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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 direction 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) 1996-2002, 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 1.168 2002/06/26 21:58:56 momjian Exp $
  31  *
  32  *-------------------------------------------------------------------------
  33  */
  34 #include "postgres.h"
  35
  36 #include "access/heapam.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 "miscadmin.h"
  44 #include "optimizer/var.h"
  45 #include "parser/parsetree.h"
  46 #include "utils/acl.h"
  47 #include "utils/lsyscache.h"
  48
  49
  50 /* decls for local routines only used within this module */
  51 static TupleDesc InitPlan(CmdType operation,
  52                  Query *parseTree,
  53                  Plan *plan,
  54                  EState *estate);
  55 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  56                                   Index resultRelationIndex,
  57                                   List *rangeTable,
  58                                   CmdType operation);
  59 static void EndPlan(Plan *plan, EState *estate);
  60 static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan,
  61                         CmdType operation,
  62                         long numberTuples,
  63                         ScanDirection direction,
  64                         DestReceiver *destfunc);
  65 static void ExecSelect(TupleTableSlot *slot,
  66                          DestReceiver *destfunc,
  67                          EState *estate);
  68 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  69                    EState *estate);
  70 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  71                    EState *estate);
  72 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  73                         EState *estate);
  74 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  75 static void EndEvalPlanQual(EState *estate);
  76 static void ExecCheckQueryPerms(CmdType operation, Query *parseTree,
  77                                         Plan *plan);
  78 static void ExecCheckPlanPerms(Plan *plan, List *rangeTable,
  79                                    CmdType operation);
  80 static void ExecCheckRTPerms(List *rangeTable, CmdType operation);
  81 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  82
  83 /* end of local decls */
  84
  85
  86 /* ----------------------------------------------------------------
  87  *              ExecutorStart
  88  *
  89  *              This routine must be called at the beginning of any execution of any
  90  *              query plan
  91  *
  92  *              returns a TupleDesc which describes the attributes of the tuples to
  93  *              be returned by the query.  (Same value is saved in queryDesc)
  94  *
  95  * NB: the CurrentMemoryContext when this is called must be the context
  96  * to be used as the per-query context for the query plan.      ExecutorRun()
  97  * and ExecutorEnd() must be called in this same memory context.
  98  * ----------------------------------------------------------------
  99  */
 100 TupleDesc
 101 ExecutorStart(QueryDesc *queryDesc, EState *estate)
 102 {
 103         TupleDesc       result;
 104
 105         /* sanity checks */
 106         Assert(queryDesc != NULL);
 107
 108         if (queryDesc->plantree->nParamExec > 0)
 109         {
 110                 estate->es_param_exec_vals = (ParamExecData *)
 111                         palloc(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 112                 MemSet(estate->es_param_exec_vals, 0,
 113                            queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 114         }
 115
 116         /*
 117          * Make our own private copy of the current query snapshot data.
 118          *
 119          * This "freezes" our idea of which tuples are good and which are not
 120          * for the life of this query, even if it outlives the current command
 121          * and current snapshot.
 122          */
 123         estate->es_snapshot = CopyQuerySnapshot();
 124
 125         /*
 126          * Initialize the plan
 127          */
 128         result = InitPlan(queryDesc->operation,
 129                                           queryDesc->parsetree,
 130                                           queryDesc->plantree,
 131                                           estate);
 132
 133         queryDesc->tupDesc = result;
 134
 135         return result;
 136 }
 137
 138 /* ----------------------------------------------------------------
 139  *              ExecutorRun
 140  *
 141  *              This is the main routine of the executor module. It accepts
 142  *              the query descriptor from the traffic cop and executes the
 143  *              query plan.
 144  *
 145  *              ExecutorStart must have been called already.
 146  *
 147  *              If direction is NoMovementScanDirection then nothing is done
 148  *              except to start up/shut down the destination.  Otherwise,
 149  *              we retrieve up to 'count' tuples in the specified direction.
 150  *
 151  *              Note: count = 0 is interpreted as no portal limit, e.g. run to
 152  *              completion.
 153  *
 154  * ----------------------------------------------------------------
 155  */
 156 TupleTableSlot *
 157 ExecutorRun(QueryDesc *queryDesc, EState *estate,
 158                         ScanDirection direction, long count)
 159 {
 160         CmdType         operation;
 161         Plan       *plan;
 162         CommandDest dest;
 163         DestReceiver *destfunc;
 164         TupleTableSlot *result;
 165
 166         /*
 167          * sanity checks
 168          */
 169         Assert(queryDesc != NULL);
 170
 171         /*
 172          * extract information from the query descriptor and the query
 173          * feature.
 174          */
 175         operation = queryDesc->operation;
 176         plan = queryDesc->plantree;
 177         dest = queryDesc->dest;
 178
 179         /*
 180          * startup tuple receiver
 181          */
 182         estate->es_processed = 0;
 183         estate->es_lastoid = InvalidOid;
 184
 185         destfunc = DestToFunction(dest);
 186         (*destfunc->setup) (destfunc, (int) operation,
 187                                                 queryDesc->portalName, queryDesc->tupDesc);
 188
 189         /*
 190          * run plan
 191          */
 192         if (direction == NoMovementScanDirection)
 193                 result = NULL;
 194         else
 195                 result = ExecutePlan(estate,
 196                                                          plan,
 197                                                          operation,
 198                                                          count,
 199                                                          direction,
 200                                                          destfunc);
 201
 202         /*
 203          * shutdown receiver
 204          */
 205         (*destfunc->cleanup) (destfunc);
 206
 207         return result;
 208 }
 209
 210 /* ----------------------------------------------------------------
 211  *              ExecutorEnd
 212  *
 213  *              This routine must be called at the end of execution of any
 214  *              query plan
 215  * ----------------------------------------------------------------
 216  */
 217 void
 218 ExecutorEnd(QueryDesc *queryDesc, EState *estate)
 219 {
 220         /* sanity checks */
 221         Assert(queryDesc != NULL);
 222
 223         EndPlan(queryDesc->plantree, estate);
 224
 225         if (estate->es_snapshot != NULL)
 226         {
 227                 if (estate->es_snapshot->xcnt > 0)
 228                         pfree(estate->es_snapshot->xip);
 229                 pfree(estate->es_snapshot);
 230                 estate->es_snapshot = NULL;
 231         }
 232
 233         if (estate->es_param_exec_vals != NULL)
 234         {
 235                 pfree(estate->es_param_exec_vals);
 236                 estate->es_param_exec_vals = NULL;
 237         }
 238 }
 239
 240
 241 /*
 242  * ExecCheckQueryPerms
 243  *              Check access permissions for all relations referenced in a query.
 244  */
 245 static void
 246 ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan)
 247 {
 248         /*
 249          * Check RTEs in the query's primary rangetable.
 250          */
 251         ExecCheckRTPerms(parseTree->rtable, operation);
 252
 253         /*
 254          * Search for subplans and APPEND nodes to check their rangetables.
 255          */
 256         ExecCheckPlanPerms(plan, parseTree->rtable, operation);
 257 }
 258
 259 /*
 260  * ExecCheckPlanPerms
 261  *              Recursively scan the plan tree to check access permissions in
 262  *              subplans.
