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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.142 2001/05/27 20:48:51 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,
 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_ConstraintExprs = NULL;
 834         resultRelInfo->ri_junkFilter = NULL;
 835
 836         /*
 837          * If there are indices on the result relation, open them and save
 838          * descriptors in the result relation info, so that we can add new
 839          * index entries for the tuples we add/update.  We need not do this
 840          * for a DELETE, however, since deletion doesn't affect indexes.
 841          */
 842         if (resultRelationDesc->rd_rel->relhasindex &&
 843                 operation != CMD_DELETE)
 844                 ExecOpenIndices(resultRelInfo);
 845 }
 846
 847 /* ----------------------------------------------------------------
 848  *              EndPlan
 849  *
 850  *              Cleans up the query plan -- closes files and free up storages
 851  * ----------------------------------------------------------------
 852  */
 853 static void
 854 EndPlan(Plan *plan, EState *estate)
 855 {
 856         ResultRelInfo *resultRelInfo;
 857         int                     i;
 858         List       *l;
 859
 860         /*
 861          * shut down any PlanQual processing we were doing
 862          */
 863         if (estate->es_evalPlanQual != NULL)
 864                 EndEvalPlanQual(estate);
 865
 866         /*
 867          * shut down the node-type-specific query processing
 868          */
 869         ExecEndNode(plan, plan);
 870
 871         /*
 872          * destroy the executor "tuple" table.
 873          */
 874         ExecDropTupleTable(estate->es_tupleTable, true);
 875         estate->es_tupleTable = NULL;
 876
 877         /*
 878          * close the result relation(s) if any, but hold locks until xact
 879          * commit.      Also clean up junkfilters if present.
 880          */
 881         resultRelInfo = estate->es_result_relations;
 882         for (i = estate->es_num_result_relations; i > 0; i--)
 883         {
 884                 /* Close indices and then the relation itself */
 885                 ExecCloseIndices(resultRelInfo);
 886                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 887                 /* Delete the junkfilter if any */
 888                 if (resultRelInfo->ri_junkFilter != NULL)
 889                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 890                 resultRelInfo++;
 891         }
 892
 893         /*
 894          * close the "into" relation if necessary, again keeping lock
 895          */
 896         if (estate->es_into_relation_descriptor != NULL)
 897                 heap_close(estate->es_into_relation_descriptor, NoLock);
 898
 899         /*
 900          * There might be a junkfilter without a result relation.
 901          */
 902         if (estate->es_num_result_relations == 0 &&
 903                 estate->es_junkFilter != NULL)
 904         {
 905                 ExecFreeJunkFilter(estate->es_junkFilter);
 906                 estate->es_junkFilter = NULL;
 907         }
 908
 909         /*
 910          * close any relations selected FOR UPDATE, again keeping locks
 911          */
 912         foreach(l, estate->es_rowMark)
 913         {
 914                 execRowMark *erm = lfirst(l);
 915
 916                 heap_close(erm->relation, NoLock);
 917         }
 918 }
 919
 920 /* ----------------------------------------------------------------
 921  *              ExecutePlan
 922  *
 923  *              processes the query plan to retrieve 'numberTuples' tuples in the
 924  *              direction specified.
 925  *              Retrieves all tuples if tupleCount is 0
 926  *
 927  *              result is either a slot containing the last tuple in the case
 928  *              of a RETRIEVE or NULL otherwise.
 929  *
 930  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 931  * user can see it
 932  * ----------------------------------------------------------------
 933  */
 934 static TupleTableSlot *
 935 ExecutePlan(EState *estate,
 936                         Plan *plan,
 937                         CmdType operation,
 938                         long numberTuples,
 939                         ScanDirection direction,
 940                         DestReceiver *destfunc)
 941 {
 942         JunkFilter *junkfilter;
 943         TupleTableSlot *slot;
 944         ItemPointer tupleid = NULL;
 945         ItemPointerData tuple_ctid;
 946         long            current_tuple_count;
 947         TupleTableSlot *result;
 948
 949         /*
 950          * initialize local variables
 951          */
 952         slot = NULL;
 953         current_tuple_count = 0;
 954         result = NULL;
 955
 956         /*
 957          * Set the direction.
 958          */
 959         estate->es_direction = direction;
 960
 961         /*
 962          * Loop until we've processed the proper number of tuples from the
 963          * plan.
