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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.165 2002/06/20 20:29:27 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 ExecRetrieve(TupleTableSlot *slot,
  66                          DestReceiver *destfunc,
  67                          EState *estate);
  68 static void ExecAppend(TupleTableSlot *slot, ItemPointer tupleid,
  69                    EState *estate);
  70 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  71                    EState *estate);
  72 static void ExecReplace(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          * "retrieve 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 RETRIEVE 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
1072                                                                                                                  * buffer */
1073                                                                   true);                /* tuple should be pfreed */
1074                 }                                               /* if (junkfilter... */
1075
1076                 /*
1077                  * now that we have a tuple, do the appropriate thing with it..
1078                  * either return it to the user, add it to a relation someplace,
1079                  * delete it from a relation, or modify some of its attributes.
1080                  */
1081
1082                 switch (operation)
1083                 {
1084                         case CMD_SELECT:
1085                                 ExecRetrieve(slot,              /* slot containing tuple */
1086                                                          destfunc,      /* destination's tuple-receiver
1087                                                                                  * obj */
1088                                                          estate);       /* */
1089                                 result = slot;
1090                                 break;
1091
1092                         case CMD_INSERT:
1093                                 ExecAppend(slot, tupleid, estate);
1094                                 result = NULL;
1095                                 break;
1096
1097                         case CMD_DELETE:
1098                                 ExecDelete(slot, tupleid, estate);
1099                                 result = NULL;
1100                                 break;
1101
1102                         case CMD_UPDATE:
1103                                 ExecReplace(slot, tupleid, estate);
1104                                 result = NULL;
1105                                 break;
1106
1107                         default:
1108                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1109                                 result = NULL;
1110                                 break;
1111                 }
1112
1113                 /*
1114                  * check our tuple count.. if we've processed the proper number
1115                  * then quit, else loop again and process more tuples..
1116                  */
1117                 current_tuple_count++;
1118                 if (numberTuples == current_tuple_count)
1119                         break;
1120         }
1121
1122         /*
1123          * here, result is either a slot containing a tuple in the case of a
1124          * RETRIEVE or NULL otherwise.
1125          */
1126         return result;
1127 }
1128
1129 /* ----------------------------------------------------------------
1130  *              ExecRetrieve
1131  *
1132  *              RETRIEVEs are easy.. we just pass the tuple to the appropriate
1133  *              print function.  The only complexity is when we do a
1134  *              "retrieve into", in which case we insert the tuple into
1135  *              the appropriate relation (note: this is a newly created relation
1136  *              so we don't need to worry about indices or locks.)
1137  * ----------------------------------------------------------------
1138  */
1139 static void
1140 ExecRetrieve(TupleTableSlot *slot,
1141                          DestReceiver *destfunc,
1142                          EState *estate)
1143 {
1144         HeapTuple       tuple;
1145         TupleDesc       attrtype;
1146
1147         /*
1148          * get the heap tuple out of the tuple table slot
1149          */
1150         tuple = slot->val;
1151         attrtype = slot->ttc_tupleDescriptor;
1152
1153         /*
1154          * insert the tuple into the "into relation"
1155          */
1156         if (estate->es_into_relation_descriptor != NULL)
1157         {
1158                 heap_insert(estate->es_into_relation_descriptor, tuple,
1159                                         estate->es_snapshot->curcid);
1160                 IncrAppended();
1161         }
1162
1163         /*
1164          * send the tuple to the front end (or the screen)
1165          */
1166         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1167         IncrRetrieved();
1168         (estate->es_processed)++;
1169 }
1170
1171 /* ----------------------------------------------------------------
1172  *              ExecAppend
1173  *
1174  *              APPENDs are trickier.. we have to insert the tuple into
1175  *              the base relation and insert appropriate tuples into the
1176  *              index relations.