 263  */
 264 static void
 265 ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation)
 266 {
 267         List       *subp;
 268
 269         if (plan == NULL)
 270                 return;
 271
 272         /* Check subplans, which we assume are plain SELECT queries */
 273
 274         foreach(subp, plan->initPlan)
 275         {
 276                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 277
 278                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 279                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 280         }
 281         foreach(subp, plan->subPlan)
 282         {
 283                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 284
 285                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 286                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 287         }
 288
 289         /* Check lower plan nodes */
 290
 291         ExecCheckPlanPerms(plan->lefttree, rangeTable, operation);
 292         ExecCheckPlanPerms(plan->righttree, rangeTable, operation);
 293
 294         /* Do node-type-specific checks */
 295
 296         switch (nodeTag(plan))
 297         {
 298                 case T_SubqueryScan:
 299                         {
 300                                 SubqueryScan *scan = (SubqueryScan *) plan;
 301                                 RangeTblEntry *rte;
 302
 303                                 /* Recursively check the subquery */
 304                                 rte = rt_fetch(scan->scan.scanrelid, rangeTable);
 305                                 Assert(rte->rtekind == RTE_SUBQUERY);
 306                                 ExecCheckQueryPerms(operation, rte->subquery, scan->subplan);
 307                                 break;
 308                         }
 309                 case T_Append:
 310                         {
 311                                 Append     *app = (Append *) plan;
 312                                 List       *appendplans;
 313
 314                                 foreach(appendplans, app->appendplans)
 315                                 {
 316                                         ExecCheckPlanPerms((Plan *) lfirst(appendplans),
 317                                                                            rangeTable,
 318                                                                            operation);
 319                                 }
 320                                 break;
 321                         }
 322
 323                 default:
 324                         break;
 325         }
 326 }
 327
 328 /*
 329  * ExecCheckRTPerms
 330  *              Check access permissions for all relations listed in a range table.
 331  */
 332 static void
 333 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 334 {
 335         List       *lp;
 336
 337         foreach(lp, rangeTable)
 338         {
 339                 RangeTblEntry *rte = lfirst(lp);
 340
 341                 ExecCheckRTEPerms(rte, operation);
 342         }
 343 }
 344
 345 /*
 346  * ExecCheckRTEPerms
 347  *              Check access permissions for a single RTE.
 348  */
 349 static void
 350 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 351 {
 352         Oid                     relOid;
 353         Oid                     userid;
 354         AclResult       aclcheck_result;
 355
 356         /*
 357          * Only plain-relation RTEs need to be checked here.  Subquery RTEs
 358          * will be checked when ExecCheckPlanPerms finds the SubqueryScan node,
 359          * and function RTEs are checked by init_fcache when the function is
 360          * prepared for execution.  Join and special RTEs need no checks.
 361          */
 362         if (rte->rtekind != RTE_RELATION)
 363                 return;
 364
 365         relOid = rte->relid;
 366
 367         /*
 368          * userid to check as: current user unless we have a setuid
 369          * indication.
 370          *
 371          * Note: GetUserId() is presently fast enough that there's no harm in
 372          * calling it separately for each RTE.  If that stops being true, we
 373          * could call it once in ExecCheckQueryPerms and pass the userid down
 374          * from there.  But for now, no need for the extra clutter.
 375          */
 376         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 377
 378 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 379
 380         if (rte->checkForRead)
 381         {
 382                 aclcheck_result = CHECK(ACL_SELECT);
 383                 if (aclcheck_result != ACLCHECK_OK)
 384                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 385         }
 386
 387         if (rte->checkForWrite)
 388         {
 389                 /*
 390                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 391                  * Right now we don't distinguish that from true update as far as
 392                  * permissions checks are concerned.
 393                  */
 394                 switch (operation)
 395                 {
 396                         case CMD_INSERT:
 397                                 aclcheck_result = CHECK(ACL_INSERT);
 398                                 break;
 399                         case CMD_SELECT:
 400                         case CMD_UPDATE:
 401                                 aclcheck_result = CHECK(ACL_UPDATE);
 402                                 break;
 403                         case CMD_DELETE:
 404                                 aclcheck_result = CHECK(ACL_DELETE);
 405                                 break;
 406                         default:
 407                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 408                                          operation);
 409                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 410                                 break;
 411                 }
 412                 if (aclcheck_result != ACLCHECK_OK)
 413                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 414         }
 415 }
 416
 417
 418 /* ===============================================================
 419  * ===============================================================
 420                                                  static routines follow
 421  * ===============================================================
 422  * ===============================================================
 423  */
 424
 425 typedef struct execRowMark
 426 {
 427         Relation        relation;
 428         Index           rti;
 429         char            resname[32];
 430 } execRowMark;
 431
 432 typedef struct evalPlanQual
 433 {
 434         Plan       *plan;
 435         Index           rti;
 436         EState          estate;
 437         struct evalPlanQual *free;
 438 } evalPlanQual;
 439
 440 /* ----------------------------------------------------------------
 441  *              InitPlan
 442  *
 443  *              Initializes the query plan: open files, allocate storage
 444  *              and start up the rule manager
 445  * ----------------------------------------------------------------
 446  */
 447 static TupleDesc
 448 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 449 {
 450         List       *rangeTable;
 451         Relation        intoRelationDesc;
 452         TupleDesc       tupType;
 453
 454         /*
 455          * Do permissions checks.
 456          */
 457         ExecCheckQueryPerms(operation, parseTree, plan);
 458
 459         /*
 460          * get information from query descriptor
 461          */
 462         rangeTable = parseTree->rtable;
 463
 464         /*
 465          * initialize the node's execution state
 466          */
 467         estate->es_range_table = rangeTable;
 468
 469         /*
 470          * if there is a result relation, initialize result relation stuff
 471          */
 472         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 473         {
 474                 List       *resultRelations = parseTree->resultRelations;
 475                 int                     numResultRelations;
 476                 ResultRelInfo *resultRelInfos;
 477
 478                 if (resultRelations != NIL)
 479                 {
 480                         /*
 481                          * Multiple result relations (due to inheritance)
 482                          * parseTree->resultRelations identifies them all
 483                          */
 484                         ResultRelInfo *resultRelInfo;
 485
 486                         numResultRelations = length(resultRelations);
 487                         resultRelInfos = (ResultRelInfo *)
 488                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 489                         resultRelInfo = resultRelInfos;
 490                         while (resultRelations != NIL)
 491                         {
 492                                 initResultRelInfo(resultRelInfo,
 493                                                                   lfirsti(resultRelations),
 494                                                                   rangeTable,
 495                                                                   operation);
 496                                 resultRelInfo++;
 497                                 resultRelations = lnext(resultRelations);
 498                         }
 499                 }
 500                 else
 501                 {
 502                         /*
 503                          * Single result relation identified by
 504                          * parseTree->resultRelation
 505                          */
 506                         numResultRelations = 1;
 507                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 508                         initResultRelInfo(resultRelInfos,
 509                                                           parseTree->resultRelation,
 510                                                           rangeTable,
 511                                                           operation);
 512                 }
 513
 514                 estate->es_result_relations = resultRelInfos;
 515                 estate->es_num_result_relations = numResultRelations;
 516                 /* Initialize to first or only result rel */
 517                 estate->es_result_relation_info = resultRelInfos;
 518         }
 519         else
 520         {
 521                 /*
 522                  * if no result relation, then set state appropriately
 523                  */
 524                 estate->es_result_relations = NULL;
 525                 estate->es_num_result_relations = 0;
 526                 estate->es_result_relation_info = NULL;
 527         }
 528
 529         /*
 530          * Have to lock relations selected for update
 531          */
 532         estate->es_rowMark = NIL;
 533         if (parseTree->rowMarks != NIL)
 534         {
 535                 List       *l;
 536
 537                 foreach(l, parseTree->rowMarks)
 538                 {
 539                         Index           rti = lfirsti(l);
 540                         Oid                     relid = getrelid(rti, rangeTable);
 541                         Relation        relation;
 542                         execRowMark *erm;
 543
 544                         relation = heap_open(relid, RowShareLock);
 545                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 546                         erm->relation = relation;
 547                         erm->rti = rti;
 548                         sprintf(erm->resname, "ctid%u", rti);
 549                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 550                 }
 551         }
 552
 553         /*
 554          * initialize the executor "tuple" table.  We need slots for all the
 555          * plan nodes, plus possibly output slots for the junkfilter(s). At
 556          * this point we aren't sure if we need junkfilters, so just add slots
 557          * for them unconditionally.