 964          */
 965
 966         for (;;)
 967         {
 968                 /* Reset the per-output-tuple exprcontext */
 969                 ResetPerTupleExprContext(estate);
 970
 971                 /*
 972                  * Execute the plan and obtain a tuple
 973                  */
 974                 /* at the top level, the parent of a plan (2nd arg) is itself */
 975 lnext:  ;
 976                 if (estate->es_useEvalPlan)
 977                 {
 978                         slot = EvalPlanQualNext(estate);
 979                         if (TupIsNull(slot))
 980                                 slot = ExecProcNode(plan, plan);
 981                 }
 982                 else
 983                         slot = ExecProcNode(plan, plan);
 984
 985                 /*
 986                  * if the tuple is null, then we assume there is nothing more to
 987                  * process so we just return null...
 988                  */
 989                 if (TupIsNull(slot))
 990                 {
 991                         result = NULL;
 992                         break;
 993                 }
 994
 995                 /*
 996                  * if we have a junk filter, then project a new tuple with the
 997                  * junk removed.
 998                  *
 999                  * Store this new "clean" tuple in the junkfilter's resultSlot.
1000                  * (Formerly, we stored it back over the "dirty" tuple, which is
1001                  * WRONG because that tuple slot has the wrong descriptor.)
1002                  *
1003                  * Also, extract all the junk information we need.
1004                  */
1005                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
1006                 {
1007                         Datum           datum;
1008                         HeapTuple       newTuple;
1009                         bool            isNull;
1010
1011                         /*
1012                          * extract the 'ctid' junk attribute.
1013                          */
1014                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1015                         {
1016                                 if (!ExecGetJunkAttribute(junkfilter,
1017                                                                                   slot,
1018                                                                                   "ctid",
1019                                                                                   &datum,
1020                                                                                   &isNull))
1021                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1022
1023                                 /* shouldn't ever get a null result... */
1024                                 if (isNull)
1025                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1026
1027                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1028                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1029                                                                                  * ctid!! */
1030                                 tupleid = &tuple_ctid;
1031                         }
1032                         else if (estate->es_rowMark != NIL)
1033                         {
1034                                 List       *l;
1035
1036                 lmark:  ;
1037                                 foreach(l, estate->es_rowMark)
1038                                 {
1039                                         execRowMark *erm = lfirst(l);
1040                                         Buffer          buffer;
1041                                         HeapTupleData tuple;
1042                                         TupleTableSlot *newSlot;
1043                                         int                     test;
1044
1045                                         if (!ExecGetJunkAttribute(junkfilter,
1046                                                                                           slot,
1047                                                                                           erm->resname,
1048                                                                                           &datum,
1049                                                                                           &isNull))
1050                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1051                                                          erm->resname);
1052
1053                                         /* shouldn't ever get a null result... */
1054                                         if (isNull)
1055                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1056                                                          erm->resname);
1057
1058                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1059                                         test = heap_mark4update(erm->relation, &tuple, &buffer);
1060                                         ReleaseBuffer(buffer);
1061                                         switch (test)
1062                                         {
1063                                                 case HeapTupleSelfUpdated:
1064                                                 case HeapTupleMayBeUpdated:
1065                                                         break;
1066
1067                                                 case HeapTupleUpdated:
1068                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1069                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1070                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1071                                                                   (ItemPointer) DatumGetPointer(datum))))
1072                                                         {
1073                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1074                                                                 if (!(TupIsNull(newSlot)))
1075                                                                 {
1076                                                                         slot = newSlot;
1077                                                                         estate->es_useEvalPlan = true;
1078                                                                         goto lmark;
1079                                                                 }
1080                                                         }
1081
1082                                                         /*
1083                                                          * if tuple was deleted or PlanQual failed for
1084                                                          * updated tuple - we must not return this
1085                                                          * tuple!
1086                                                          */
1087                                                         goto lnext;
1088
1089                                                 default:
1090                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1091                                                         return (NULL);
1092                                         }
1093                                 }
1094                         }
1095
1096                         /*
1097                          * Finally create a new "clean" tuple with all junk attributes
1098                          * removed
1099                          */
1100                         newTuple = ExecRemoveJunk(junkfilter, slot);
1101
1102                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1103                                                                   junkfilter->jf_resultSlot, /* dest slot */
1104                                                                   InvalidBuffer,                /* this tuple has no
1105                                                                                                                  * buffer */
1106                                                                   true);                /* tuple should be pfreed */
1107                 }                                               /* if (junkfilter... */
1108
1109                 /*
1110                  * now that we have a tuple, do the appropriate thing with it..
1111                  * either return it to the user, add it to a relation someplace,
1112                  * delete it from a relation, or modify some of its attributes.
