ExecARUpdateTriggers(estate, tupleid, tuple);
1510 }
1511
1512 static char *
1513 ExecRelCheck(ResultRelInfo *resultRelInfo,
1514                          TupleTableSlot *slot, EState *estate)
1515 {
1516         Relation        rel = resultRelInfo->ri_RelationDesc;
1517         int                     ncheck = rel->rd_att->constr->num_check;
1518         ConstrCheck *check = rel->rd_att->constr->check;
1519         ExprContext *econtext;
1520         MemoryContext oldContext;
1521         List       *qual;
1522         int                     i;
1523
1524         /*
1525          * If first time through for this result relation, build expression
1526          * nodetrees for rel's constraint expressions.  Keep them in the
1527          * per-query memory context so they'll survive throughout the query.
1528          */
1529         if (resultRelInfo->ri_ConstraintExprs == NULL)
1530         {
1531                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1532                 resultRelInfo->ri_ConstraintExprs =
1533                         (List **) palloc(ncheck * sizeof(List *));
1534                 for (i = 0; i < ncheck; i++)
1535                 {
1536                         qual = (List *) stringToNode(check[i].ccbin);
1537                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1538                 }
1539                 MemoryContextSwitchTo(oldContext);
1540         }
1541
1542         /*
1543          * We will use the EState's per-tuple context for evaluating
1544          * constraint expressions (creating it if it's not already there).
1545          */
1546         econtext = GetPerTupleExprContext(estate);
1547
1548         /* Arrange for econtext's scan tuple to be the tuple under test */
1549         econtext->ecxt_scantuple = slot;
1550
1551         /* And evaluate the constraints */
1552         for (i = 0; i < ncheck; i++)
1553         {
1554                 qual = resultRelInfo->ri_ConstraintExprs[i];
1555
1556                 /*
1557                  * NOTE: SQL92 specifies that a NULL result from a constraint
1558                  * expression is not to be treated as a failure.  Therefore, tell
1559                  * ExecQual to return TRUE for NULL.
1560                  */
1561                 if (!ExecQual(qual, econtext, true))
1562                         return check[i].ccname;
1563         }
1564
1565         /* NULL result means no error */
1566         return (char *) NULL;
1567 }
1568
1569 void
1570 ExecConstraints(char *caller, ResultRelInfo *resultRelInfo,
1571                                 TupleTableSlot *slot, EState *estate)
1572 {
1573         Relation        rel = resultRelInfo->ri_RelationDesc;
1574         HeapTuple       tuple = slot->val;
1575         TupleConstr *constr = rel->rd_att->constr;
1576
1577         Assert(constr);
1578
1579         if (constr->has_not_null)
1580         {
1581                 int                     natts = rel->rd_att->natts;
1582                 int                     attrChk;
1583
1584                 for (attrChk = 1; attrChk <= natts; attrChk++)
1585                 {
1586                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1587                                 heap_attisnull(tuple, attrChk))
1588                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1589                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1590                 }
1591         }
1592
1593         if (constr->num_check > 0)
1594         {
1595                 char       *failed;
1596
1597                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1598                         elog(ERROR, "%s: rejected due to CHECK constraint %s",
1599                                  caller, failed);
1600         }
1601 }
1602
1603 /*
1604  * Check a modified tuple to see if we want to process its updated version
1605  * under READ COMMITTED rules.
1606  *
1607  * See backend/executor/README for some info about how this works.
1608  */
1609 TupleTableSlot *
1610 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1611 {
1612         evalPlanQual *epq;
1613         EState     *epqstate;
1614         Relation        relation;
1615         HeapTupleData tuple;
1616         HeapTuple       copyTuple = NULL;
1617         int                     rtsize;
1618         bool            endNode;
1619
1620         Assert(rti != 0);
1621
1622         /*
1623          * find relation containing target tuple
1624          */
1625         if (estate->es_result_relation_info != NULL &&
1626                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1627         {
1628                 relation = estate->es_result_relation_info->ri_RelationDesc;
1629         }
1630         else
1631         {
1632                 List       *l;
1633
1634                 relation = NULL;
1635                 foreach(l, estate->es_rowMark)
1636                 {
1637                         if (((execRowMark *) lfirst(l))->rti == rti)
1638                         {
1639                                 relation = ((execRowMark *) lfirst(l))->relation;
1640                                 break;
1641                         }
1642                 }
1643                 if (relation == NULL)
1644                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1645         }
1646
1647         /*
1648          * fetch tid tuple
1649          *
1650          * Loop here to deal with updated or busy tuples
1651          */
1652         tuple.t_self = *tid;
1653         for (;;)
1654         {
1655                 Buffer          buffer;
1656
1657                 heap_fetch(relation, SnapshotDirty, &tuple, &buffer);
1658                 if (tuple.t_data != NULL)
1659                 {
1660                         TransactionId xwait = SnapshotDirty->xmax;
1661
1662                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1663                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1664
1665                         /*
1666                          * If tuple is being updated by other transaction then we have
1667                          * to wait for its commit/abort.