1177  * ----------------------------------------------------------------
1178  */
1179
1180 static void
1181 ExecAppend(TupleTableSlot *slot,
1182                    ItemPointer tupleid,
1183                    EState *estate)
1184 {
1185         HeapTuple       tuple;
1186         ResultRelInfo *resultRelInfo;
1187         Relation        resultRelationDesc;
1188         int                     numIndices;
1189         Oid                     newId;
1190
1191         /*
1192          * get the heap tuple out of the tuple table slot
1193          */
1194         tuple = slot->val;
1195
1196         /*
1197          * get information on the (current) result relation
1198          */
1199         resultRelInfo = estate->es_result_relation_info;
1200         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1201
1202         /* BEFORE ROW INSERT Triggers */
1203         if (resultRelInfo->ri_TrigDesc &&
1204           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1205         {
1206                 HeapTuple       newtuple;
1207
1208                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1209
1210                 if (newtuple == NULL)   /* "do nothing" */
1211                         return;
1212
1213                 if (newtuple != tuple)  /* modified by Trigger(s) */
1214                 {
1215                         /*
1216                          * Insert modified tuple into tuple table slot, replacing the
1217                          * original.  We assume that it was allocated in per-tuple
1218                          * memory context, and therefore will go away by itself. The
1219                          * tuple table slot should not try to clear it.
1220                          */
1221                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1222                         tuple = newtuple;
1223                 }
1224         }
1225
1226         /*
1227          * Check the constraints of the tuple
1228          */
1229         if (resultRelationDesc->rd_att->constr)
1230                 ExecConstraints("ExecAppend", resultRelInfo, slot, estate);
1231
1232         /*
1233          * insert the tuple
1234          */
1235         newId = heap_insert(resultRelationDesc, tuple,
1236                                                 estate->es_snapshot->curcid);
1237
1238         IncrAppended();
1239         (estate->es_processed)++;
1240         estate->es_lastoid = newId;
1241         setLastTid(&(tuple->t_self));
1242
1243         /*
1244          * process indices
1245          *
1246          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1247          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1248          * field.
1249          */
1250         numIndices = resultRelInfo->ri_NumIndices;
1251         if (numIndices > 0)
1252                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1253
1254         /* AFTER ROW INSERT Triggers */
1255         if (resultRelInfo->ri_TrigDesc)
1256                 ExecARInsertTriggers(estate, resultRelInfo, tuple);
1257 }
1258
1259 /* ----------------------------------------------------------------
1260  *              ExecDelete
1261  *
1262  *              DELETE is like append, we delete the tuple and its
1263  *              index tuples.
1264  * ----------------------------------------------------------------
1265  */
1266 static void
1267 ExecDelete(TupleTableSlot *slot,
1268                    ItemPointer tupleid,
1269                    EState *estate)
1270 {
1271         ResultRelInfo *resultRelInfo;
1272         Relation        resultRelationDesc;
1273         ItemPointerData ctid;
1274         int                     result;
1275
1276         /*
1277          * get information on the (current) result relation
1278          */
1279         resultRelInfo = estate->es_result_relation_info;
1280         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1281
1282         /* BEFORE ROW DELETE Triggers */
1283         if (resultRelInfo->ri_TrigDesc &&
1284           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1285         {
1286                 bool            dodelete;
1287
1288                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1289
1290                 if (!dodelete)                  /* "do nothing" */
1291                         return;
1292         }
1293
1294         /*
1295          * delete the tuple
1296          */
1297 ldelete:;
1298         result = heap_delete(resultRelationDesc, tupleid,
1299                                                  &ctid,
1300                                                  estate->es_snapshot->curcid);
1301         switch (result)
1302         {
1303                 case HeapTupleSelfUpdated:
1304                         return;
1305
1306                 case HeapTupleMayBeUpdated:
1307                         break;
1308
1309                 case HeapTupleUpdated:
1310                         if (XactIsoLevel == XACT_SERIALIZABLE)
1311                                 elog(ERROR, "Can't serialize access due to concurrent update");
1312                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1313                         {
1314                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1315                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1316
1317                                 if (!TupIsNull(epqslot))
1318                                 {
1319                                         *tupleid = ctid;
1320                                         goto ldelete;
1321                                 }
1322                         }
1323                         /* tuple already deleted; nothing to do */
1324                         return;
1325
1326                 default:
1327                         elog(ERROR, "Unknown status %u from heap_delete", result);
1328                         return;
1329         }
1330
1331         IncrDeleted();
1332         (estate->es_processed)++;
1333
1334         /*
1335          * Note: Normally one would think that we have to delete index tuples
1336          * associated with the heap tuple now..