 558          */
 559         {
 560                 int                     nSlots = ExecCountSlotsNode(plan);
 561
 562                 if (parseTree->resultRelations != NIL)
 563                         nSlots += length(parseTree->resultRelations);
 564                 else
 565                         nSlots += 1;
 566                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 567         }
 568
 569         /* mark EvalPlanQual not active */
 570         estate->es_origPlan = plan;
 571         estate->es_evalPlanQual = NULL;
 572         estate->es_evTuple = NULL;
 573         estate->es_evTupleNull = NULL;
 574         estate->es_useEvalPlan = false;
 575
 576         /*
 577          * initialize the private state information for all the nodes in the
 578          * query tree.  This opens files, allocates storage and leaves us
 579          * ready to start processing tuples.
 580          */
 581         ExecInitNode(plan, estate, NULL);
 582
 583         /*
 584          * Get the tuple descriptor describing the type of tuples to return.
 585          * (this is especially important if we are creating a relation with
 586          * "SELECT INTO")
 587          */
 588         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 589
 590         /*
 591          * Initialize the junk filter if needed. SELECT and INSERT queries
 592          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 593          * DELETE always need one, since there's always a junk 'ctid'
 594          * attribute present --- no need to look first.
 595          */
 596         {
 597                 bool            junk_filter_needed = false;
 598                 List       *tlist;
 599
 600                 switch (operation)
 601                 {
 602                         case CMD_SELECT:
 603                         case CMD_INSERT:
 604                                 foreach(tlist, plan->targetlist)
 605                                 {
 606                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 607
 608                                         if (tle->resdom->resjunk)
 609                                         {
 610                                                 junk_filter_needed = true;
 611                                                 break;
 612                                         }
 613                                 }
 614                                 break;
 615                         case CMD_UPDATE:
 616                         case CMD_DELETE:
 617                                 junk_filter_needed = true;
 618                                 break;
 619                         default:
 620                                 break;
 621                 }
 622
 623                 if (junk_filter_needed)
 624                 {
 625                         /*
 626                          * If there are multiple result relations, each one needs its
 627                          * own junk filter.  Note this is only possible for
 628                          * UPDATE/DELETE, so we can't be fooled by some needing a
 629                          * filter and some not.
 630                          */
 631                         if (parseTree->resultRelations != NIL)
 632                         {
 633                                 List       *subplans;
 634                                 ResultRelInfo *resultRelInfo;
 635
 636                                 /* Top plan had better be an Append here. */
 637                                 Assert(IsA(plan, Append));
 638                                 Assert(((Append *) plan)->isTarget);
 639                                 subplans = ((Append *) plan)->appendplans;
 640                                 Assert(length(subplans) == estate->es_num_result_relations);
 641                                 resultRelInfo = estate->es_result_relations;
 642                                 while (subplans != NIL)
 643                                 {
 644                                         Plan       *subplan = (Plan *) lfirst(subplans);
 645                                         JunkFilter *j;
 646
 647                                         j = ExecInitJunkFilter(subplan->targetlist,
 648                                                                                    ExecGetTupType(subplan),
 649                                                           ExecAllocTableSlot(estate->es_tupleTable));
 650                                         resultRelInfo->ri_junkFilter = j;
 651                                         resultRelInfo++;
 652                                         subplans = lnext(subplans);
 653                                 }
 654
 655                                 /*
 656                                  * Set active junkfilter too; at this point ExecInitAppend
 657                                  * has already selected an active result relation...
 658                                  */
 659                                 estate->es_junkFilter =
 660                                         estate->es_result_relation_info->ri_junkFilter;
 661                         }
 662                         else
 663                         {
 664                                 /* Normal case with just one JunkFilter */
 665                                 JunkFilter *j;
 666
 667                                 j = ExecInitJunkFilter(plan->targetlist,
 668                                                                            tupType,
 669                                                           ExecAllocTableSlot(estate->es_tupleTable));
 670                                 estate->es_junkFilter = j;
 671                                 if (estate->es_result_relation_info)
 672                                         estate->es_result_relation_info->ri_junkFilter = j;
 673
 674                                 /* For SELECT, want to return the cleaned tuple type */
 675                                 if (operation == CMD_SELECT)
 676                                         tupType = j->jf_cleanTupType;
 677                         }
 678                 }
 679                 else
 680                         estate->es_junkFilter = NULL;
 681         }
 682
 683         /*
 684          * initialize the "into" relation
 685          */
 686         intoRelationDesc = (Relation) NULL;
 687
 688         if (operation == CMD_SELECT)
 689         {
 690                 if (!parseTree->isPortal)
 691                 {
 692                         /*
 693                          * a select into table --- need to create the "into" table
 694                          */
 695                         if (parseTree->into != NULL)
 696                         {
 697                                 char       *intoName;
 698                                 Oid                     namespaceId;
 699                                 Oid                     intoRelationId;
 700                                 TupleDesc       tupdesc;
 701
 702                                 /*
 703                                  * find namespace to create in, check permissions
 704                                  */
 705                                 intoName = parseTree->into->relname;
 706                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 707
 708                                 if (!isTempNamespace(namespaceId))
 709                                 {
 710                                         AclResult       aclresult;
 711
 712                                         aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 713                                                                                                           ACL_CREATE);
 714                                         if (aclresult != ACLCHECK_OK)
 715                                                 aclcheck_error(aclresult,
 716                                                                            get_namespace_name(namespaceId));
 717                                 }
 718
 719                                 /*
 720                                  * have to copy tupType to get rid of constraints
 721                                  */
 722                                 tupdesc = CreateTupleDescCopy(tupType);
 723
 724                                 intoRelationId =
 725                                         heap_create_with_catalog(intoName,
 726                                                                                          namespaceId,
 727                                                                                          tupdesc,
 728                                                                                          RELKIND_RELATION,
 729                                                                                          false,
 730                                                                                          true,
 731                                                                                          allowSystemTableMods);
 732
 733                                 FreeTupleDesc(tupdesc);
 734
 735                                 /*
 736                                  * Advance command counter so that the newly-created
 737                                  * relation's catalog tuples will be visible to heap_open.
 738                                  */
 739                                 CommandCounterIncrement();
 740
 741                                 /*
 742                                  * If necessary, create a TOAST table for the into
 743                                  * relation. Note that AlterTableCreateToastTable ends
 744                                  * with CommandCounterIncrement(), so that the TOAST table
 745                                  * will be visible for insertion.
