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

   1 /*-------------------------------------------------------------------------
   2  *
   3  * execMain.c
   4  *        top level executor interface routines
   5  *
   6  * INTERFACE ROUTINES
   7  *      ExecutorStart()
   8  *      ExecutorRun()
   9  *      ExecutorEnd()
  10  *
  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),
  12  *      ExecutorRun() and ExecutorEnd()
  13  *
  14  *      These three procedures are the external interfaces to the executor.
  15  *      In each case, the query descriptor and the execution state is required
  16  *       as arguments
  17  *
  18  *      ExecutorStart() must be called at the beginning of any execution of any
  19  *      query plan and ExecutorEnd() should always be called at the end of
  20  *      execution of a plan.
  21  *
  22  *      ExecutorRun accepts 'feature' and 'count' arguments that specify whether
  23  *      the plan is to be executed forwards, backwards, and for how many tuples.
  24  *
  25  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  26  * Portions Copyright (c) 1994, Regents of the University of California
  27  *
  28  *
  29  * IDENTIFICATION
  30  *        $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.148 2001/09/18 01:59:06 tgl Exp $
  31  *
  32  *-------------------------------------------------------------------------
  33  */
  34 #include "postgres.h"
  35
  36 #include "access/heapam.h"
  37 #include "catalog/heap.h"
  38 #include "commands/command.h"
  39 #include "commands/trigger.h"
  40 #include "executor/execdebug.h"
  41 #include "executor/execdefs.h"
  42 #include "miscadmin.h"
  43 #include "optimizer/var.h"
  44 #include "parser/parsetree.h"
  45 #include "utils/acl.h"
  46
  47
  48 /* decls for local routines only used within this module */
  49 static TupleDesc InitPlan(CmdType operation,
  50                  Query *parseTree,
  51                  Plan *plan,
  52                  EState *estate);
  53 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  54                                   Index resultRelationIndex,
  55                                   List *rangeTable,
  56                                   CmdType operation);
  57 static void EndPlan(Plan *plan, EState *estate);
  58 static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan,
  59                         CmdType operation,
  60                         long numberTuples,
  61                         ScanDirection direction,
  62                         DestReceiver *destfunc);
  63 static void ExecRetrieve(TupleTableSlot *slot,
  64                          DestReceiver *destfunc,
  65                          EState *estate);
  66 static void ExecAppend(TupleTableSlot *slot, ItemPointer tupleid,
  67                    EState *estate);
  68 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  69                    EState *estate);
  70 static void ExecReplace(TupleTableSlot *slot, ItemPointer tupleid,
  71                         EState *estate);
  72 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  73 static void EndEvalPlanQual(EState *estate);
  74 static void ExecCheckQueryPerms(CmdType operation, Query *parseTree,
  75                                         Plan *plan);
  76 static void ExecCheckPlanPerms(Plan *plan, List *rangeTable,
  77                                    CmdType operation);
  78 static void ExecCheckRTPerms(List *rangeTable, CmdType operation);
  79 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  80
  81 /* end of local decls */
  82
  83
  84 /* ----------------------------------------------------------------
  85  *              ExecutorStart
  86  *
  87  *              This routine must be called at the beginning of any execution of any
  88  *              query plan
  89  *
  90  *              returns a TupleDesc which describes the attributes of the tuples to
  91  *              be returned by the query.
  92  *
  93  * NB: the CurrentMemoryContext when this is called must be the context
  94  * to be used as the per-query context for the query plan.      ExecutorRun()
  95  * and ExecutorEnd() must be called in this same memory context.
  96  * ----------------------------------------------------------------
  97  */
  98 TupleDesc
  99 ExecutorStart(QueryDesc *queryDesc, EState *estate)
 100 {
 101         TupleDesc       result;
 102
 103         /* sanity checks */
 104         Assert(queryDesc != NULL);
 105
 106         if (queryDesc->plantree->nParamExec > 0)
 107         {
 108                 estate->es_param_exec_vals = (ParamExecData *)
 109                         palloc(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 110                 MemSet(estate->es_param_exec_vals, 0,
 111                            queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 112         }
 113
 114         /*
 115          * Make our own private copy of the current queries snapshot data
 116          */
 117         if (QuerySnapshot == NULL)
 118                 estate->es_snapshot = NULL;
 119         else
 120         {
 121                 estate->es_snapshot = (Snapshot) palloc(sizeof(SnapshotData));
 122                 memcpy(estate->es_snapshot, QuerySnapshot, sizeof(SnapshotData));
 123                 if (estate->es_snapshot->xcnt > 0)
 124                 {
 125                         estate->es_snapshot->xip = (TransactionId *)
 126                                 palloc(estate->es_snapshot->xcnt * sizeof(TransactionId));
 127                         memcpy(estate->es_snapshot->xip, QuerySnapshot->xip,
 128                                    estate->es_snapshot->xcnt * sizeof(TransactionId));
 129                 }
 130         }
 131
 132         /*
 133          * Initialize the plan
 134          */
 135         result = InitPlan(queryDesc->operation,
 136                                           queryDesc->parsetree,
 137                                           queryDesc->plantree,
 138                                           estate);
 139
 140         return result;
 141 }
 142
 143 /* ----------------------------------------------------------------
 144  *              ExecutorRun
 145  *
 146  *              This is the main routine of the executor module. It accepts
 147  *              the query descriptor from the traffic cop and executes the
 148  *              query plan.
 149  *
 150  *              ExecutorStart must have been called already.
 151  *
 152  *              the different features supported are:
 153  *                       EXEC_RUN:      retrieve all tuples in the forward direction
 154  *                       EXEC_FOR:      retrieve 'count' number of tuples in the forward dir
 155  *                       EXEC_BACK: retrieve 'count' number of tuples in the backward dir
 156  *                       EXEC_RETONE: return one tuple but don't 'retrieve' it
 157  *                                                 used in postquel function processing
 158  *
 159  *              Note: count = 0 is interpreted as "no limit".
 160  *
 161  * ----------------------------------------------------------------
 162  */
 163 TupleTableSlot *
 164 ExecutorRun(QueryDesc *queryDesc, EState *estate, int feature, long count)
 165 {
 166         CmdType         operation;
 167         Plan       *plan;
 168         TupleTableSlot *result;
 169         CommandDest dest;
 170         DestReceiver *destfunc;
 171
 172         /*
 173          * sanity checks
 174          */
 175         Assert(queryDesc != NULL);
 176
 177         /*
 178          * extract information from the query descriptor and the query
 179          * feature.
 180          */
 181         operation = queryDesc->operation;
 182         plan = queryDesc->plantree;
 183         dest = queryDesc->dest;
 184         destfunc = DestToFunction(dest);
 185         estate->es_processed = 0;
 186         estate->es_lastoid = InvalidOid;
 187
 188         /*
 189          * FIXME: the dest setup function ought to be handed the tuple desc
 190          * for the tuples to be output, but I'm not quite sure how to get that
 191          * info at this point.  For now, passing NULL is OK because no
 192          * existing dest setup function actually uses the pointer.