1113                  */
1114
1115                 switch (operation)
1116                 {
1117                         case CMD_SELECT:
1118                                 ExecRetrieve(slot,              /* slot containing tuple */
1119                                                          destfunc,      /* destination's tuple-receiver
1120                                                                                  * obj */
1121                                                          estate);       /* */
1122                                 result = slot;
1123                                 break;
1124
1125                         case CMD_INSERT:
1126                                 ExecAppend(slot, tupleid, estate);
1127                                 result = NULL;
1128                                 break;
1129
1130                         case CMD_DELETE:
1131                                 ExecDelete(slot, tupleid, estate);
1132                                 result = NULL;
1133                                 break;
1134
1135                         case CMD_UPDATE:
1136                                 ExecReplace(slot, tupleid, estate);
1137                                 result = NULL;
1138                                 break;
1139
1140                         default:
1141                                 elog(DEBUG, "ExecutePlan: unknown operation in queryDesc");
1142                                 result = NULL;
1143                                 break;
1144                 }
1145
1146                 /*
1147                  * check our tuple count.. if we've processed the proper number
1148                  * then quit, else loop again and process more tuples..
1149                  */
1150                 current_tuple_count++;
1151                 if (numberTuples == current_tuple_count)
1152                         break;
1153         }
1154
1155         /*
1156          * here, result is either a slot containing a tuple in the case of a
1157          * RETRIEVE or NULL otherwise.
1158          */
1159         return result;
1160 }
1161
1162 /* ----------------------------------------------------------------
1163  *              ExecRetrieve
1164  *
1165  *              RETRIEVEs are easy.. we just pass the tuple to the appropriate
1166  *              print function.  The only complexity is when we do a
1167  *              "retrieve into", in which case we insert the tuple into
1168  *              the appropriate relation (note: this is a newly created relation
1169  *              so we don't need to worry about indices or locks.)
1170  * ----------------------------------------------------------------
1171  */
1172 static void
1173 ExecRetrieve(TupleTableSlot *slot,
1174                          DestReceiver *destfunc,
1175                          EState *estate)
1176 {
1177         HeapTuple       tuple;
1178         TupleDesc       attrtype;
1179
1180         /*
1181          * get the heap tuple out of the tuple table slot
1182          */
1183         tuple = slot->val;
1184         attrtype = slot->ttc_tupleDescriptor;
1185
1186         /*
1187          * insert the tuple into the "into relation"
1188          */
1189         if (estate->es_into_relation_descriptor != NULL)
1190         {
1191                 heap_insert(estate->es_into_relation_descriptor, tuple);
1192                 IncrAppended();
1193         }
1194
1195         /*
1196          * send the tuple to the front end (or the screen)
1197          */
1198         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1199         IncrRetrieved();
1200         (estate->es_processed)++;
1201 }
1202
1203 /* ----------------------------------------------------------------
1204  *              ExecAppend
1205  *
1206  *              APPENDs are trickier.. we have to insert the tuple into
1207  *              the base relation and insert appropriate tuples into the
1208  *              index relations.
1209  * ----------------------------------------------------------------
1210  */
1211
1212 static void
1213 ExecAppend(TupleTableSlot *slot,
1214                    ItemPointer tupleid,
1215                    EState *estate)
1216 {
1217         HeapTuple       tuple;
1218         ResultRelInfo *resultRelInfo;
1219         Relation        resultRelationDesc;
1220         int                     numIndices;
1221         Oid                     newId;
1222
1223         /*
1224          * get the heap tuple out of the tuple table slot
1225          */
1226         tuple = slot->val;
1227
1228         /*
1229          * get information on the (current) result relation
1230          */
1231         resultRelInfo = estate->es_result_relation_info;
1232         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1233
1234         /* BEFORE ROW INSERT Triggers */
1235         if (resultRelationDesc->trigdesc &&
1236         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1237         {
1238                 HeapTuple       newtuple;
1239
1240                 newtuple = ExecBRInsertTriggers(estate, resultRelationDesc, tuple);
1241
1242                 if (newtuple == NULL)   /* "do nothing" */
1243                         return;
1244
1245                 if (newtuple != tuple)  /* modified by Trigger(s) */
1246                 {
1247
1248                         /*
1249                          * Insert modified tuple into tuple table slot, replacing the
1250                          * original.  We assume that it was allocated in per-tuple
1251                          * memory context, and therefore will go away by itself. The
1252                          * tuple table slot should not try to clear it.
1253                          */
1254                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1255                         tuple = newtuple;
1256                 }
1257         }
1258
1259         /*
1260          * Check the constraints of the tuple
1261          */
1262         if (resultRelationDesc->rd_att->constr)
1263                 ExecConstraints("ExecAppend", resultRelInfo, slot, estate);
1264
1265         /*
1266          * insert the tuple
1267          */
1268         newId = heap_insert(resultRelationDesc, tuple);
1269
1270         IncrAppended();
1271         (estate->es_processed)++;
1272         estate->es_lastoid = newId;
1273
1274         /*
1275          * process indices
1276          *
1277          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1278          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1279          * field.