 746                                  */
 747                                 AlterTableCreateToastTable(intoRelationId, true);
 748
 749                                 intoRelationDesc = heap_open(intoRelationId,
 750                                                                                          AccessExclusiveLock);
 751                         }
 752                 }
 753         }
 754
 755         estate->es_into_relation_descriptor = intoRelationDesc;
 756
 757         return tupType;
 758 }
 759
 760 /*
 761  * Initialize ResultRelInfo data for one result relation
 762  */
 763 static void
 764 initResultRelInfo(ResultRelInfo *resultRelInfo,
 765                                   Index resultRelationIndex,
 766                                   List *rangeTable,
 767                                   CmdType operation)
 768 {
 769         Oid                     resultRelationOid;
 770         Relation        resultRelationDesc;
 771
 772         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 773         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 774
 775         switch (resultRelationDesc->rd_rel->relkind)
 776         {
 777                 case RELKIND_SEQUENCE:
 778                         elog(ERROR, "You can't change sequence relation %s",
 779                                  RelationGetRelationName(resultRelationDesc));
 780                         break;
 781                 case RELKIND_TOASTVALUE:
 782                         elog(ERROR, "You can't change toast relation %s",
 783                                  RelationGetRelationName(resultRelationDesc));
 784                         break;
 785                 case RELKIND_VIEW:
 786                         elog(ERROR, "You can't change view relation %s",
 787                                  RelationGetRelationName(resultRelationDesc));
 788                         break;
 789         }
 790
 791         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 792         resultRelInfo->type = T_ResultRelInfo;
 793         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 794         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 795         resultRelInfo->ri_NumIndices = 0;
 796         resultRelInfo->ri_IndexRelationDescs = NULL;
 797         resultRelInfo->ri_IndexRelationInfo = NULL;
 798         resultRelInfo->ri_TrigDesc = resultRelationDesc->trigdesc;
 799         resultRelInfo->ri_TrigFunctions = NULL;
 800         resultRelInfo->ri_ConstraintExprs = NULL;
 801         resultRelInfo->ri_junkFilter = NULL;
 802
 803         /*
 804          * If there are indices on the result relation, open them and save
 805          * descriptors in the result relation info, so that we can add new
 806          * index entries for the tuples we add/update.  We need not do this
 807          * for a DELETE, however, since deletion doesn't affect indexes.
 808          */
 809         if (resultRelationDesc->rd_rel->relhasindex &&
 810                 operation != CMD_DELETE)
 811                 ExecOpenIndices(resultRelInfo);
 812 }
 813
 814 /* ----------------------------------------------------------------
 815  *              EndPlan
 816  *
 817  *              Cleans up the query plan -- closes files and free up storages
 818  * ----------------------------------------------------------------
 819  */
 820 static void
 821 EndPlan(Plan *plan, EState *estate)
 822 {
 823         ResultRelInfo *resultRelInfo;
 824         int                     i;
 825         List       *l;
 826
 827         /*
 828          * shut down any PlanQual processing we were doing
 829          */
 830         if (estate->es_evalPlanQual != NULL)
 831                 EndEvalPlanQual(estate);
 832
 833         /*
 834          * shut down the node-type-specific query processing
 835          */
 836         ExecEndNode(plan, NULL);
 837
 838         /*
 839          * destroy the executor "tuple" table.
 840          */
 841         ExecDropTupleTable(estate->es_tupleTable, true);
 842         estate->es_tupleTable = NULL;
 843
 844         /*
 845          * close the result relation(s) if any, but hold locks until xact
 846          * commit.      Also clean up junkfilters if present.
 847          */
 848         resultRelInfo = estate->es_result_relations;
 849         for (i = estate->es_num_result_relations; i > 0; i--)
 850         {
 851                 /* Close indices and then the relation itself */
 852                 ExecCloseIndices(resultRelInfo);
 853                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 854                 /* Delete the junkfilter if any */
 855                 if (resultRelInfo->ri_junkFilter != NULL)
 856                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 857                 resultRelInfo++;
 858         }
 859
 860         /*
 861          * close the "into" relation if necessary, again keeping lock
 862          */
 863         if (estate->es_into_relation_descriptor != NULL)
 864                 heap_close(estate->es_into_relation_descriptor, NoLock);
 865
 866         /*
 867          * There might be a junkfilter without a result relation.
 868          */
 869         if (estate->es_num_result_relations == 0 &&
 870                 estate->es_junkFilter != NULL)
 871         {
 872                 ExecFreeJunkFilter(estate->es_junkFilter);
 873                 estate->es_junkFilter = NULL;
 874         }
 875
 876         /*
 877          * close any relations selected FOR UPDATE, again keeping locks
 878          */
 879         foreach(l, estate->es_rowMark)
 880         {
 881                 execRowMark *erm = lfirst(l);
 882
 883                 heap_close(erm->relation, NoLock);
 884         }
 885 }
 886
 887 /* ----------------------------------------------------------------
 888  *              ExecutePlan
 889  *
 890  *              processes the query plan to retrieve 'numberTuples' tuples in the
 891  *              direction specified.
 892  *              Retrieves all tuples if numberTuples is 0
 893  *
 894  *              result is either a slot containing the last tuple in the case
 895  *              of a SELECT or NULL otherwise.
 896  *
 897  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 898  * user can see it
 899  * ----------------------------------------------------------------
 900  */
 901 static TupleTableSlot *
 902 ExecutePlan(EState *estate,
 903                         Plan *plan,
 904                         CmdType operation,
 905                         long numberTuples,
 906                         ScanDirection direction,
 907                         DestReceiver *destfunc)
 908 {
 909         JunkFilter *junkfilter;
 910         TupleTableSlot *slot;
 911         ItemPointer tupleid = NULL;
 912         ItemPointerData tuple_ctid;
 913         long            current_tuple_count;
 914         TupleTableSlot *result;
 915
 916         /*
 917          * initialize local variables
 918          */
 919         slot = NULL;
 920         current_tuple_count = 0;
 921         result = NULL;
 922
 923         /*
 924          * Set the direction.
 925          */
 926         estate->es_direction = direction;
 927
 928         /*
 929          * Loop until we've processed the proper number of tuples from the
 930          * plan.
 931          */
 932
 933         for (;;)
 934         {
 935                 /* Reset the per-output-tuple exprcontext */
 936                 ResetPerTupleExprContext(estate);
 937
 938                 /*
 939                  * Execute the plan and obtain a tuple
 940                  */
 941 lnext:  ;
 942                 if (estate->es_useEvalPlan)
 943                 {
 944                         slot = EvalPlanQualNext(estate);
 945                         if (TupIsNull(slot))
 946                                 slot = ExecProcNode(plan, NULL);
 947                 }
 948                 else
 949                         slot = ExecProcNode(plan, NULL);
 950
 951                 /*
 952                  * if the tuple is null, then we assume there is nothing more to
 953                  * process so we just return null...
 954                  */
 955                 if (TupIsNull(slot))
 956                 {
 957                         result = NULL;
 958                         break;
 959                 }
 960
 961                 /*
 962                  * if we have a junk filter, then project a new tuple with the
 963                  * junk removed.
 964                  *
 965                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 966                  * (Formerly, we stored it back over the "dirty" tuple, which is
 967                  * WRONG because that tuple slot has the wrong descriptor.)
 968                  *
 969                  * Also, extract all the junk information we need.
 970                  */
 971                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 972                 {
 973                         Datum           datum;
 974                         HeapTuple       newTuple;
 975                         bool            isNull;
 976
 977                         /*
 978                          * extract the 'ctid' junk attribute.