 193          */
 194         (*destfunc->setup) (destfunc, (TupleDesc) NULL);
 195
 196         switch (feature)
 197         {
 198                 case EXEC_RUN:
 199                         result = ExecutePlan(estate,
 200                                                                  plan,
 201                                                                  operation,
 202                                                                  count,
 203                                                                  ForwardScanDirection,
 204                                                                  destfunc);
 205                         break;
 206
 207                 case EXEC_FOR:
 208                         result = ExecutePlan(estate,
 209                                                                  plan,
 210                                                                  operation,
 211                                                                  count,
 212                                                                  ForwardScanDirection,
 213                                                                  destfunc);
 214                         break;
 215
 216                         /*
 217                          * retrieve next n "backward" tuples
 218                          */
 219                 case EXEC_BACK:
 220                         result = ExecutePlan(estate,
 221                                                                  plan,
 222                                                                  operation,
 223                                                                  count,
 224                                                                  BackwardScanDirection,
 225                                                                  destfunc);
 226                         break;
 227
 228                         /*
 229                          * return one tuple but don't "retrieve" it. (this is used by
 230                          * the rule manager..) -cim 9/14/89
 231                          */
 232                 case EXEC_RETONE:
 233                         result = ExecutePlan(estate,
 234                                                                  plan,
 235                                                                  operation,
 236                                                                  ONE_TUPLE,
 237                                                                  ForwardScanDirection,
 238                                                                  destfunc);
 239                         break;
 240
 241                 default:
 242                         elog(DEBUG, "ExecutorRun: Unknown feature %d", feature);
 243                         result = NULL;
 244                         break;
 245         }
 246
 247         (*destfunc->cleanup) (destfunc);
 248
 249         return result;
 250 }
 251
 252 /* ----------------------------------------------------------------
 253  *              ExecutorEnd
 254  *
 255  *              This routine must be called at the end of execution of any
 256  *              query plan
 257  * ----------------------------------------------------------------
 258  */
 259 void
 260 ExecutorEnd(QueryDesc *queryDesc, EState *estate)
 261 {
 262         /* sanity checks */
 263         Assert(queryDesc != NULL);
 264
 265         EndPlan(queryDesc->plantree, estate);
 266
 267         if (estate->es_snapshot != NULL)
 268         {
 269                 if (estate->es_snapshot->xcnt > 0)
 270                         pfree(estate->es_snapshot->xip);
 271                 pfree(estate->es_snapshot);
 272                 estate->es_snapshot = NULL;
 273         }
 274
 275         if (estate->es_param_exec_vals != NULL)
 276         {
 277                 pfree(estate->es_param_exec_vals);
 278                 estate->es_param_exec_vals = NULL;
 279         }
 280 }
 281
 282
 283 /*
 284  * ExecCheckQueryPerms
 285  *              Check access permissions for all relations referenced in a query.
 286  */
 287 static void
 288 ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan)
 289 {
 290
 291         /*
 292          * Check RTEs in the query's primary rangetable.
 293          */
 294         ExecCheckRTPerms(parseTree->rtable, operation);
 295
 296         /*
 297          * Search for subplans and APPEND nodes to check their rangetables.
 298          */
 299         ExecCheckPlanPerms(plan, parseTree->rtable, operation);
 300 }
 301
 302 /*
 303  * ExecCheckPlanPerms
 304  *              Recursively scan the plan tree to check access permissions in
 305  *              subplans.
 306  */
 307 static void
 308 ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation)
 309 {
 310         List       *subp;
 311
 312         if (plan == NULL)
 313                 return;
 314
 315         /* Check subplans, which we assume are plain SELECT queries */
 316
 317         foreach(subp, plan->initPlan)
 318         {
 319                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 320
 321                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 322                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 323         }
 324         foreach(subp, plan->subPlan)
 325         {
 326                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 327
 328                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 329                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 330         }
 331
 332         /* Check lower plan nodes */
 333
 334         ExecCheckPlanPerms(plan->lefttree, rangeTable, operation);
 335         ExecCheckPlanPerms(plan->righttree, rangeTable, operation);
 336
 337         /* Do node-type-specific checks */
 338
 339         switch (nodeTag(plan))
 340         {
 341                 case T_SubqueryScan:
 342                         {
 343                                 SubqueryScan *scan = (SubqueryScan *) plan;
 344                                 RangeTblEntry *rte;
 345
 346                                 /* Recursively check the subquery */
 347                                 rte = rt_fetch(scan->scan.scanrelid, rangeTable);
 348                                 Assert(rte->subquery != NULL);
 349                                 ExecCheckQueryPerms(operation, rte->subquery, scan->subplan);
 350                                 break;
 351                         }
 352                 case T_Append:
 353                         {
 354                                 Append     *app = (Append *) plan;
 355                                 List       *appendplans;
 356
 357                                 foreach(appendplans, app->appendplans)
 358                                 {
 359                                         ExecCheckPlanPerms((Plan *) lfirst(appendplans),
 360                                                                            rangeTable,
 361                                                                            operation);
 362                                 }
 363                                 break;
 364                         }
 365
 366                 default:
 367                         break;
 368         }
 369 }
 370
 371 /*
 372  * ExecCheckRTPerms
 373  *              Check access permissions for all relations listed in a range table.
 374  */
 375 static void
 376 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 377 {
 378         List       *lp;
 379
 380         foreach(lp, rangeTable)
 381         {
 382                 RangeTblEntry *rte = lfirst(lp);
 383
 384                 ExecCheckRTEPerms(rte, operation);
 385         }
 386 }
 387
 388 /*
 389  * ExecCheckRTEPerms
 390  *              Check access permissions for a single RTE.
 391  */
 392 static void
 393 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 394 {
 395         char       *relName;
 396         Oid                     userid;
 397         int32           aclcheck_result;
 398
 399         /*
 400          * If it's a subquery RTE, ignore it --- it will be checked when
 401          * ExecCheckPlanPerms finds the SubqueryScan node for it.
 402          */
 403         if (rte->subquery)
 404                 return;
 405
 406         relName = rte->relname;
 407
 408         /*
 409          * userid to check as: current user unless we have a setuid
 410          * indication.
 411          *
 412          * Note: GetUserId() is presently fast enough that there's no harm in
 413          * calling it separately for each RTE.  If that stops being true, we
 414          * could call it once in ExecCheckQueryPerms and pass the userid down
 415          * from there.  But for now, no need for the extra clutter.
 416          */
 417         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 418
 419 #define CHECK(MODE)             pg_aclcheck(relName, userid, MODE)
 420
 421         if (rte->checkForRead)
 422         {
 423                 aclcheck_result = CHECK(ACL_SELECT);
 424                 if (aclcheck_result != ACLCHECK_OK)
 425                         elog(ERROR, "%s: %s",
 426                                  relName, aclcheck_error_strings[aclcheck_result]);
 427         }
 428
 429         if (rte->checkForWrite)
 430         {
 431
 432                 /*
 433                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 434                  * Right now we don't distinguish that from true update as far as
 435                  * permissions checks are concerned.
 436                  */
 437                 switch (operation)
 438                 {
 439                         case CMD_INSERT:
 440                                 aclcheck_result = CHECK(ACL_INSERT);
 441                                 break;
 442                         case CMD_SELECT:
 443                         case CMD_UPDATE:
 444                                 aclcheck_result = CHECK(ACL_UPDATE);
 445                                 break;
 446                         case CMD_DELETE:
 447                                 aclcheck_result = CHECK(ACL_DELETE);
 448                                 break;
 449                         default:
 450                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 451                                          operation);
 452                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 453                                 break;
 454                 }
 455                 if (aclcheck_result != ACLCHECK_OK)
 456                         elog(ERROR, "%s: %s",
 457                                  relName, aclcheck_error_strings[aclcheck_result]);
 458         }
 459 }
 460
 461
 462 /* ===============================================================
 463  * ===============================================================
 464                                                  static routines follow
 465  * ===============================================================
 466  * ===============================================================
 467  */
 468
 469 typedef struct execRowMark
 470 {
 471         Relation        relation;
 472         Index           rti;
 473         char            resname[32];
 474 } execRowMark;
 475
 476 typedef struct evalPlanQual
 477 {
 478         Plan       *plan;
 479         Index           rti;
 480         EState          estate;
 481         struct evalPlanQual *free;
 482 } evalPlanQual;
 483
 484 /* ----------------------------------------------------------------
 485  *              InitPlan
 486  *
 487  *              Initializes the query plan: open files, allocate storage
 488  *              and start up the rule manager
 489  * ----------------------------------------------------------------
 490  */
 491 static TupleDesc
 492 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 493 {
 494         List       *rangeTable;
 495         Relation        intoRelationDesc;
 496         TupleDesc       tupType;
 497
 498         /*
 499          * Do permissions checks.