1337          *
1338          * ... but in POSTGRES, we have no need to do this because the vacuum
1339          * daemon automatically opens an index scan and deletes index tuples
1340          * when it finds deleted heap tuples. -cim 9/27/89
1341          */
1342
1343         /* AFTER ROW DELETE Triggers */
1344         if (resultRelInfo->ri_TrigDesc)
1345                 ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1346 }
1347
1348 /* ----------------------------------------------------------------
1349  *              ExecReplace
1350  *
1351  *              note: we can't run replace queries with transactions
1352  *              off because replaces are actually appends and our
1353  *              scan will mistakenly loop forever, replacing the tuple
1354  *              it just appended..      This should be fixed but until it
1355  *              is, we don't want to get stuck in an infinite loop
1356  *              which corrupts your database..
1357  * ----------------------------------------------------------------
1358  */
1359 static void
1360 ExecReplace(TupleTableSlot *slot,
1361                         ItemPointer tupleid,
1362                         EState *estate)
1363 {
1364         HeapTuple       tuple;
1365         ResultRelInfo *resultRelInfo;
1366         Relation        resultRelationDesc;
1367         ItemPointerData ctid;
1368         int                     result;
1369         int                     numIndices;
1370
1371         /*
1372          * abort the operation if not running transactions
1373          */
1374         if (IsBootstrapProcessingMode())
1375         {
1376                 elog(WARNING, "ExecReplace: replace can't run without transactions");
1377                 return;
1378         }
1379
1380         /*
1381          * get the heap tuple out of the tuple table slot
1382          */
1383         tuple = slot->val;
1384
1385         /*
1386          * get information on the (current) result relation
1387          */
1388         resultRelInfo = estate->es_result_relation_info;
1389         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1390
1391         /* BEFORE ROW UPDATE Triggers */
1392         if (resultRelInfo->ri_TrigDesc &&
1393           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1394         {
1395                 HeapTuple       newtuple;
1396
1397                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1398                                                                                 tupleid, tuple);
1399
1400                 if (newtuple == NULL)   /* "do nothing" */
1401                         return;
1402
1403                 if (newtuple != tuple)  /* modified by Trigger(s) */
1404                 {
1405                         /*
1406                          * Insert modified tuple into tuple table slot, replacing the
1407                          * original.  We assume that it was allocated in per-tuple
1408                          * memory context, and therefore will go away by itself. The
1409                          * tuple table slot should not try to clear it.
1410                          */
1411                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1412                         tuple = newtuple;
1413                 }
1414         }
1415
1416         /*
1417          * Check the constraints of the tuple
1418          *
1419          * If we generate a new candidate tuple after EvalPlanQual testing, we
1420          * must loop back here and recheck constraints.  (We don't need to
1421          * redo triggers, however.      If there are any BEFORE triggers then
1422          * trigger.c will have done mark4update to lock the correct tuple, so
1423          * there's no need to do them again.)