 979                          */
 980                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 981                         {
 982                                 if (!ExecGetJunkAttribute(junkfilter,
 983                                                                                   slot,
 984                                                                                   "ctid",
 985                                                                                   &datum,
 986                                                                                   &isNull))
 987                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 988
 989                                 /* shouldn't ever get a null result... */
 990                                 if (isNull)
 991                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 992
 993                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 994                                 tuple_ctid = *tupleid;  /* make sure we don't free the
 995                                                                                  * ctid!! */
 996                                 tupleid = &tuple_ctid;
 997                         }
 998                         else if (estate->es_rowMark != NIL)
 999                         {
1000                                 List       *l;
1001
1002                 lmark:  ;
1003                                 foreach(l, estate->es_rowMark)
1004                                 {
1005                                         execRowMark *erm = lfirst(l);
1006                                         Buffer          buffer;
1007                                         HeapTupleData tuple;
1008                                         TupleTableSlot *newSlot;
1009                                         int                     test;
1010
1011                                         if (!ExecGetJunkAttribute(junkfilter,
1012                                                                                           slot,
1013                                                                                           erm->resname,
1014                                                                                           &datum,
1015                                                                                           &isNull))
1016                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1017                                                          erm->resname);
1018
1019                                         /* shouldn't ever get a null result... */
1020                                         if (isNull)
1021                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1022                                                          erm->resname);
1023
1024                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1025                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1026                                                                                         estate->es_snapshot->curcid);
1027                                         ReleaseBuffer(buffer);
1028                                         switch (test)
1029                                         {
1030                                                 case HeapTupleSelfUpdated:
1031                                                 case HeapTupleMayBeUpdated:
1032                                                         break;
1033
1034                                                 case HeapTupleUpdated:
1035                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1036                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1037                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1038                                                                   (ItemPointer) DatumGetPointer(datum))))
1039                                                         {
1040                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1041                                                                 if (!(TupIsNull(newSlot)))
1042                                                                 {
1043                                                                         slot = newSlot;
1044                                                                         estate->es_useEvalPlan = true;
1045                                                                         goto lmark;
1046                                                                 }
1047                                                         }
1048
1049                                                         /*
1050                                                          * if tuple was deleted or PlanQual failed for
1051                                                          * updated tuple - we must not return this
1052                                                          * tuple!
1053                                                          */
1054                                                         goto lnext;
1055
1056                                                 default:
1057                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1058                                                         return (NULL);
1059                                         }
1060                                 }
1061                         }
1062
1063                         /*
1064                          * Finally create a new "clean" tuple with all junk attributes
1065                          * removed
1066                          */
1067                         newTuple = ExecRemoveJunk(junkfilter, slot);
1068
1069                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1070                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1071                                                                   InvalidBuffer,        /* this tuple has no buffer */
1072                                                                   true);                /* tuple should be pfreed */
1073                 }
1074
1075                 /*
1076                  * now that we have a tuple, do the appropriate thing with it..
1077                  * either return it to the user, add it to a relation someplace,
1078                  * delete it from a relation, or modify some of its attributes.
1079                  */
1080                 switch (operation)
1081                 {
1082                         case CMD_SELECT:
1083                                 ExecSelect(slot,                /* slot containing tuple */
1084                                                    destfunc,    /* destination's tuple-receiver obj */
1085                                                    estate);
1086                                 result = slot;
1087                                 break;
1088
1089                         case CMD_INSERT:
1090                                 ExecInsert(slot, tupleid, estate);
1091                                 result = NULL;
1092                                 break;
1093
1094                         case CMD_DELETE:
1095                                 ExecDelete(slot, tupleid, estate);
1096                                 result = NULL;
1097                                 break;
1098
1099                         case CMD_UPDATE:
1100                                 ExecUpdate(slot, tupleid, estate);
1101                                 result = NULL;
1102                                 break;
1103
1104                         default:
1105                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1106                                 result = NULL;
1107                                 break;
1108                 }
1109
1110                 /*
1111                  * check our tuple count.. if we've processed the proper number
1112                  * then quit, else loop again and process more tuples..
1113                  */
1114                 current_tuple_count++;
1115                 if (numberTuples == current_tuple_count)
1116                         break;
1117         }
1118
1119         /*
1120          * here, result is either a slot containing a tuple in the case of a
1121          * SELECT or NULL otherwise.
1122          */
1123         return result;
1124 }
1125
1126 /* ----------------------------------------------------------------
1127  *              ExecSelect
1128  *
1129  *              SELECTs are easy.. we just pass the tuple to the appropriate
1130  *              print function.  The only complexity is when we do a
1131  *              "SELECT INTO", in which case we insert the tuple into
1132  *              the appropriate relation (note: this is a newly created relation
1133  *              so we don't need to worry about indices or locks.)
1134  * ----------------------------------------------------------------
1135  */
1136 static void
1137 ExecSelect(TupleTableSlot *slot,
1138                    DestReceiver *destfunc,
1139                    EState *estate)
1140 {
1141         HeapTuple       tuple;
1142         TupleDesc       attrtype;
1143
1144         /*
1145          * get the heap tuple out of the tuple table slot
1146          */
1147         tuple = slot->val;
1148         attrtype = slot->ttc_tupleDescriptor;
1149
1150         /*
1151          * insert the tuple into the "into relation"
1152          */
1153         if (estate->es_into_relation_descriptor != NULL)
1154         {
1155                 heap_insert(estate->es_into_relation_descriptor, tuple,
1156                                         estate->es_snapshot->curcid);
1157                 IncrAppended();
1158         }
1159
1160         /*
1161          * send the tuple to the front end (or the screen)
1162          */
1163         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1164         IncrRetrieved();
1165         (estate->es_processed)++;
1166 }
1167
1168 /* ----------------------------------------------------------------
1169  *              ExecInsert
1170  *
1171  *              INSERTs are trickier.. we have to insert the tuple into
1172  *              the base relation and insert appropriate tuples into the
1173  *              index relations.
1174  * ----------------------------------------------------------------
1175  */
1176 static void
1177 ExecInsert(TupleTableSlot *slot,
1178                    ItemPointer tupleid,
1179                    EState *estate)
1180 {
1181         HeapTuple       tuple;
1182         ResultRelInfo *resultRelInfo;
1183         Relation        resultRelationDesc;
1184         int                     numIndices;
1185         Oid                     newId;
1186
1187         /*
1188          * get the heap tuple out of the tuple table slot
1189          */
1190         tuple = slot->val;
1191
1192         /*
1193          * get information on the (current) result relation
1194          */
1195         resultRelInfo = estate->es_result_relation_info;
1196         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1197
1198         /* BEFORE ROW INSERT Triggers */
1199         if (resultRelInfo->ri_TrigDesc &&
1200           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1201         {
1202                 HeapTuple       newtuple;
1203
1204                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1205
1206                 if (newtuple == NULL)   /* "do nothing" */
1207                         return;
1208
1209                 if (newtuple != tuple)  /* modified by Trigger(s) */
1210                 {
1211                         /*
1212                          * Insert modified tuple into tuple table slot, replacing the
1213                          * original.  We assume that it was allocated in per-tuple
1214                          * memory context, and therefore will go away by itself. The
1215                          * tuple table slot should not try to clear it.
1216                          */
1217                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1218                         tuple = newtuple;
1219                 }
1220         }
1221
1222         /*
1223          * Check the constraints of the tuple
1224          */
1225         if (resultRelationDesc->rd_att->constr)
1226                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1227
1228         /*
1229          * insert the tuple
1230          */
1231         newId = heap_insert(resultRelationDesc, tuple,
1232                                                 estate->es_snapshot->curcid);
1233
1234         IncrAppended();
1235         (estate->es_processed)++;
1236         estate->es_lastoid = newId;
1237         setLastTid(&(tuple->t_self));
1238
1239         /*
1240          * process indices
1241          *
1242          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1243          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1244          * field.