 500          */
 501         ExecCheckQueryPerms(operation, parseTree, plan);
 502
 503         /*
 504          * get information from query descriptor
 505          */
 506         rangeTable = parseTree->rtable;
 507
 508         /*
 509          * initialize the node's execution state
 510          */
 511         estate->es_range_table = rangeTable;
 512
 513         /*
 514          * if there is a result relation, initialize result relation stuff
 515          */
 516         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 517         {
 518                 List       *resultRelations = parseTree->resultRelations;
 519                 int                     numResultRelations;
 520                 ResultRelInfo *resultRelInfos;
 521
 522                 if (resultRelations != NIL)
 523                 {
 524
 525                         /*
 526                          * Multiple result relations (due to inheritance)
 527                          * parseTree->resultRelations identifies them all
 528                          */
 529                         ResultRelInfo *resultRelInfo;
 530
 531                         numResultRelations = length(resultRelations);
 532                         resultRelInfos = (ResultRelInfo *)
 533                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 534                         resultRelInfo = resultRelInfos;
 535                         while (resultRelations != NIL)
 536                         {
 537                                 initResultRelInfo(resultRelInfo,
 538                                                                   lfirsti(resultRelations),
 539                                                                   rangeTable,
 540                                                                   operation);
 541                                 resultRelInfo++;
 542                                 resultRelations = lnext(resultRelations);
 543                         }
 544                 }
 545                 else
 546                 {
 547
 548                         /*
 549                          * Single result relation identified by
 550                          * parseTree->resultRelation
 551                          */
 552                         numResultRelations = 1;
 553                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 554                         initResultRelInfo(resultRelInfos,
 555                                                           parseTree->resultRelation,
 556                                                           rangeTable,
 557                                                           operation);
 558                 }
 559
 560                 estate->es_result_relations = resultRelInfos;
 561                 estate->es_num_result_relations = numResultRelations;
 562                 /* Initialize to first or only result rel */
 563                 estate->es_result_relation_info = resultRelInfos;
 564         }
 565         else
 566         {
 567
 568                 /*
 569                  * if no result relation, then set state appropriately
 570                  */
 571                 estate->es_result_relations = NULL;
 572                 estate->es_num_result_relations = 0;
 573                 estate->es_result_relation_info = NULL;
 574         }
 575
 576         /*
 577          * Have to lock relations selected for update
 578          */
 579         estate->es_rowMark = NIL;
 580         if (parseTree->rowMarks != NIL)
 581         {
 582                 List       *l;
 583
 584                 foreach(l, parseTree->rowMarks)
 585                 {
 586                         Index           rti = lfirsti(l);
 587                         Oid                     relid = getrelid(rti, rangeTable);
 588                         Relation        relation;
 589                         execRowMark *erm;
 590
 591                         relation = heap_open(relid, RowShareLock);
 592                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 593                         erm->relation = relation;
 594                         erm->rti = rti;
 595                         sprintf(erm->resname, "ctid%u", rti);
 596                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 597                 }
 598         }
 599
 600         /*
 601          * initialize the executor "tuple" table.  We need slots for all the
 602          * plan nodes, plus possibly output slots for the junkfilter(s).
 603          * At this point we aren't sure if we need junkfilters, so just add
 604          * slots for them unconditionally.
 605          */
 606         {
 607                 int                     nSlots = ExecCountSlotsNode(plan);
 608
 609                 if (parseTree->resultRelations != NIL)
 610                         nSlots += length(parseTree->resultRelations);
 611                 else
 612                         nSlots += 1;
 613                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 614         }
 615
 616         /* mark EvalPlanQual not active */
 617         estate->es_origPlan = plan;
 618         estate->es_evalPlanQual = NULL;
 619         estate->es_evTuple = NULL;
 620         estate->es_evTupleNull = NULL;
 621         estate->es_useEvalPlan = false;
 622
 623         /*
 624          * initialize the private state information for all the nodes in the
 625          * query tree.  This opens files, allocates storage and leaves us
 626          * ready to start processing tuples.
 627          */
 628         ExecInitNode(plan, estate, NULL);
 629
 630         /*
 631          * Get the tuple descriptor describing the type of tuples to return.
 632          * (this is especially important if we are creating a relation with
 633          * "retrieve into")
 634          */
 635         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 636
 637         /*
 638          * Initialize the junk filter if needed. SELECT and INSERT queries
 639          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 640          * DELETE always need one, since there's always a junk 'ctid'
 641          * attribute present --- no need to look first.
 642          */
 643         {
 644                 bool            junk_filter_needed = false;
 645                 List       *tlist;
 646
 647                 switch (operation)
 648                 {
 649                         case CMD_SELECT:
 650                         case CMD_INSERT:
 651                                 foreach(tlist, plan->targetlist)
 652                                 {
 653                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 654
 655                                         if (tle->resdom->resjunk)
 656                                         {
 657                                                 junk_filter_needed = true;
 658                                                 break;
 659                                         }
 660                                 }
 661                                 break;
 662                         case CMD_UPDATE:
 663                         case CMD_DELETE:
 664                                 junk_filter_needed = true;
 665                                 break;
 666                         default:
 667                                 break;
 668                 }
 669
 670                 if (junk_filter_needed)
 671                 {
 672
 673                         /*
 674                          * If there are multiple result relations, each one needs its
 675                          * own junk filter.  Note this is only possible for
 676                          * UPDATE/DELETE, so we can't be fooled by some needing a
 677                          * filter and some not.
 678                          */
 679                         if (parseTree->resultRelations != NIL)
 680                         {
 681                                 List       *subplans;
 682                                 ResultRelInfo *resultRelInfo;
 683
 684                                 /* Top plan had better be an Append here. */
 685                                 Assert(IsA(plan, Append));
 686                                 Assert(((Append *) plan)->isTarget);
 687                                 subplans = ((Append *) plan)->appendplans;
 688                                 Assert(length(subplans) == estate->es_num_result_relations);
 689                                 resultRelInfo = estate->es_result_relations;
 690                                 while (subplans != NIL)
 691                                 {
 692                                         Plan       *subplan = (Plan *) lfirst(subplans);
 693                                         JunkFilter *j;
 694
 695                                         j = ExecInitJunkFilter(subplan->targetlist,
 696                                                                                    ExecGetTupType(subplan),
 697                                                                                    ExecAllocTableSlot(estate->es_tupleTable));
 698                                         resultRelInfo->ri_junkFilter = j;
 699                                         resultRelInfo++;
 700                                         subplans = lnext(subplans);
 701                                 }
 702
 703                                 /*
 704                                  * Set active junkfilter too; at this point ExecInitAppend
 705                                  * has already selected an active result relation...
 706                                  */
 707                                 estate->es_junkFilter =
 708                                         estate->es_result_relation_info->ri_junkFilter;
 709                         }
 710                         else
 711                         {
 712                                 /* Normal case with just one JunkFilter */
 713                                 JunkFilter *j;
 714
 715                                 j = ExecInitJunkFilter(plan->targetlist,
 716                                                                            tupType,
 717                                                                            ExecAllocTableSlot(estate->es_tupleTable));
 718                                 estate->es_junkFilter = j;
 719                                 if (estate->es_result_relation_info)
 720                                         estate->es_result_relation_info->ri_junkFilter = j;
 721
 722                                 /* For SELECT, want to return the cleaned tuple type */
 723                                 if (operation == CMD_SELECT)
 724                                         tupType = j->jf_cleanTupType;
 725                         }
 726                 }
 727                 else
 728                         estate->es_junkFilter = NULL;
 729         }
 730
 731         /*
 732          * initialize the "into" relation
 733          */
 734         intoRelationDesc = (Relation) NULL;
 735
 736         if (operation == CMD_SELECT)
 737         {
 738                 char       *intoName;
 739                 Oid                     intoRelationId;
 740                 TupleDesc       tupdesc;
 741
 742                 if (!parseTree->isPortal)
 743                 {
 744
 745                         /*
 746                          * a select into table
 747                          */
 748                         if (parseTree->into != NULL)
 749                         {
 750
 751                                 /*
 752                                  * create the "into" relation
 753                                  */
 754                                 intoName = parseTree->into;
 755
 756                                 /*
 757                                  * have to copy tupType to get rid of constraints
 758                                  */
 759                                 tupdesc = CreateTupleDescCopy(tupType);
 760
 761                                 intoRelationId =
 762                                         heap_create_with_catalog(intoName,
 763                                                                                          tupdesc,
 764                                                                                          RELKIND_RELATION, true,
 765                                                                                          parseTree->isTemp,
 766                                                                                          allowSystemTableMods);
 767
 768                                 FreeTupleDesc(tupdesc);
 769
 770                                 /*
 771                                  * Advance command counter so that the newly-created
 772                                  * relation's catalog tuples will be visible to heap_open.