1424          */
1425 lreplace:;
1426         if (resultRelationDesc->rd_att->constr)
1427                 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1428
1429         /*
1430          * replace the heap tuple
1431          */
1432         result = heap_update(resultRelationDesc, tupleid, tuple,
1433                                                  &ctid,
1434                                                  estate->es_snapshot->curcid);
1435         switch (result)
1436         {
1437                 case HeapTupleSelfUpdated:
1438                         return;
1439
1440                 case HeapTupleMayBeUpdated:
1441                         break;
1442
1443                 case HeapTupleUpdated:
1444                         if (XactIsoLevel == XACT_SERIALIZABLE)
1445                                 elog(ERROR, "Can't serialize access due to concurrent update");
1446                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1447                         {
1448                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1449                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1450
1451                                 if (!TupIsNull(epqslot))
1452                                 {
1453                                         *tupleid = ctid;
1454                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1455                                         slot = ExecStoreTuple(tuple,
1456                                                                         estate->es_junkFilter->jf_resultSlot,
1457                                                                                   InvalidBuffer, true);
1458                                         goto lreplace;
1459                                 }
1460                         }
1461                         /* tuple already deleted; nothing to do */
1462                         return;
1463
1464                 default:
1465                         elog(ERROR, "Unknown status %u from heap_update", result);
1466                         return;
1467         }
1468
1469         IncrReplaced();
1470         (estate->es_processed)++;
1471
1472         /*
1473          * Note: instead of having to update the old index tuples associated
1474          * with the heap tuple, all we do is form and insert new index tuples.
1475          * This is because replaces are actually deletes and inserts and index
1476          * tuple deletion is done automagically by the vacuum daemon. All we
1477          * do is insert new index tuples.  -cim 9/27/89
1478          */
1479
1480         /*
1481          * process indices
1482          *
1483          * heap_update updates a tuple in the base relation by invalidating it
1484          * and then appending a new tuple to the relation.      As a side effect,
1485          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1486          * field.  So we now insert index tuples using the new tupleid stored
1487          * there.
1488          */
1489
1490         numIndices = resultRelInfo->ri_NumIndices;
1491         if (numIndices > 0)
1492                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1493
1494         /* AFTER ROW UPDATE Triggers */
1495         if (resultRelInfo->ri_TrigDesc)
1496                 ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1497 }
1498
1499 static char *
1500 ExecRelCheck(ResultRelInfo *resultRelInfo,
1501                          TupleTableSlot *slot, EState *estate)
1502 {
1503         Relation        rel = resultRelInfo->ri_RelationDesc;
1504         int                     ncheck = rel->rd_att->constr->num_check;
1505         ConstrCheck *check = rel->rd_att->constr->check;
1506         ExprContext *econtext;
1507         MemoryContext oldContext;
1508         List       *qual;
1509         int                     i;
1510
1511         /*
1512          * If first time through for this result relation, build expression
1513          * nodetrees for rel's constraint expressions.  Keep them in the
1514          * per-query memory context so they'll survive throughout the query.
1515          */
1516         if (resultRelInfo->ri_ConstraintExprs == NULL)
1517         {
1518                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1519                 resultRelInfo->ri_ConstraintExprs =
1520                         (List **) palloc(ncheck * sizeof(List *));
1521                 for (i = 0; i < ncheck; i++)
1522                 {
1523                         qual = (List *) stringToNode(check[i].ccbin);
1524                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1525                 }
1526                 MemoryContextSwitchTo(oldContext);
1527         }
1528
1529         /*
1530          * We will use the EState's per-tuple context for evaluating
1531          * constraint expressions (creating it if it's not already there).
1532          */
1533         econtext = GetPerTupleExprContext(estate);
1534
1535         /* Arrange for econtext's scan tuple to be the tuple under test */
1536         econtext->ecxt_scantuple = slot;
1537
1538         /* And evaluate the constraints */
1539         for (i = 0; i < ncheck; i++)
1540         {
1541                 qual = resultRelInfo->ri_ConstraintExprs[i];
1542
1543                 /*
1544                  * NOTE: SQL92 specifies that a NULL result from a constraint
1545                  * expression is not to be treated as a failure.  Therefore, tell
1546                  * ExecQual to return TRUE for NULL.