1245          */
1246         numIndices = resultRelInfo->ri_NumIndices;
1247         if (numIndices > 0)
1248                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1249
1250         /* AFTER ROW INSERT Triggers */
1251         if (resultRelInfo->ri_TrigDesc)
1252                 ExecARInsertTriggers(estate, resultRelInfo, tuple);
1253 }
1254
1255 /* ----------------------------------------------------------------
1256  *              ExecDelete
1257  *
1258  *              DELETE is like UPDATE, we delete the tuple and its
1259  *              index tuples.
1260  * ----------------------------------------------------------------
1261  */
1262 static void
1263 ExecDelete(TupleTableSlot *slot,
1264                    ItemPointer tupleid,
1265                    EState *estate)
1266 {
1267         ResultRelInfo *resultRelInfo;
1268         Relation        resultRelationDesc;
1269         ItemPointerData ctid;
1270         int                     result;
1271
1272         /*
1273          * get information on the (current) result relation
1274          */
1275         resultRelInfo = estate->es_result_relation_info;
1276         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1277
1278         /* BEFORE ROW DELETE Triggers */
1279         if (resultRelInfo->ri_TrigDesc &&
1280           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1281         {
1282                 bool            dodelete;
1283
1284                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1285
1286                 if (!dodelete)                  /* "do nothing" */
1287                         return;
1288         }
1289
1290         /*
1291          * delete the tuple
1292          */
1293 ldelete:;
1294         result = heap_delete(resultRelationDesc, tupleid,
1295                                                  &ctid,
1296                                                  estate->es_snapshot->curcid);
1297         switch (result)
1298         {
1299                 case HeapTupleSelfUpdated:
1300                         return;
1301
1302                 case HeapTupleMayBeUpdated:
1303                         break;
1304
1305                 case HeapTupleUpdated:
1306                         if (XactIsoLevel == XACT_SERIALIZABLE)
1307                                 elog(ERROR, "Can't serialize access due to concurrent update");
1308                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1309                         {
1310                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1311                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1312
1313                                 if (!TupIsNull(epqslot))
1314                                 {
1315                                         *tupleid = ctid;
1316                                         goto ldelete;
1317                                 }
1318                         }
1319                         /* tuple already deleted; nothing to do */
1320                         return;
1321
1322                 default:
1323                         elog(ERROR, "Unknown status %u from heap_delete", result);
1324                         return;
1325         }
1326
1327         IncrDeleted();
1328         (estate->es_processed)++;
1329
1330         /*
1331          * Note: Normally one would think that we have to delete index tuples
1332          * associated with the heap tuple now..
1333          *
1334          * ... but in POSTGRES, we have no need to do this because the vacuum
1335          * daemon automatically opens an index scan and deletes index tuples
1336          * when it finds deleted heap tuples. -cim 9/27/89
1337          */
1338
1339         /* AFTER ROW DELETE Triggers */
1340         if (resultRelInfo->ri_TrigDesc)
1341                 ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1342 }
1343
1344 /* ----------------------------------------------------------------
1345  *              ExecUpdate
1346  *
1347  *              note: we can't run UPDATE queries with transactions
1348  *              off because UPDATEs are actually INSERTs and our
1349  *              scan will mistakenly loop forever, updating the tuple
1350  *              it just inserted..      This should be fixed but until it
1351  *              is, we don't want to get stuck in an infinite loop
1352  *              which corrupts your database..
1353  * ----------------------------------------------------------------
1354  */
1355 static void
1356 ExecUpdate(TupleTableSlot *slot,
1357                         ItemPointer tupleid,
1358                         EState *estate)
1359 {
1360         HeapTuple       tuple;
1361         ResultRelInfo *resultRelInfo;
1362         Relation        resultRelationDesc;
1363         ItemPointerData ctid;
1364         int                     result;
1365         int                     numIndices;
1366
1367         /*
1368          * abort the operation if not running transactions
1369          */
1370         if (IsBootstrapProcessingMode())
1371         {
1372                 elog(WARNING, "ExecReplace: replace can't run without transactions");
1373                 return;
1374         }
1375
1376         /*
1377          * get the heap tuple out of the tuple table slot
1378          */
1379         tuple = slot->val;
1380
1381         /*
1382          * get information on the (current) result relation
1383          */
1384         resultRelInfo = estate->es_result_relation_info;
1385         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1386
1387         /* BEFORE ROW UPDATE Triggers */
1388         if (resultRelInfo->ri_TrigDesc &&
1389           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1390         {
1391                 HeapTuple       newtuple;
1392
1393                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1394                                                                                 tupleid, tuple);
1395
1396                 if (newtuple == NULL)   /* "do nothing" */
1397                         return;
1398
1399                 if (newtuple != tuple)  /* modified by Trigger(s) */
1400                 {
1401                         /*
1402                          * Insert modified tuple into tuple table slot, replacing the
1403                          * original.  We assume that it was allocated in per-tuple
1404                          * memory context, and therefore will go away by itself. The
1405                          * tuple table slot should not try to clear it.
1406                          */
1407                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1408                         tuple = newtuple;
1409                 }
1410         }
1411
1412         /*
1413          * Check the constraints of the tuple
1414          *
1415          * If we generate a new candidate tuple after EvalPlanQual testing, we
1416          * must loop back here and recheck constraints.  (We don't need to
1417          * redo triggers, however.      If there are any BEFORE triggers then
1418          * trigger.c will have done mark4update to lock the correct tuple, so
1419          * there's no need to do them again.)
1420          */
1421 lreplace:;
1422         if (resultRelationDesc->rd_att->constr)
1423                 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1424
1425         /*
1426          * replace the heap tuple
1427          */
1428         result = heap_update(resultRelationDesc, tupleid, tuple,
1429                                                  &ctid,
1430                                                  estate->es_snapshot->curcid);
1431         switch (result)
1432         {
1433                 case HeapTupleSelfUpdated:
1434                         return;
1435
1436                 case HeapTupleMayBeUpdated:
1437                         break;
1438
1439                 case HeapTupleUpdated:
1440                         if (XactIsoLevel == XACT_SERIALIZABLE)
1441                                 elog(ERROR, "Can't serialize access due to concurrent update");
1442                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1443                         {
1444                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1445                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1446
1447                                 if (!TupIsNull(epqslot))
1448                                 {
1449                                         *tupleid = ctid;
1450                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1451                                         slot = ExecStoreTuple(tuple,
1452                                                                         estate->es_junkFilter->jf_resultSlot,
1453                                                                                   InvalidBuffer, true);
1454                                         goto lreplace;
1455                                 }
1456                         }
1457                         /* tuple already deleted; nothing to do */
1458                         return;
1459
1460                 default:
1461                         elog(ERROR, "Unknown status %u from heap_update", result);
1462                         return;
1463         }
1464
1465         IncrReplaced();
1466         (estate->es_processed)++;
1467
1468         /*
1469          * Note: instead of having to update the old index tuples associated
1470          * with the heap tuple, all we do is form and insert new index tuples.