 773                                  */
 774                                 CommandCounterIncrement();
 775
 776                                 /*
 777                                  * If necessary, create a TOAST table for the into
 778                                  * relation. Note that AlterTableCreateToastTable ends
 779                                  * with CommandCounterIncrement(), so that the TOAST table
 780                                  * will be visible for insertion.
 781                                  */
 782                                 AlterTableCreateToastTable(intoName, true);
 783
 784                                 intoRelationDesc = heap_open(intoRelationId,
 785                                                                                          AccessExclusiveLock);
 786                         }
 787                 }
 788         }
 789
 790         estate->es_into_relation_descriptor = intoRelationDesc;
 791
 792         return tupType;
 793 }
 794
 795 /*
 796  * Initialize ResultRelInfo data for one result relation
 797  */
 798 static void
 799 initResultRelInfo(ResultRelInfo *resultRelInfo,
 800                                   Index resultRelationIndex,
 801                                   List *rangeTable,
 802                                   CmdType operation)
 803 {
 804         Oid                     resultRelationOid;
 805         Relation        resultRelationDesc;
 806
 807         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 808         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 809
 810         switch (resultRelationDesc->rd_rel->relkind)
 811         {
 812                 case RELKIND_SEQUENCE:
 813                         elog(ERROR, "You can't change sequence relation %s",
 814                                  RelationGetRelationName(resultRelationDesc));
 815                         break;
 816                 case RELKIND_TOASTVALUE:
 817                         elog(ERROR, "You can't change toast relation %s",
 818                                  RelationGetRelationName(resultRelationDesc));
 819                         break;
 820                 case RELKIND_VIEW:
 821                         elog(ERROR, "You can't change view relation %s",
 822                                  RelationGetRelationName(resultRelationDesc));
 823                         break;
 824         }
 825
 826         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 827         resultRelInfo->type = T_ResultRelInfo;
 828         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 829         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 830         resultRelInfo->ri_NumIndices = 0;
 831         resultRelInfo->ri_IndexRelationDescs = NULL;
 832         resultRelInfo->ri_IndexRelationInfo = NULL;
 833         resultRelInfo->ri_TrigDesc = resultRelationDesc->trigdesc;
 834         resultRelInfo->ri_TrigFunctions = NULL;
 835         resultRelInfo->ri_ConstraintExprs = NULL;
 836         resultRelInfo->ri_junkFilter = NULL;
 837
 838         /*
 839          * If there are indices on the result relation, open them and save
 840          * descriptors in the result relation info, so that we can add new
 841          * index entries for the tuples we add/update.  We need not do this
 842          * for a DELETE, however, since deletion doesn't affect indexes.
 843          */
 844         if (resultRelationDesc->rd_rel->relhasindex &&
 845                 operation != CMD_DELETE)
 846                 ExecOpenIndices(resultRelInfo);
 847 }
 848
 849 /* ----------------------------------------------------------------
 850  *              EndPlan
 851  *
 852  *              Cleans up the query plan -- closes files and free up storages
 853  * ----------------------------------------------------------------
 854  */
 855 static void
 856 EndPlan(Plan *plan, EState *estate)
 857 {
 858         ResultRelInfo *resultRelInfo;
 859         int                     i;
 860         List       *l;
 861
 862         /*
 863          * shut down any PlanQual processing we were doing
 864          */
 865         if (estate->es_evalPlanQual != NULL)
 866                 EndEvalPlanQual(estate);
 867
 868         /*
 869          * shut down the node-type-specific query processing
 870          */
 871         ExecEndNode(plan, NULL);
 872
 873         /*
 874          * destroy the executor "tuple" table.
 875          */
 876         ExecDropTupleTable(estate->es_tupleTable, true);
 877         estate->es_tupleTable = NULL;
 878
 879         /*
 880          * close the result relation(s) if any, but hold locks until xact
 881          * commit.      Also clean up junkfilters if present.
 882          */
 883         resultRelInfo = estate->es_result_relations;
 884         for (i = estate->es_num_result_relations; i > 0; i--)
 885         {
 886                 /* Close indices and then the relation itself */
 887                 ExecCloseIndices(resultRelInfo);
 888                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 889                 /* Delete the junkfilter if any */
 890                 if (resultRelInfo->ri_junkFilter != NULL)
 891                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 892                 resultRelInfo++;
 893         }
 894
 895         /*
 896          * close the "into" relation if necessary, again keeping lock
 897          */
 898         if (estate->es_into_relation_descriptor != NULL)
 899                 heap_close(estate->es_into_relation_descriptor, NoLock);
 900
 901         /*
 902          * There might be a junkfilter without a result relation.
 903          */
 904         if (estate->es_num_result_relations == 0 &&
 905                 estate->es_junkFilter != NULL)
 906         {
 907                 ExecFreeJunkFilter(estate->es_junkFilter);
 908                 estate->es_junkFilter = NULL;
 909         }
 910
 911         /*
 912          * close any relations selected FOR UPDATE, again keeping locks
 913          */
 914         foreach(l, estate->es_rowMark)
 915         {
 916                 execRowMark *erm = lfirst(l);
 917
 918                 heap_close(erm->relation, NoLock);
 919         }
 920 }
 921
 922 /* ----------------------------------------------------------------
 923  *              ExecutePlan
 924  *
 925  *              processes the query plan to retrieve 'numberTuples' tuples in the
 926  *              direction specified.
 927  *              Retrieves all tuples if tupleCount is 0
 928  *
 929  *              result is either a slot containing the last tuple in the case
 930  *              of a RETRIEVE or NULL otherwise.
 931  *
 932  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 933  * user can see it
 934  * ----------------------------------------------------------------
 935  */
 936 static TupleTableSlot *
 937 ExecutePlan(EState *estate,
 938                         Plan *plan,
 939                         CmdType operation,
 940                         long numberTuples,
 941                         ScanDirection direction,
 942                         DestReceiver *destfunc)
 943 {
 944         JunkFilter *junkfilter;
 945         TupleTableSlot *slot;
 946         ItemPointer tupleid = NULL;
 947         ItemPointerData tuple_ctid;
 948         long            current_tuple_count;
 949         TupleTableSlot *result;
 950
 951         /*
 952          * initialize local variables
 953          */
 954         slot = NULL;
 955         current_tuple_count = 0;
 956         result = NULL;
 957
 958         /*
 959          * Set the direction.
 960          */
 961         estate->es_direction = direction;
 962
 963         /*
 964          * Loop until we've processed the proper number of tuples from the
 965          * plan.