1668                          */
1669                         if (TransactionIdIsValid(xwait))
1670                         {
1671                                 ReleaseBuffer(buffer);
1672                                 XactLockTableWait(xwait);
1673                                 continue;
1674                         }
1675
1676                         /*
1677                          * We got tuple - now copy it for use by recheck query.
1678                          */
1679                         copyTuple = heap_copytuple(&tuple);
1680                         ReleaseBuffer(buffer);
1681                         break;
1682                 }
1683
1684                 /*
1685                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1686                  * Note that it's possible to get invalid SnapshotDirty->tid if
1687                  * tuple updated by this transaction. Have we to check this ?
1688                  */
1689                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1690                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1691                 {
1692                         /* updated, so look at the updated copy */
1693                         tuple.t_self = SnapshotDirty->tid;
1694                         continue;
1695                 }
1696
1697                 /*
1698                  * Deleted or updated by this transaction; forget it.
1699                  */
1700                 return NULL;
1701         }
1702
1703         /*
1704          * For UPDATE/DELETE we have to return tid of actual row we're
1705          * executing PQ for.
1706          */
1707         *tid = tuple.t_self;
1708
1709         /*
1710          * Need to run a recheck subquery.  Find or create a PQ stack entry.
1711          */
1712         epq = (evalPlanQual *) estate->es_evalPlanQual;
1713         rtsize = length(estate->es_range_table);
1714         endNode = true;
1715
1716         if (epq != NULL && epq->rti == 0)
1717         {
1718                 /* Top PQ stack entry is idle, so re-use it */
1719                 Assert(!(estate->es_useEvalPlan) &&
1720                            epq->estate.es_evalPlanQual == NULL);
1721                 epq->rti = rti;
1722                 endNode = false;
1723         }
1724
1725         /*
1726          * If this is request for another RTE - Ra, - then we have to check
1727          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1728          * updated again and we have to re-start old execution for Ra and
1729          * forget all what we done after Ra was suspended. Cool? -:))
1730          */
1731         if (epq != NULL && epq->rti != rti &&
1732                 epq->estate.es_evTuple[rti - 1] != NULL)
1733         {
1734                 do
1735                 {
1736                         evalPlanQual *oldepq;
1737
1738                         /* pop previous PlanQual from the stack */
1739                         epqstate = &(epq->estate);
1740                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1741                         Assert(oldepq->rti != 0);
1742                         /* stop execution */
1743                         ExecEndNode(epq->plan, epq->plan);
1744                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1745                         epqstate->es_tupleTable = NULL;
1746                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1747                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1748                         /* push current PQ to freePQ stack */
1749                         oldepq->free = epq;
1750                         epq = oldepq;
1751                         estate->es_evalPlanQual = (Pointer) epq;
1752                 } while (epq->rti != rti);
1753         }
1754
1755         /*
1756          * If we are requested for another RTE then we have to suspend
1757          * execution of current PlanQual and start execution for new one.
1758          */
1759         if (epq == NULL || epq->rti != rti)
1760         {
1761                 /* try to reuse plan used previously */
1762                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1763
1764                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1765                 {
1766                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1767                         newepq->free = NULL;
1768                         /*
1769                          * Each stack level has its own copy of the plan tree.  This
1770                          * is wasteful, but necessary as long as plan nodes point to
1771                          * exec state nodes rather than vice versa.  Note that copyfuncs.c
1772                          * doesn't attempt to copy the exec state nodes, which is a good
1773                          * thing in this situation.
1774                          */
1775                         newepq->plan = copyObject(estate->es_origPlan);
1776                         /*
1777                          * Init stack level's EState.  We share top level's copy of
1778                          * es_result_relations array and other non-changing status.
1779                          * We need our own tupletable, es_param_exec_vals, and other
1780                          * changeable state.
1781                          */
1782                         epqstate = &(newepq->estate);
1783                         memcpy(epqstate, estate, sizeof(EState));
1784                         epqstate->es_direction = ForwardScanDirection;
1785                         if (estate->es_origPlan->nParamExec > 0)
1786                                 epqstate->es_param_exec_vals = (ParamExecData *)
1787                                         palloc(estate->es_origPlan->nParamExec *
1788                                                    sizeof(ParamExecData));
1789                         epqstate->es_tupleTable = NULL;
1790                         epqstate->es_per_tuple_exprcontext = NULL;
1791                         /*
1792                          * Each epqstate must have its own es_evTupleNull state,
1793                          * but all the stack entries share es_evTuple state.  This
1794                          * allows sub-rechecks to inherit the value being examined by
1795                          * an outer recheck.