1471          * This is because UPDATEs are actually DELETEs and INSERTs and index
1472          * tuple deletion is done automagically by the vacuum daemon. All we
1473          * do is insert new index tuples.  -cim 9/27/89
1474          */
1475
1476         /*
1477          * process indices
1478          *
1479          * heap_update updates a tuple in the base relation by invalidating it
1480          * and then inserting a new tuple to the relation.      As a side effect,
1481          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1482          * field.  So we now insert index tuples using the new tupleid stored
1483          * there.
1484          */
1485
1486         numIndices = resultRelInfo->ri_NumIndices;
1487         if (numIndices > 0)
1488                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1489
1490         /* AFTER ROW UPDATE Triggers */
1491         if (resultRelInfo->ri_TrigDesc)
1492                 ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1493 }
1494
1495 static char *
1496 ExecRelCheck(ResultRelInfo *resultRelInfo,
1497                          TupleTableSlot *slot, EState *estate)
1498 {
1499         Relation        rel = resultRelInfo->ri_RelationDesc;
1500         int                     ncheck = rel->rd_att->constr->num_check;
1501         ConstrCheck *check = rel->rd_att->constr->check;
1502         ExprContext *econtext;
1503         MemoryContext oldContext;
1504         List       *qual;
1505         int                     i;
1506
1507         /*
1508          * If first time through for this result relation, build expression
1509          * nodetrees for rel's constraint expressions.  Keep them in the
1510          * per-query memory context so they'll survive throughout the query.
1511          */
1512         if (resultRelInfo->ri_ConstraintExprs == NULL)
1513         {
1514                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1515                 resultRelInfo->ri_ConstraintExprs =
1516                         (List **) palloc(ncheck * sizeof(List *));
1517                 for (i = 0; i < ncheck; i++)
1518                 {
1519                         qual = (List *) stringToNode(check[i].ccbin);
1520                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1521                 }
1522                 MemoryContextSwitchTo(oldContext);
1523         }
1524
1525         /*
1526          * We will use the EState's per-tuple context for evaluating
1527          * constraint expressions (creating it if it's not already there).
1528          */
1529         econtext = GetPerTupleExprContext(estate);
1530
1531         /* Arrange for econtext's scan tuple to be the tuple under test */
1532         econtext->ecxt_scantuple = slot;
1533
1534         /* And evaluate the constraints */
1535         for (i = 0; i < ncheck; i++)
1536         {
1537                 qual = resultRelInfo->ri_ConstraintExprs[i];
1538
1539                 /*
1540                  * NOTE: SQL92 specifies that a NULL result from a constraint
1541                  * expression is not to be treated as a failure.  Therefore, tell
1542                  * ExecQual to return TRUE for NULL.
1543                  */
1544                 if (!ExecQual(qual, econtext, true))
1545                         return check[i].ccname;
1546         }
1547
1548         /* NULL result means no error */
1549         return (char *) NULL;
1550 }
1551
1552 void
1553 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1554                                 TupleTableSlot *slot, EState *estate)
1555 {
1556         Relation        rel = resultRelInfo->ri_RelationDesc;
1557         HeapTuple       tuple = slot->val;
1558         TupleConstr *constr = rel->rd_att->constr;
1559
1560         Assert(constr);
1561
1562         if (constr->has_not_null)
1563         {
1564                 int                     natts = rel->rd_att->natts;
1565                 int                     attrChk;
1566
1567                 for (attrChk = 1; attrChk <= natts; attrChk++)
1568                 {
1569                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1570                                 heap_attisnull(tuple, attrChk))
1571                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1572                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1573                 }
1574         }
1575
1576         if (constr->num_check > 0)
1577         {
1578                 char       *failed;
1579
1580                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1581                         elog(ERROR, "%s: rejected due to CHECK constraint %s",
1582                                  caller, failed);
1583         }
1584 }
1585
1586 /*
1587  * Check a modified tuple to see if we want to process its updated version
1588  * under READ COMMITTED rules.
1589  *
1590  * See backend/executor/README for some info about how this works.
1591  */
1592 TupleTableSlot *
1593 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1594 {
1595         evalPlanQual *epq;
1596         EState     *epqstate;
1597         Relation        relation;
1598         HeapTupleData tuple;
1599         HeapTuple       copyTuple = NULL;
1600         int                     rtsize;
1601         bool            endNode;
1602
1603         Assert(rti != 0);
1604
1605         /*
1606          * find relation containing target tuple
1607          */
1608         if (estate->es_result_relation_info != NULL &&
1609                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1610                 relation = estate->es_result_relation_info->ri_RelationDesc;
1611         else
1612         {
1613                 List       *l;
1614
1615                 relation = NULL;
1616                 foreach(l, estate->es_rowMark)
1617                 {
1618                         if (((execRowMark *) lfirst(l))->rti == rti)
1619                         {
1620                                 relation = ((execRowMark *) lfirst(l))->relation;
1621                                 break;
1622                         }
1623                 }
1624                 if (relation == NULL)
1625                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1626         }
1627
1628         /*
1629          * fetch tid tuple
1630          *
1631          * Loop here to deal with updated or busy tuples
1632          */
1633         tuple.t_self = *tid;
1634         for (;;)
1635         {
1636                 Buffer          buffer;
1637
1638                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1639                 {
1640                         TransactionId xwait = SnapshotDirty->xmax;
1641
1642                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1643                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1644
1645                         /*
1646                          * If tuple is being updated by other transaction then we have
1647                          * to wait for its commit/abort.
1648                          */
1649                         if (TransactionIdIsValid(xwait))
1650                         {
1651                                 ReleaseBuffer(buffer);
1652                                 XactLockTableWait(xwait);
1653                                 continue;
1654                         }
1655
1656                         /*
1657                          * We got tuple - now copy it for use by recheck query.
1658                          */
1659                         copyTuple = heap_copytuple(&tuple);
1660                         ReleaseBuffer(buffer);
1661                         break;
1662                 }
1663
1664                 /*
1665                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1666                  * Note that it's possible to get invalid SnapshotDirty->tid if
1667                  * tuple updated by this transaction. Have we to check this ?
1668                  */
1669                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1670                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1671                 {
1672                         /* updated, so look at the updated copy */
1673                         tuple.t_self = SnapshotDirty->tid;
1674                         continue;
1675                 }
1676
1677                 /*
1678                  * Deleted or updated by this transaction; forget it.
1679                  */
1680                 return NULL;
1681         }
1682
1683         /*
1684          * For UPDATE/DELETE we have to return tid of actual row we're
1685          * executing PQ for.
1686          */
1687         *tid = tuple.t_self;
1688
1689         /*
1690          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1691          */
1692         epq = (evalPlanQual *) estate->es_evalPlanQual;
1693         rtsize = length(estate->es_range_table);
1694         endNode = true;
1695
1696         if (epq != NULL && epq->rti == 0)
1697         {
1698                 /* Top PQ stack entry is idle, so re-use it */
1699                 Assert(!(estate->es_useEvalPlan) &&
1700                            epq->estate.es_evalPlanQual == NULL);
1701                 epq->rti = rti;
1702                 endNode = false;
1703         }
1704
1705         /*
1706          * If this is request for another RTE - Ra, - then we have to check
1707          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1708          * updated again and we have to re-start old execution for Ra and
1709          * forget all what we done after Ra was suspended. Cool? -:))
1710          */
1711         if (epq != NULL && epq->rti != rti &&
1712                 epq->estate.es_evTuple[rti - 1] != NULL)
1713         {
1714                 do
1715                 {
1716                         evalPlanQual *oldepq;
1717
1718                         /* pop previous PlanQual from the stack */
1719                         epqstate = &(epq->estate);
1720                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1721                         Assert(oldepq->rti != 0);
1722                         /* stop execution */
1723                         ExecEndNode(epq->plan, NULL);
1724                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1725                         epqstate->es_tupleTable = NULL;
1726                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1727                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1728                         /* push current PQ to freePQ stack */
1729                         oldepq->free = epq;
1730                         epq = oldepq;
1731                         estate->es_evalPlanQual = (Pointer) epq;
1732                 } while (epq->rti != rti);
1733         }
1734
1735         /*
1736          * If we are requested for another RTE then we have to suspend
1737          * execution of current PlanQual and start execution for new one.