 966          */
 967
 968         for (;;)
 969         {
 970                 /* Reset the per-output-tuple exprcontext */
 971                 ResetPerTupleExprContext(estate);
 972
 973                 /*
 974                  * Execute the plan and obtain a tuple
 975                  */
 976 lnext:  ;
 977                 if (estate->es_useEvalPlan)
 978                 {
 979                         slot = EvalPlanQualNext(estate);
 980                         if (TupIsNull(slot))
 981                                 slot = ExecProcNode(plan, NULL);
 982                 }
 983                 else
 984                         slot = ExecProcNode(plan, NULL);
 985
 986                 /*
 987                  * if the tuple is null, then we assume there is nothing more to
 988                  * process so we just return null...
 989                  */
 990                 if (TupIsNull(slot))
 991                 {
 992                         result = NULL;
 993                         break;
 994                 }
 995
 996                 /*
 997                  * if we have a junk filter, then project a new tuple with the
 998                  * junk removed.
 999                  *
1000                  * Store this new "clean" tuple in the junkfilter's resultSlot.
1001                  * (Formerly, we stored it back over the "dirty" tuple, which is
1002                  * WRONG because that tuple slot has the wrong descriptor.)
1003                  *
1004                  * Also, extract all the junk information we need.
1005                  */
1006                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
1007                 {
1008                         Datum           datum;
1009                         HeapTuple       newTuple;
1010                         bool            isNull;
1011
1012                         /*
1013                          * extract the 'ctid' junk attribute.
1014                          */
1015                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1016                         {
1017                                 if (!ExecGetJunkAttribute(junkfilter,
1018                                                                                   slot,
1019                                                                                   "ctid",
1020                                                                                   &datum,
1021                                                                                   &isNull))
1022                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1023
1024                                 /* shouldn't ever get a null result... */
1025                                 if (isNull)
1026                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1027
1028                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1029                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1030                                                                                  * ctid!! */
1031                                 tupleid = &tuple_ctid;
1032                         }
1033                         else if (estate->es_rowMark != NIL)
1034                         {
1035                                 List       *l;
1036
1037                 lmark:  ;
1038                                 foreach(l, estate->es_rowMark)
1039                                 {
1040                                         execRowMark *erm = lfirst(l);
1041                                         Buffer          buffer;
1042                                         HeapTupleData tuple;
1043                                         TupleTableSlot *newSlot;
1044                                         int                     test;
1045
1046                                         if (!ExecGetJunkAttribute(junkfilter,
1047                                                                                           slot,
1048                                                                                           erm->resname,
1049                                                                                           &datum,
1050                                                                                           &isNull))
1051                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1052                                                          erm->resname);
1053
1054                                         /* shouldn't ever get a null result... */
1055                                         if (isNull)
1056                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1057                                                          erm->resname);
1058
1059                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1060                                         test = heap_mark4update(erm->relation, &tuple, &buffer);
1061                                         ReleaseBuffer(buffer);
1062                                         switch (test)
1063                                         {
1064                                                 case HeapTupleSelfUpdated:
1065                                                 case HeapTupleMayBeUpdated:
1066                                                         break;
1067
1068                                                 case HeapTupleUpdated:
1069                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1070                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1071                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1072                                                                   (ItemPointer) DatumGetPointer(datum))))
1073                                                         {
1074                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1075                                                                 if (!(TupIsNull(newSlot)))
1076                                                                 {
1077                                                                         slot = newSlot;
1078                                                                         estate->es_useEvalPlan = true;
1079                                                                         goto lmark;
1080                                                                 }
1081                                                         }
1082
1083                                                         /*
1084                                                          * if tuple was deleted or PlanQual failed for
1085                                                          * updated tuple - we must not return this
1086                                                          * tuple!
1087                                                          */
1088                                                         goto lnext;
1089
1090                                                 default:
1091                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1092                                                         return (NULL);
1093                                         }
1094                                 }
1095                         }
1096
1097                         /*
1098                          * Finally create a new "clean" tuple with all junk attributes
1099                          * removed
1100                          */
1101                         newTuple = ExecRemoveJunk(junkfilter, slot);
1102
1103                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1104                                                                   junkfilter->jf_resultSlot, /* dest slot */
1105                                                                   InvalidBuffer,                /* this tuple has no
1106                                                                                                                  * buffer */
1107                                                                   true);                /* tuple should be pfreed */
1108                 }                                               /* if (junkfilter... */
1109
1110                 /*
1111                  * now that we have a tuple, do the appropriate thing with it..
1112                  * either return it to the user, add it to a relation someplace,
1113                  * delete it from a relation, or modify some of its attributes.
1114                  */
1115
1116                 switch (operation)
1117                 {
1118                         case CMD_SELECT:
1119                                 ExecRetrieve(slot,              /* slot containing tuple */
1120                                                          destfunc,      /* destination's tuple-receiver
1121                                                                                  * obj */
1122                                                          estate);       /* */
1123                                 result = slot;
1124                                 break;
1125
1126                         case CMD_INSERT:
1127                                 ExecAppend(slot, tupleid, estate);
1128                                 result = NULL;
1129                                 break;
1130
1131                         case CMD_DELETE:
1132                                 ExecDelete(slot, tupleid, estate);
1133                                 result = NULL;
1134                                 break;
1135
1136                         case CMD_UPDATE:
1137                                 ExecReplace(slot, tupleid, estate);
1138                                 result = NULL;
1139                                 break;
1140
1141                         default:
1142                                 elog(DEBUG, "ExecutePlan: unknown operation in queryDesc");
1143                                 result = NULL;
1144                                 break;
1145                 }
1146
1147                 /*
1148                  * check our tuple count.. if we've processed the proper number
1149                  * then quit, else loop again and process more tuples..
1150                  */
1151                 current_tuple_count++;
1152                 if (numberTuples == current_tuple_count)
1153                         break;
1154         }
1155
1156         /*
1157          * here, result is either a slot containing a tuple in the case of a
1158          * RETRIEVE or NULL otherwise.
1159          */
1160         return result;
1161 }
1162
1163 /* ----------------------------------------------------------------
1164  *              ExecRetrieve
1165  *
1166  *              RETRIEVEs are easy.. we just pass the tuple to the appropriate
1167  *              print function.  The only complexity is when we do a
1168  *              "retrieve into", in which case we insert the tuple into
1169  *              the appropriate relation (note: this is a newly created relation
1170  *              so we don't need to worry about indices or locks.)
1171  * ----------------------------------------------------------------
1172  */
1173 static void
1174 ExecRetrieve(TupleTableSlot *slot,
1175                          DestReceiver *destfunc,
1176                          EState *estate)
1177 {
1178         HeapTuple       tuple;
1179         TupleDesc       attrtype;
1180
1181         /*
1182          * get the heap tuple out of the tuple table slot
1183          */
1184         tuple = slot->val;
1185         attrtype = slot->ttc_tupleDescriptor;
1186
1187         /*
1188          * insert the tuple into the "into relation"
1189          */
1190         if (estate->es_into_relation_descriptor != NULL)
1191         {
1192                 heap_insert(estate->es_into_relation_descriptor, tuple);
1193                 IncrAppended();
1194         }
1195
1196         /*
1197          * send the tuple to the front end (or the screen)
1198          */
1199         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1200         IncrRetrieved();
1201         (estate->es_processed)++;
1202 }
1203
1204 /* ----------------------------------------------------------------
1205  *              ExecAppend
1206  *
1207  *              APPENDs are trickier.. we have to insert the tuple into
1208  *              the base relation and insert appropriate tuples into the
1209  *              index relations.