1547                  */
1548                 if (!ExecQual(qual, econtext, true))
1549                         return check[i].ccname;
1550         }
1551
1552         /* NULL result means no error */
1553         return (char *) NULL;
1554 }
1555
1556 void
1557 ExecConstraints(char *caller, ResultRelInfo *resultRelInfo,
1558                                 TupleTableSlot *slot, EState *estate)
1559 {
1560         Relation        rel = resultRelInfo->ri_RelationDesc;
1561         HeapTuple       tuple = slot->val;
1562         TupleConstr *constr = rel->rd_att->constr;
1563
1564         Assert(constr);
1565
1566         if (constr->has_not_null)
1567         {
1568                 int                     natts = rel->rd_att->natts;
1569                 int                     attrChk;
1570
1571                 for (attrChk = 1; attrChk <= natts; attrChk++)
1572                 {
1573                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1574                                 heap_attisnull(tuple, attrChk))
1575                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1576                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1577                 }
1578         }
1579
1580         if (constr->num_check > 0)
1581         {
1582                 char       *failed;
1583
1584                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1585                         elog(ERROR, "%s: rejected due to CHECK constraint %s",
1586                                  caller, failed);
1587         }
1588 }
1589
1590 /*
1591  * Check a modified tuple to see if we want to process its updated version
1592  * under READ COMMITTED rules.
1593  *
1594  * See backend/executor/README for some info about how this works.
1595  */
1596 TupleTableSlot *
1597 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1598 {
1599         evalPlanQual *epq;
1600         EState     *epqstate;
1601         Relation        relation;
1602         HeapTupleData tuple;
1603         HeapTuple       copyTuple = NULL;
1604         int                     rtsize;
1605         bool            endNode;
1606
1607         Assert(rti != 0);
1608
1609         /*
1610          * find relation containing target tuple
1611          */
1612         if (estate->es_result_relation_info != NULL &&
1613                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1614                 relation = estate->es_result_relation_info->ri_RelationDesc;
1615         else
1616         {
1617                 List       *l;
1618
1619                 relation = NULL;
1620                 foreach(l, estate->es_rowMark)
1621                 {
1622                         if (((execRowMark *) lfirst(l))->rti == rti)
1623                         {
1624                                 relation = ((execRowMark *) lfirst(l))->relation;
1625                                 break;
1626                         }
1627                 }
1628                 if (relation == NULL)
1629                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1630         }
1631
1632         /*
1633          * fetch tid tuple
1634          *
1635          * Loop here to deal with updated or busy tuples
1636          */
1637         tuple.t_self = *tid;
1638         for (;;)
1639         {
1640                 Buffer          buffer;
1641
1642                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1643                 {
1644                         TransactionId xwait = SnapshotDirty->xmax;
1645
1646                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1647                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1648
1649                         /*
1650                          * If tuple is being updated by other transaction then we have
1651                          * to wait for its commit/abort.
1652                          */
1653                         if (TransactionIdIsValid(xwait))
1654                         {
1655                                 ReleaseBuffer(buffer);
1656                                 XactLockTableWait(xwait);
1657                                 continue;
1658                         }
1659
1660                         /*
1661                          * We got tuple - now copy it for use by recheck query.
1662                          */
1663                         copyTuple = heap_copytuple(&tuple);
1664                         ReleaseBuffer(buffer);
1665                         break;
1666                 }
1667
1668                 /*
1669                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1670                  * Note that it's possible to get invalid SnapshotDirty->tid if
1671                  * tuple updated by this transaction. Have we to check this ?
1672                  */
1673                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1674                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1675                 {
1676                         /* updated, so look at the updated copy */
1677                         tuple.t_self = SnapshotDirty->tid;
1678                         continue;
1679                 }
1680
1681                 /*
1682                  * Deleted or updated by this transaction; forget it.
1683                  */
1684                 return NULL;
1685         }
1686
1687         /*
1688          * For UPDATE/DELETE we have to return tid of actual row we're
1689          * executing PQ for.