1796                          */
1797                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1798                         if (epq == NULL)
1799                         {
1800                                 /* first PQ stack entry */
1801                                 epqstate->es_evTuple = (HeapTuple *)
1802                                         palloc(rtsize * sizeof(HeapTuple));
1803                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1804                         }
1805                         else
1806                         {
1807                                 /* later stack entries share the same storage */
1808                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1809                         }
1810                 }
1811                 else
1812                 {
1813                         /* recycle previously used EState */
1814                         epqstate = &(newepq->estate);
1815                 }
1816                 /* push current PQ to the stack */
1817                 epqstate->es_evalPlanQual = (Pointer) epq;
1818                 epq = newepq;
1819                 estate->es_evalPlanQual = (Pointer) epq;
1820                 epq->rti = rti;
1821                 endNode = false;
1822         }
1823
1824         Assert(epq->rti == rti);
1825         epqstate = &(epq->estate);
1826
1827         /*
1828          * Ok - we're requested for the same RTE.  Unfortunately we still
1829          * have to end and restart execution of the plan, because ExecReScan
1830          * wouldn't ensure that upper plan nodes would reset themselves.  We
1831          * could make that work if insertion of the target tuple were integrated
1832          * with the Param mechanism somehow, so that the upper plan nodes know
1833          * that their children's outputs have changed.
1834          */
1835         if (endNode)
1836         {
1837                 /* stop execution */
1838                 ExecEndNode(epq->plan, epq->plan);
1839                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1840                 epqstate->es_tupleTable = NULL;
1841         }
1842
1843         /*
1844          * free old RTE' tuple, if any, and store target tuple where relation's
1845          * scan node will see it
1846          */
1847         if (epqstate->es_evTuple[rti - 1] != NULL)
1848                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1849         epqstate->es_evTuple[rti - 1] = copyTuple;
1850
1851         /*
1852          * Initialize for new recheck query; be careful to copy down state
1853          * that might have changed in top EState.
1854          */
1855         epqstate->es_result_relation_info = estate->es_result_relation_info;
1856         epqstate->es_junkFilter = estate->es_junkFilter;
1857         if (estate->es_origPlan->nParamExec > 0)
1858                 memset(epqstate->es_param_exec_vals, 0,
1859                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1860         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1861         epqstate->es_useEvalPlan = false;
1862         Assert(epqstate->es_tupleTable == NULL);
1863         epqstate->es_tupleTable =
1864                 ExecCreateTupleTable(estate->es_tupleTable->size);
1865
1866         ExecInitNode(epq->plan, epqstate, NULL);
1867
1868         return EvalPlanQualNext(estate);
1869 }
1870
1871 static TupleTableSlot *
1872 EvalPlanQualNext(EState *estate)
1873 {
1874         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1875         EState     *epqstate = &(epq->estate);
1876         evalPlanQual *oldepq;
1877         TupleTableSlot *slot;
1878
1879         Assert(epq->rti != 0);
1880
1881 lpqnext:;
1882         slot = ExecProcNode(epq->plan, epq->plan);
1883
1884         /*
1885          * No more tuples for this PQ. Continue previous one.
1886          */
1887         if (TupIsNull(slot))
1888         {
1889                 /* stop execution */
1890                 ExecEndNode(epq->plan, epq->plan);
1891                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1892                 epqstate->es_tupleTable = NULL;
1893                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1894                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1895                 /* pop old PQ from the stack */
1896                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1897                 if (oldepq == (evalPlanQual *) NULL)
1898                 {
1899                         epq->rti = 0;           /* this is the first (oldest) */
1900                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1901                         return (NULL);          /* continue Query execution   */
1902                 }
1903                 Assert(oldepq->rti != 0);
1904                 /* push current PQ to freePQ stack */
1905                 oldepq->free = epq;
1906                 epq = oldepq;
1907                 epqstate = &(epq->estate);
1908                 estate->es_evalPlanQual = (Pointer) epq;
1909                 goto lpqnext;
1910         }
1911
1912         return (slot);
1913 }
1914
1915 static void
1916 EndEvalPlanQual(EState *estate)
1917 {
1918         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1919         EState     *epqstate = &(epq->estate);
1920         evalPlanQual *oldepq;
1921
1922         if (epq->rti == 0)                      /* plans already shutdowned */
1923         {
1924                 Assert(epq->estate.es_evalPlanQual == NULL);
1925                 return;
1926         }
1927
1928         for (;;)
1929         {
1930                 /* stop execution */
1931                 ExecEndNode(epq->plan, epq->plan);
1932                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1933                 epqstate->es_tupleTable = NULL;
1934                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1935                 {
1936                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1937                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1938                 }
1939                 /* pop old PQ from the stack */
1940                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1941                 if (oldepq == (evalPlanQual *) NULL)
1942                 {
1943                         epq->rti = 0;           /* this is the first (oldest) */
1944                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1945                         break;
1946                 }
1947                 Assert(oldepq->rti != 0);
1948                 /* push current PQ to freePQ stack */
1949                 oldepq->free = epq;
1950                 epq = oldepq;
1951                 epqstate = &(epq->estate);
1952                 estate->es_evalPlanQual = (Pointer) epq;
1953         }
1954 }