1210  * ----------------------------------------------------------------
1211  */
1212
1213 static void
1214 ExecAppend(TupleTableSlot *slot,
1215                    ItemPointer tupleid,
1216                    EState *estate)
1217 {
1218         HeapTuple       tuple;
1219         ResultRelInfo *resultRelInfo;
1220         Relation        resultRelationDesc;
1221         int                     numIndices;
1222         Oid                     newId;
1223
1224         /*
1225          * get the heap tuple out of the tuple table slot
1226          */
1227         tuple = slot->val;
1228
1229         /*
1230          * get information on the (current) result relation
1231          */
1232         resultRelInfo = estate->es_result_relation_info;
1233         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1234
1235         /* BEFORE ROW INSERT Triggers */
1236         if (resultRelInfo->ri_TrigDesc &&
1237                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1238         {
1239                 HeapTuple       newtuple;
1240
1241                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1242
1243                 if (newtuple == NULL)   /* "do nothing" */
1244                         return;
1245
1246                 if (newtuple != tuple)  /* modified by Trigger(s) */
1247                 {
1248
1249                         /*
1250                          * Insert modified tuple into tuple table slot, replacing the
1251                          * original.  We assume that it was allocated in per-tuple
1252                          * memory context, and therefore will go away by itself. The
1253                          * tuple table slot should not try to clear it.
1254                          */
1255                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1256                         tuple = newtuple;
1257                 }
1258         }
1259
1260         /*
1261          * Check the constraints of the tuple
1262          */
1263         if (resultRelationDesc->rd_att->constr)
1264                 ExecConstraints("ExecAppend", resultRelInfo, slot, estate);
1265
1266         /*
1267          * insert the tuple
1268          */
1269         newId = heap_insert(resultRelationDesc, tuple);
1270
1271         IncrAppended();
1272         (estate->es_processed)++;
1273         estate->es_lastoid = newId;
1274         setLastTid(&(tuple->t_self));
1275
1276         /*
1277          * process indices
1278          *
1279          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1280          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1281          * field.
1282          */
1283         numIndices = resultRelInfo->ri_NumIndices;
1284         if (numIndices > 0)
1285                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1286
1287         /* AFTER ROW INSERT Triggers */
1288         if (resultRelInfo->ri_TrigDesc)
1289                 ExecARInsertTriggers(estate, resultRelInfo, tuple);
1290 }
1291
1292 /* ----------------------------------------------------------------
1293  *              ExecDelete
1294  *
1295  *              DELETE is like append, we delete the tuple and its
1296  *              index tuples.
1297  * ----------------------------------------------------------------
1298  */
1299 static void
1300 ExecDelete(TupleTableSlot *slot,
1301                    ItemPointer tupleid,
1302                    EState *estate)
1303 {
1304         ResultRelInfo *resultRelInfo;
1305         Relation        resultRelationDesc;
1306         ItemPointerData ctid;
1307         int                     result;
1308
1309         /*
1310          * get information on the (current) result relation
1311          */
1312         resultRelInfo = estate->es_result_relation_info;
1313         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1314
1315         /* BEFORE ROW DELETE Triggers */
1316         if (resultRelInfo->ri_TrigDesc &&
1317                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1318         {
1319                 bool            dodelete;
1320
1321                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1322
1323                 if (!dodelete)                  /* "do nothing" */
1324                         return;
1325         }
1326
1327         /*
1328          * delete the tuple
1329          */
1330 ldelete:;
1331         result = heap_delete(resultRelationDesc, tupleid, &ctid);
1332         switch (result)
1333         {
1334                 case HeapTupleSelfUpdated:
1335                         return;
1336
1337                 case HeapTupleMayBeUpdated:
1338                         break;
1339
1340                 case HeapTupleUpdated:
1341                         if (XactIsoLevel == XACT_SERIALIZABLE)
1342                                 elog(ERROR, "Can't serialize access due to concurrent update");
1343                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1344                         {
1345                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1346                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1347
1348                                 if (!TupIsNull(epqslot))
1349                                 {
1350                                         *tupleid = ctid;
1351                                         goto ldelete;
1352                                 }
1353                         }
1354                         /* tuple already deleted; nothing to do */
1355                         return;
1356
1357                 default:
1358                         elog(ERROR, "Unknown status %u from heap_delete", result);
1359                         return;
1360         }
1361
1362         IncrDeleted();
1363         (estate->es_processed)++;
1364
1365         /*
1366          * Note: Normally one would think that we have to delete index tuples
1367          * associated with the heap tuple now..
1368          *
1369          * ... but in POSTGRES, we have no need to do this because the vacuum
1370          * daemon automatically opens an index scan and deletes index tuples
1371          * when it finds deleted heap tuples. -cim 9/27/89
1372          */
1373
1374         /* AFTER ROW DELETE Triggers */
1375         if (resultRelInfo->ri_TrigDesc)
1376                 ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1377 }
1378
1379 /* ----------------------------------------------------------------
1380  *              ExecReplace
1381  *
1382  *              note: we can't run replace queries with transactions
1383  *              off because replaces are actually appends and our
1384  *              scan will mistakenly loop forever, replacing the tuple
1385  *              it just appended..      This should be fixed but until it
1386  *              is, we don't want to get stuck in an infinite loop
1387  *              which corrupts your database..
1388  * ----------------------------------------------------------------
1389  */
1390 static void
1391 ExecReplace(TupleTableSlot *slot,
1392                         ItemPointer tupleid,
1393                         EState *estate)
1394 {
1395         HeapTuple       tuple;
1396         ResultRelInfo *resultRelInfo;
1397         Relation        resultRelationDesc;
1398         ItemPointerData ctid;
1399         int                     result;
1400         int                     numIndices;
1401
1402         /*
1403          * abort the operation if not running transactions
1404          */
1405         if (IsBootstrapProcessingMode())
1406         {
1407                 elog(NOTICE, "ExecReplace: replace can't run without transactions");
1408                 return;
1409         }
1410
1411         /*
1412          * get the heap tuple out of the tuple table slot
1413          */
1414         tuple = slot->val;
1415
1416         /*
1417          * get information on the (current) result relation
1418          */
1419         resultRelInfo = estate->es_result_relation_info;
1420         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1421
1422         /* BEFORE ROW UPDATE Triggers */
1423         if (resultRelInfo->ri_TrigDesc &&
1424                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1425         {
1426                 HeapTuple       newtuple;
1427
1428                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1429                                                                                 tupleid, tuple);
1430
1431                 if (newtuple == NULL)   /* "do nothing" */
1432                         return;
1433
1434                 if (newtuple != tuple)  /* modified by Trigger(s) */
1435                 {
1436
1437                         /*
1438                          * Insert modified tuple into tuple table slot, replacing the
1439                          * original.  We assume that it was allocated in per-tuple
1440                          * memory context, and therefore will go away by itself. The
1441                          * tuple table slot should not try to clear it.
1442                          */
1443                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1444                         tuple = newtuple;
1445                 }
1446         }
1447
1448         /*
1449          * Check the constraints of the tuple
1450          *
1451          * If we generate a new candidate tuple after EvalPlanQual testing,
1452          * we must loop back here and recheck constraints.  (We don't need to
1453          * redo triggers, however.  If there are any BEFORE triggers then
1454          * trigger.c will have done mark4update to lock the correct tuple,
1455          * so there's no need to do them again.)
1456          */
1457 lreplace:;
1458         if (resultRelationDesc->rd_att->constr)
1459                 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1460
1461         /*
1462          * replace the heap tuple
1463          */
1464         result = heap_update(resultRelationDesc, tupleid, tuple, &ctid);
1465         switch (result)
1466         {
1467                 case HeapTupleSelfUpdated:
1468                         return;
1469
1470                 case HeapTupleMayBeUpdated:
1471                         break;
1472
1473                 case HeapTupleUpdated:
1474                         if (XactIsoLevel == XACT_SERIALIZABLE)
1475                                 elog(ERROR, "Can't serialize access due to concurrent update");
1476                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1477                         {
1478                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1479                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1480
1481                                 if (!TupIsNull(epqslot))
1482                                 {
1483                                         *tupleid = ctid;
1484                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1485                                         slot = ExecStoreTuple(tuple,
1486                                                                                   estate->es_junkFilter->jf_resultSlot,
1487                                                                                   InvalidBuffer, true);
1488                                         goto lreplace;
1489                                 }
1490                         }
1491                         /* tuple already deleted; nothing to do */
1492                         return;
1493
1494                 default:
1495                         elog(ERROR, "Unknown status %u from heap_update", result);
1496                         return;
1497         }
1498
1499         IncrReplaced();
1500         (estate->es_processed)++;
1501
1502         /*
1503          * Note: instead of having to update the old index tuples associated
1504          * with the heap tuple, all we do is form and insert new index tuples.