1690          */
1691         *tid = tuple.t_self;
1692
1693         /*
1694          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1695          */
1696         epq = (evalPlanQual *) estate->es_evalPlanQual;
1697         rtsize = length(estate->es_range_table);
1698         endNode = true;
1699
1700         if (epq != NULL && epq->rti == 0)
1701         {
1702                 /* Top PQ stack entry is idle, so re-use it */
1703                 Assert(!(estate->es_useEvalPlan) &&
1704                            epq->estate.es_evalPlanQual == NULL);
1705                 epq->rti = rti;
1706                 endNode = false;
1707         }
1708
1709         /*
1710          * If this is request for another RTE - Ra, - then we have to check
1711          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1712          * updated again and we have to re-start old execution for Ra and
1713          * forget all what we done after Ra was suspended. Cool? -:))
1714          */
1715         if (epq != NULL && epq->rti != rti &&
1716                 epq->estate.es_evTuple[rti - 1] != NULL)
1717         {
1718                 do
1719                 {
1720                         evalPlanQual *oldepq;
1721
1722                         /* pop previous PlanQual from the stack */
1723                         epqstate = &(epq->estate);
1724                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1725                         Assert(oldepq->rti != 0);
1726                         /* stop execution */
1727                         ExecEndNode(epq->plan, NULL);
1728                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1729                         epqstate->es_tupleTable = NULL;
1730                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1731                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1732                         /* push current PQ to freePQ stack */
1733                         oldepq->free = epq;
1734                         epq = oldepq;
1735                         estate->es_evalPlanQual = (Pointer) epq;
1736                 } while (epq->rti != rti);
1737         }
1738
1739         /*
1740          * If we are requested for another RTE then we have to suspend
1741          * execution of current PlanQual and start execution for new one.
1742          */
1743         if (epq == NULL || epq->rti != rti)
1744         {
1745                 /* try to reuse plan used previously */
1746                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1747
1748                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1749                 {
1750                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1751                         newepq->free = NULL;
1752
1753                         /*
1754                          * Each stack level has its own copy of the plan tree.  This
1755                          * is wasteful, but necessary as long as plan nodes point to
1756                          * exec state nodes rather than vice versa.  Note that
1757                          * copyfuncs.c doesn't attempt to copy the exec state nodes,
1758                          * which is a good thing in this situation.
1759                          */
1760                         newepq->plan = copyObject(estate->es_origPlan);
1761
1762                         /*
1763                          * Init stack level's EState.  We share top level's copy of
1764                          * es_result_relations array and other non-changing status. We
1765                          * need our own tupletable, es_param_exec_vals, and other
1766                          * changeable state.
1767                          */
1768                         epqstate = &(newepq->estate);
1769                         memcpy(epqstate, estate, sizeof(EState));
1770                         epqstate->es_direction = ForwardScanDirection;
1771                         if (estate->es_origPlan->nParamExec > 0)
1772                                 epqstate->es_param_exec_vals = (ParamExecData *)
1773                                         palloc(estate->es_origPlan->nParamExec *
1774                                                    sizeof(ParamExecData));
1775                         epqstate->es_tupleTable = NULL;
1776                         epqstate->es_per_tuple_exprcontext = NULL;
1777
1778                         /*
1779                          * Each epqstate must have its own es_evTupleNull state, but
1780                          * all the stack entries share es_evTuple state.  This allows
1781                          * sub-rechecks to inherit the value being examined by an
1782                          * outer recheck.
1783                          */
1784                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1785                         if (epq == NULL)
1786                         {
1787                                 /* first PQ stack entry */
1788                                 epqstate->es_evTuple = (HeapTuple *)
1789                                         palloc(rtsize * sizeof(HeapTuple));
1790                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1791                         }
1792                         else
1793                         {
1794                                 /* later stack entries share the same storage */
1795                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1796                         }
1797                 }
1798                 else
1799                 {
1800                         /* recycle previously used EState */
1801                         epqstate = &(newepq->estate);
1802                 }
1803                 /* push current PQ to the stack */
1804                 epqstate->es_evalPlanQual = (Pointer) epq;
1805                 epq = newepq;
1806                 estate->es_evalPlanQual = (Pointer) epq;
1807                 epq->rti = rti;
1808                 endNode = false;
1809         }
1810
1811         Assert(epq->rti == rti);
1812         epqstate = &(epq->estate);
1813
1814         /*
1815          * Ok - we're requested for the same RTE.  Unfortunately we still have
1816          * to end and restart execution of the plan, because ExecReScan
1817          * wouldn't ensure that upper plan nodes would reset themselves.  We
1818          * could make that work if insertion of the target tuple were
1819          * integrated with the Param mechanism somehow, so that the upper plan
1820          * nodes know that their children's outputs have changed.