1738          */
1739         if (epq == NULL || epq->rti != rti)
1740         {
1741                 /* try to reuse plan used previously */
1742                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1743
1744                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1745                 {
1746                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1747                         newepq->free = NULL;
1748
1749                         /*
1750                          * Each stack level has its own copy of the plan tree.  This
1751                          * is wasteful, but necessary as long as plan nodes point to
1752                          * exec state nodes rather than vice versa.  Note that
1753                          * copyfuncs.c doesn't attempt to copy the exec state nodes,
1754                          * which is a good thing in this situation.
1755                          */
1756                         newepq->plan = copyObject(estate->es_origPlan);
1757
1758                         /*
1759                          * Init stack level's EState.  We share top level's copy of
1760                          * es_result_relations array and other non-changing status. We
1761                          * need our own tupletable, es_param_exec_vals, and other
1762                          * changeable state.
1763                          */
1764                         epqstate = &(newepq->estate);
1765                         memcpy(epqstate, estate, sizeof(EState));
1766                         epqstate->es_direction = ForwardScanDirection;
1767                         if (estate->es_origPlan->nParamExec > 0)
1768                                 epqstate->es_param_exec_vals = (ParamExecData *)
1769                                         palloc(estate->es_origPlan->nParamExec *
1770                                                    sizeof(ParamExecData));
1771                         epqstate->es_tupleTable = NULL;
1772                         epqstate->es_per_tuple_exprcontext = NULL;
1773
1774                         /*
1775                          * Each epqstate must have its own es_evTupleNull state, but
1776                          * all the stack entries share es_evTuple state.  This allows
1777                          * sub-rechecks to inherit the value being examined by an
1778                          * outer recheck.
1779                          */
1780                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1781                         if (epq == NULL)
1782                         {
1783                                 /* first PQ stack entry */
1784                                 epqstate->es_evTuple = (HeapTuple *)
1785                                         palloc(rtsize * sizeof(HeapTuple));
1786                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1787                         }
1788                         else
1789                         {
1790                                 /* later stack entries share the same storage */
1791                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1792                         }
1793                 }
1794                 else
1795                 {
1796                         /* recycle previously used EState */
1797                         epqstate = &(newepq->estate);
1798                 }
1799                 /* push current PQ to the stack */
1800                 epqstate->es_evalPlanQual = (Pointer) epq;
1801                 epq = newepq;
1802                 estate->es_evalPlanQual = (Pointer) epq;
1803                 epq->rti = rti;
1804                 endNode = false;
1805         }
1806
1807         Assert(epq->rti == rti);
1808         epqstate = &(epq->estate);
1809
1810         /*
1811          * Ok - we're requested for the same RTE.  Unfortunately we still have
1812          * to end and restart execution of the plan, because ExecReScan
1813          * wouldn't ensure that upper plan nodes would reset themselves.  We
1814          * could make that work if insertion of the target tuple were
1815          * integrated with the Param mechanism somehow, so that the upper plan
1816          * nodes know that their children's outputs have changed.
1817          */
1818         if (endNode)
1819         {
1820                 /* stop execution */
1821                 ExecEndNode(epq->plan, NULL);
1822                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1823                 epqstate->es_tupleTable = NULL;
1824         }
1825
1826         /*
1827          * free old RTE' tuple, if any, and store target tuple where
1828          * relation's scan node will see it
1829          */
1830         if (epqstate->es_evTuple[rti - 1] != NULL)
1831                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1832         epqstate->es_evTuple[rti - 1] = copyTuple;
1833
1834         /*
1835          * Initialize for new recheck query; be careful to copy down state
1836          * that might have changed in top EState.
1837          */
1838         epqstate->es_result_relation_info = estate->es_result_relation_info;
1839         epqstate->es_junkFilter = estate->es_junkFilter;
1840         if (estate->es_origPlan->nParamExec > 0)
1841                 memset(epqstate->es_param_exec_vals, 0,
1842                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1843         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1844         epqstate->es_useEvalPlan = false;
1845         Assert(epqstate->es_tupleTable == NULL);
1846         epqstate->es_tupleTable =
1847                 ExecCreateTupleTable(estate->es_tupleTable->size);
1848
1849         ExecInitNode(epq->plan, epqstate, NULL);
1850
1851         return EvalPlanQualNext(estate);
1852 }
1853
1854 static TupleTableSlot *
1855 EvalPlanQualNext(EState *estate)
1856 {
1857         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1858         EState     *epqstate = &(epq->estate);
1859         evalPlanQual *oldepq;
1860         TupleTableSlot *slot;
1861
1862         Assert(epq->rti != 0);
1863
1864 lpqnext:;
1865         slot = ExecProcNode(epq->plan, NULL);
1866
1867         /*
1868          * No more tuples for this PQ. Continue previous one.
1869          */
1870         if (TupIsNull(slot))
1871         {
1872                 /* stop execution */
1873                 ExecEndNode(epq->plan, NULL);
1874                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1875                 epqstate->es_tupleTable = NULL;
1876                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1877                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1878                 /* pop old PQ from the stack */
1879                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1880                 if (oldepq == (evalPlanQual *) NULL)
1881                 {
1882                         epq->rti = 0;           /* this is the first (oldest) */
1883                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1884                         return (NULL);          /* continue Query execution   */
1885                 }
1886                 Assert(oldepq->rti != 0);
1887                 /* push current PQ to freePQ stack */
1888                 oldepq->free = epq;
1889                 epq = oldepq;
1890                 epqstate = &(epq->estate);
1891                 estate->es_evalPlanQual = (Pointer) epq;
1892                 goto lpqnext;
1893         }
1894
1895         return (slot);
1896 }
1897
1898 static void
1899 EndEvalPlanQual(EState *estate)
1900 {
1901         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1902         EState     *epqstate = &(epq->estate);
1903         evalPlanQual *oldepq;
1904
1905         if (epq->rti == 0)                      /* plans already shutdowned */
1906         {
1907                 Assert(epq->estate.es_evalPlanQual == NULL);
1908                 return;
1909         }
1910
1911         for (;;)
1912         {
1913                 /* stop execution */
1914                 ExecEndNode(epq->plan, NULL);
1915                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1916                 epqstate->es_tupleTable = NULL;
1917                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1918                 {
1919                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1920                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1921                 }
1922                 /* pop old PQ from the stack */
1923                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1924                 if (oldepq == (evalPlanQual *) NULL)
1925                 {
1926                         epq->rti = 0;           /* this is the first (oldest) */
1927                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1928                         break;
1929                 }
1930                 Assert(oldepq->rti != 0);
1931                 /* push current PQ to freePQ stack */
1932                 oldepq->free = epq;
1933                 epq = oldepq;
1934                 epqstate = &(epq->estate);
1935                 estate->es_evalPlanQual = (Pointer) epq;
1936         }
1937 }