1505          * This is because replaces are actually deletes and inserts and index
1506          * tuple deletion is done automagically by the vacuum daemon. All we
1507          * do is insert new index tuples.  -cim 9/27/89
1508          */
1509
1510         /*
1511          * process indices
1512          *
1513          * heap_update updates a tuple in the base relation by invalidating it
1514          * and then appending a new tuple to the relation.      As a side effect,
1515          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1516          * field.  So we now insert index tuples using the new tupleid stored
1517          * there.
1518          */
1519
1520         numIndices = resultRelInfo->ri_NumIndices;
1521         if (numIndices > 0)
1522                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, true);
1523
1524         /* AFTER ROW UPDATE Triggers */
1525         if (resultRelInfo->ri_TrigDesc)
1526                 ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1527 }
1528
1529 static char *
1530 ExecRelCheck(ResultRelInfo *resultRelInfo,
1531                          TupleTableSlot *slot, EState *estate)
1532 {
1533         Relation        rel = resultRelInfo->ri_RelationDesc;
1534         int                     ncheck = rel->rd_att->constr->num_check;
1535         ConstrCheck *check = rel->rd_att->constr->check;
1536         ExprContext *econtext;
1537         MemoryContext oldContext;
1538         List       *qual;
1539         int                     i;
1540
1541         /*
1542          * If first time through for this result relation, build expression
1543          * nodetrees for rel's constraint expressions.  Keep them in the
1544          * per-query memory context so they'll survive throughout the query.
1545          */
1546         if (resultRelInfo->ri_ConstraintExprs == NULL)
1547         {
1548                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1549                 resultRelInfo->ri_ConstraintExprs =
1550                         (List **) palloc(ncheck * sizeof(List *));
1551                 for (i = 0; i < ncheck; i++)
1552                 {
1553                         qual = (List *) stringToNode(check[i].ccbin);
1554                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1555                 }
1556                 MemoryContextSwitchTo(oldContext);
1557         }
1558
1559         /*
1560          * We will use the EState's per-tuple context for evaluating
1561          * constraint expressions (creating it if it's not already there).
1562          */
1563         econtext = GetPerTupleExprContext(estate);
1564
1565         /* Arrange for econtext's scan tuple to be the tuple under test */
1566         econtext->ecxt_scantuple = slot;
1567
1568         /* And evaluate the constraints */
1569         for (i = 0; i < ncheck; i++)
1570         {
1571                 qual = resultRelInfo->ri_ConstraintExprs[i];
1572
1573                 /*
1574                  * NOTE: SQL92 specifies that a NULL result from a constraint
1575                  * expression is not to be treated as a failure.  Therefore, tell
1576                  * ExecQual to return TRUE for NULL.
1577                  */
1578                 if (!ExecQual(qual, econtext, true))
1579                         return check[i].ccname;
1580         }
1581
1582         /* NULL result means no error */
1583         return (char *) NULL;
1584 }
1585
1586 void
1587 ExecConstraints(char *caller, ResultRelInfo *resultRelInfo,
1588                                 TupleTableSlot *slot, EState *estate)
1589 {
1590         Relation        rel = resultRelInfo->ri_RelationDesc;
1591         HeapTuple       tuple = slot->val;
1592         TupleConstr *constr = rel->rd_att->constr;
1593
1594         Assert(constr);
1595
1596         if (constr->has_not_null)
1597         {
1598                 int                     natts = rel->rd_att->natts;
1599                 int                     attrChk;
1600
1601                 for (attrChk = 1; attrChk <= natts; attrChk++)
1602                 {
1603                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1604                                 heap_attisnull(tuple, attrChk))
1605                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1606                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1607                 }
1608         }
1609
1610         if (constr->num_check > 0)
1611         {
1612                 char       *failed;
1613
1614                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1615                         elog(ERROR, "%s: rejected due to CHECK constraint %s",
1616                                  caller, failed);
1617         }
1618 }
1619
1620 /*
1621  * Check a modified tuple to see if we want to process its updated version
1622  * under READ COMMITTED rules.
1623  *
1624  * See backend/executor/README for some info about how this works.
1625  */
1626 TupleTableSlot *
1627 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1628 {
1629         evalPlanQual *epq;
1630         EState     *epqstate;
1631         Relation        relation;
1632         HeapTupleData tuple;
1633         HeapTuple       copyTuple = NULL;
1634         int                     rtsize;
1635         bool            endNode;
1636
1637         Assert(rti != 0);
1638
1639         /*
1640          * find relation containing target tuple
1641          */
1642         if (estate->es_result_relation_info != NULL &&
1643                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1644         {
1645                 relation = estate->es_result_relation_info->ri_RelationDesc;
1646         }
1647         else
1648         {
1649                 List       *l;
1650
1651                 relation = NULL;
1652                 foreach(l, estate->es_rowMark)
1653                 {
1654                         if (((execRowMark *) lfirst(l))->rti == rti)
1655                         {
1656                                 relation = ((execRowMark *) lfirst(l))->relation;
1657                                 break;
1658                         }
1659                 }
1660                 if (relation == NULL)
1661                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1662         }
1663
1664         /*
1665          * fetch tid tuple
1666          *
1667          * Loop here to deal with updated or busy tuples
1668          */
1669         tuple.t_self = *tid;
1670         for (;;)
1671         {
1672                 Buffer          buffer;
1673
1674                 heap_fetch(relation, SnapshotDirty, &tuple, &buffer, NULL);
1675                 if (tuple.t_data != NULL)
1676                 {
1677                         TransactionId xwait = SnapshotDirty->xmax;
1678
1679                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1680                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1681
1682                         /*
1683                          * If tuple is being updated by other transaction then we have
1684                          * to wait for its commit/abort.
1685                          */
1686                         if (TransactionIdIsValid(xwait))
1687                         {
1688                                 ReleaseBuffer(buffer);
1689                                 XactLockTableWait(xwait);
1690                                 continue;
1691                         }
1692
1693                         /*
1694                          * We got tuple - now copy it for use by recheck query.
1695                          */
1696                         copyTuple = heap_copytuple(&tuple);
1697                         ReleaseBuffer(buffer);
1698                         break;
1699                 }
1700
1701                 /*
1702                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1703                  * Note that it's possible to get invalid SnapshotDirty->tid if
1704                  * tuple updated by this transaction. Have we to check this ?
1705                  */
1706                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1707                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1708                 {
1709                         /* updated, so look at the updated copy */
1710                         tuple.t_self = SnapshotDirty->tid;
1711                         continue;
1712                 }
1713
1714                 /*
1715                  * Deleted or updated by this transaction; forget it.
1716                  */
1717                 return NULL;
1718         }
1719
1720         /*
1721          * For UPDATE/DELETE we have to return tid of actual row we're
1722          * executing PQ for.
1723          */
1724         *tid = tuple.t_self;
1725
1726         /*
1727          * Need to run a recheck subquery.  Find or create a PQ stack entry.