1821          */
1822         if (endNode)
1823         {
1824                 /* stop execution */
1825                 ExecEndNode(epq->plan, NULL);
1826                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1827                 epqstate->es_tupleTable = NULL;
1828         }
1829
1830         /*
1831          * free old RTE' tuple, if any, and store target tuple where
1832          * relation's scan node will see it
1833          */
1834         if (epqstate->es_evTuple[rti - 1] != NULL)
1835                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1836         epqstate->es_evTuple[rti - 1] = copyTuple;
1837
1838         /*
1839          * Initialize for new recheck query; be careful to copy down state
1840          * that might have changed in top EState.
1841          */
1842         epqstate->es_result_relation_info = estate->es_result_relation_info;
1843         epqstate->es_junkFilter = estate->es_junkFilter;
1844         if (estate->es_origPlan->nParamExec > 0)
1845                 memset(epqstate->es_param_exec_vals, 0,
1846                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1847         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1848         epqstate->es_useEvalPlan = false;
1849         Assert(epqstate->es_tupleTable == NULL);
1850         epqstate->es_tupleTable =
1851                 ExecCreateTupleTable(estate->es_tupleTable->size);
1852
1853         ExecInitNode(epq->plan, epqstate, NULL);
1854
1855         return EvalPlanQualNext(estate);
1856 }
1857
1858 static TupleTableSlot *
1859 EvalPlanQualNext(EState *estate)
1860 {
1861         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1862         EState     *epqstate = &(epq->estate);
1863         evalPlanQual *oldepq;
1864         TupleTableSlot *slot;
1865
1866         Assert(epq->rti != 0);
1867
1868 lpqnext:;
1869         slot = ExecProcNode(epq->plan, NULL);
1870
1871         /*
1872          * No more tuples for this PQ. Continue previous one.
1873          */
1874         if (TupIsNull(slot))
1875         {
1876                 /* stop execution */
1877                 ExecEndNode(epq->plan, NULL);
1878                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1879                 epqstate->es_tupleTable = NULL;
1880                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1881                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1882                 /* pop old PQ from the stack */
1883                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1884                 if (oldepq == (evalPlanQual *) NULL)
1885                 {
1886                         epq->rti = 0;           /* this is the first (oldest) */
1887                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1888                         return (NULL);          /* continue Query execution   */
1889                 }
1890                 Assert(oldepq->rti != 0);
1891                 /* push current PQ to freePQ stack */
1892                 oldepq->free = epq;
1893                 epq = oldepq;
1894                 epqstate = &(epq->estate);
1895                 estate->es_evalPlanQual = (Pointer) epq;
1896                 goto lpqnext;
1897         }
1898
1899         return (slot);
1900 }
1901
1902 static void
1903 EndEvalPlanQual(EState *estate)
1904 {
1905         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1906         EState     *epqstate = &(epq->estate);
1907         evalPlanQual *oldepq;
1908
1909         if (epq->rti == 0)                      /* plans already shutdowned */
1910         {
1911                 Assert(epq->estate.es_evalPlanQual == NULL);
1912                 return;
1913         }
1914
1915         for (;;)
1916         {
1917                 /* stop execution */
1918                 ExecEndNode(epq->plan, NULL);
1919                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1920                 epqstate->es_tupleTable = NULL;
1921                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1922                 {
1923                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1924                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1925                 }
1926                 /* pop old PQ from the stack */
1927                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1928                 if (oldepq == (evalPlanQual *) NULL)
1929                 {
1930                         epq->rti = 0;           /* this is the first (oldest) */
1931                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1932                         break;
1933                 }
1934                 Assert(oldepq->rti != 0);
1935                 /* push current PQ to freePQ stack */
1936                 oldepq->free = epq;
1937                 epq = oldepq;
1938                 epqstate = &(epq->estate);
1939                 estate->es_evalPlanQual = (Pointer) epq;
1940         }
1941 }