1728          */
1729         epq = (evalPlanQual *) estate->es_evalPlanQual;
1730         rtsize = length(estate->es_range_table);
1731         endNode = true;
1732
1733         if (epq != NULL && epq->rti == 0)
1734         {
1735                 /* Top PQ stack entry is idle, so re-use it */
1736                 Assert(!(estate->es_useEvalPlan) &&
1737                            epq->estate.es_evalPlanQual == NULL);
1738                 epq->rti = rti;
1739                 endNode = false;
1740         }
1741
1742         /*
1743          * If this is request for another RTE - Ra, - then we have to check
1744          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1745          * updated again and we have to re-start old execution for Ra and
1746          * forget all what we done after Ra was suspended. Cool? -:))
1747          */
1748         if (epq != NULL && epq->rti != rti &&
1749                 epq->estate.es_evTuple[rti - 1] != NULL)
1750         {
1751                 do
1752                 {
1753                         evalPlanQual *oldepq;
1754
1755                         /* pop previous PlanQual from the stack */
1756                         epqstate = &(epq->estate);
1757                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1758                         Assert(oldepq->rti != 0);
1759                         /* stop execution */
1760                         ExecEndNode(epq->plan, NULL);
1761                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1762                         epqstate->es_tupleTable = NULL;
1763                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1764                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1765                         /* push current PQ to freePQ stack */
1766                         oldepq->free = epq;
1767                         epq = oldepq;
1768                         estate->es_evalPlanQual = (Pointer) epq;
1769                 } while (epq->rti != rti);
1770         }
1771
1772         /*
1773          * If we are requested for another RTE then we have to suspend
1774          * execution of current PlanQual and start execution for new one.
1775          */
1776         if (epq == NULL || epq->rti != rti)
1777         {
1778                 /* try to reuse plan used previously */
1779                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1780
1781                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1782                 {
1783                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1784                         newepq->free = NULL;
1785                         /*
1786                          * Each stack level has its own copy of the plan tree.  This
1787                          * is wasteful, but necessary as long as plan nodes point to
1788                          * exec state nodes rather than vice versa.  Note that copyfuncs.c
1789                          * doesn't attempt to copy the exec state nodes, which is a good
1790                          * thing in this situation.
1791                          */
1792                         newepq->plan = copyObject(estate->es_origPlan);
1793                         /*
1794                          * Init stack level's EState.  We share top level's copy of
1795                          * es_result_relations array and other non-changing status.
1796                          * We need our own tupletable, es_param_exec_vals, and other
1797                          * changeable state.
1798                          */
1799                         epqstate = &(newepq->estate);
1800                         memcpy(epqstate, estate, sizeof(EState));
1801                         epqstate->es_direction = ForwardScanDirection;
1802                         if (estate->es_origPlan->nParamExec > 0)
1803                                 epqstate->es_param_exec_vals = (ParamExecData *)
1804                                         palloc(estate->es_origPlan->nParamExec *
1805                                                    sizeof(ParamExecData));
1806                         epqstate->es_tupleTable = NULL;
1807                         epqstate->es_per_tuple_exprcontext = NULL;
1808                         /*
1809                          * Each epqstate must have its own es_evTupleNull state,
1810                          * but all the stack entries share es_evTuple state.  This
1811                          * allows sub-rechecks to inherit the value being examined by
1812                          * an outer recheck.
1813                          */
1814                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1815                         if (epq == NULL)
1816                         {
1817                                 /* first PQ stack entry */
1818                                 epqstate->es_evTuple = (HeapTuple *)
1819                                         palloc(rtsize * sizeof(HeapTuple));
1820                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1821                         }
1822                         else
1823                         {
1824                                 /* later stack entries share the same storage */
1825                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1826                         }
1827                 }
1828                 else
1829                 {
1830                         /* recycle previously used EState */
1831                         epqstate = &(newepq->estate);
1832                 }
1833                 /* push current PQ to the stack */
1834                 epqstate->es_evalPlanQual = (Pointer) epq;
1835                 epq = newepq;
1836                 estate->es_evalPlanQual = (Pointer) epq;
1837                 epq->rti = rti;
1838                 endNode = false;
1839         }
1840
1841         Assert(epq->rti == rti);
1842         epqstate = &(epq->estate);
1843
1844         /*
1845          * Ok - we're requested for the same RTE.  Unfortunately we still
1846          * have to end and restart execution of the plan, because ExecReScan
1847          * wouldn't ensure that upper plan nodes would reset themselves.  We
1848          * could make that work if insertion of the target tuple were integrated
1849          * with the Param mechanism somehow, so that the upper plan nodes know
1850          * that their children's outputs have changed.
1851          */
1852         if (endNode)
1853         {
1854                 /* stop execution */
1855                 ExecEndNode(epq->plan, NULL);
1856                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1857                 epqstate->es_tupleTable = NULL;
1858         }
1859
1860         /*
1861          * free old RTE' tuple, if any, and store target tuple where relation's
1862          * scan node will see it
1863          */
1864         if (epqstate->es_evTuple[rti - 1] != NULL)
1865                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1866         epqstate->es_evTuple[rti - 1] = copyTuple;
1867
1868         /*
1869          * Initialize for new recheck query; be careful to copy down state
1870          * that might have changed in top EState.
1871          */
1872         epqstate->es_result_relation_info = estate->es_result_relation_info;
1873         epqstate->es_junkFilter = estate->es_junkFilter;
1874         if (estate->es_origPlan->nParamExec > 0)
1875                 memset(epqstate->es_param_exec_vals, 0,
1876                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1877         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1878         epqstate->es_useEvalPlan = false;
1879         Assert(epqstate->es_tupleTable == NULL);
1880         epqstate->es_tupleTable =
1881                 ExecCreateTupleTable(estate->es_tupleTable->size);
1882
1883         ExecInitNode(epq->plan, epqstate, NULL);
1884
1885         return EvalPlanQualNext(estate);
1886 }
1887
1888 static TupleTableSlot *
1889 EvalPlanQualNext(EState *estate)
1890 {
1891         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1892         EState     *epqstate = &(epq->estate);
1893         evalPlanQual *oldepq;
1894         TupleTableSlot *slot;
1895
1896         Assert(epq->rti != 0);
1897
1898 lpqnext:;
1899         slot = ExecProcNode(epq->plan, NULL);
1900
1901         /*
1902          * No more tuples for this PQ. Continue previous one.
1903          */
1904         if (TupIsNull(slot))
1905         {
1906                 /* stop execution */
1907                 ExecEndNode(epq->plan, NULL);
1908                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1909                 epqstate->es_tupleTable = NULL;
1910                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1911                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1912                 /* pop old PQ from the stack */
1913                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1914                 if (oldepq == (evalPlanQual *) NULL)
1915                 {
1916                         epq->rti = 0;           /* this is the first (oldest) */
1917                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1918                         return (NULL);          /* continue Query execution   */
1919                 }
1920                 Assert(oldepq->rti != 0);
1921                 /* push current PQ to freePQ stack */
1922                 oldepq->free = epq;
1923                 epq = oldepq;
1924                 epqstate = &(epq->estate);
1925                 estate->es_evalPlanQual = (Pointer) epq;
1926                 goto lpqnext;
1927         }
1928
1929         return (slot);
1930 }
1931
1932 static void
1933 EndEvalPlanQual(EState *estate)
1934 {
1935         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1936         EState     *epqstate = &(epq->estate);
1937         evalPlanQual *oldepq;
1938
1939         if (epq->rti == 0)                      /* plans already shutdowned */
1940         {
1941                 Assert(epq->estate.es_evalPlanQual == NULL);
1942                 return;
1943         }
1944
1945         for (;;)
1946         {
1947                 /* stop execution */
1948                 ExecEndNode(epq->plan, NULL);
1949                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1950                 epqstate->es_tupleTable = NULL;
1951                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1952                 {
1953                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1954                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1955                 }
1956                 /* pop old PQ from the stack */
1957                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1958                 if (oldepq == (evalPlanQual *) NULL)
1959                 {
1960                         epq->rti = 0;           /* this is the first (oldest) */
1961                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1962                         break;
1963                 }
1964                 Assert(oldepq->rti != 0);
1965                 /* push current PQ to freePQ stack */
1966                 oldepq->free = epq;
1967                 epq = oldepq;
1968                 epqstate = &(epq->estate);
1969                 estate->es_evalPlanQual = (Pointer) epq;
1970         }
1971 }