1280          */
1281         numIndices = resultRelInfo->ri_NumIndices;
1282         if (numIndices > 0)
1283                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1284
1285         /* AFTER ROW INSERT Triggers */
1286         if (resultRelationDesc->trigdesc)
1287                 ExecARInsertTriggers(estate, resultRelationDesc, tuple);
1288 }
1289
1290 /* ----------------------------------------------------------------
1291  *              ExecDelete
1292  *
1293  *              DELETE is like append, we delete the tuple and its
1294  *              index tuples.
1295  * ----------------------------------------------------------------
1296  */
1297 static void
1298 ExecDelete(TupleTableSlot *slot,
1299                    ItemPointer tupleid,
1300                    EState *estate)
1301 {
1302         ResultRelInfo *resultRelInfo;
1303         Relation        resultRelationDesc;
1304         ItemPointerData ctid;
1305         int                     result;
1306
1307         /*
1308          * get information on the (current) result relation
1309          */
1310         resultRelInfo = estate->es_result_relation_info;
1311         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1312
1313         /* BEFORE ROW DELETE Triggers */
1314         if (resultRelationDesc->trigdesc &&
1315         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1316         {
1317                 bool            dodelete;
1318
1319                 dodelete = ExecBRDeleteTriggers(estate, tupleid);
1320
1321                 if (!dodelete)                  /* "do nothing" */
1322                         return;
1323         }
1324
1325         /*
1326          * delete the tuple
1327          */
1328 ldelete:;
1329         result = heap_delete(resultRelationDesc, tupleid, &ctid);
1330         switch (result)
1331         {
1332                 case HeapTupleSelfUpdated:
1333                         return;
1334
1335                 case HeapTupleMayBeUpdated:
1336                         break;
1337
1338                 case HeapTupleUpdated:
1339                         if (XactIsoLevel == XACT_SERIALIZABLE)
1340                                 elog(ERROR, "Can't serialize access due to concurrent update");
1341                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1342                         {
1343                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1344                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1345
1346                                 if (!TupIsNull(epqslot))
1347                                 {
1348                                         *tupleid = ctid;
1349                                         goto ldelete;
1350                                 }
1351                         }
1352                         /* tuple already deleted; nothing to do */
1353                         return;
1354
1355                 default:
1356                         elog(ERROR, "Unknown status %u from heap_delete", result);
1357                         return;
1358         }
1359
1360         IncrDeleted();
1361         (estate->es_processed)++;
1362
1363         /*
1364          * Note: Normally one would think that we have to delete index tuples
1365          * associated with the heap tuple now..
1366          *
1367          * ... but in POSTGRES, we have no need to do this because the vacuum
1368          * daemon automatically opens an index scan and deletes index tuples
1369          * when it finds deleted heap tuples. -cim 9/27/89
1370          */
1371
1372         /* AFTER ROW DELETE Triggers */
1373         if (resultRelationDesc->trigdesc)
1374                 ExecARDeleteTriggers(estate, tupleid);
1375 }
1376
1377 /* ----------------------------------------------------------------
1378  *              ExecReplace
1379  *
1380  *              note: we can't run replace queries with transactions
1381  *              off because replaces are actually appends and our
1382  *              scan will mistakenly loop forever, replacing the tuple
1383  *              it just appended..      This should be fixed but until it
1384  *              is, we don't want to get stuck in an infinite loop
1385  *              which corrupts your database..
1386  * ----------------------------------------------------------------
1387  */
1388 static void
1389 ExecReplace(TupleTableSlot *slot,
1390                         ItemPointer tupleid,
1391                         EState *estate)
1392 {
1393         HeapTuple       tuple;
1394         ResultRelInfo *resultRelInfo;
1395         Relation        resultRelationDesc;
1396         ItemPointerData ctid;
1397         int                     result;
1398         int                     numIndices;
1399
1400         /*
1401          * abort the operation if not running transactions
1402          */
1403         if (IsBootstrapProcessingMode())
1404         {
1405                 elog(NOTICE, "ExecReplace: replace can't run without transactions");
1406                 return;
1407         }
1408
1409         /*
1410          * get the heap tuple out of the tuple table slot
1411          */
1412         tuple = slot->val;
1413
1414         /*
1415          * get information on the (current) result relation
1416          */
1417         resultRelInfo = estate->es_result_relation_info;
1418         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1419
1420         /* BEFORE ROW UPDATE Triggers */
1421         if (resultRelationDesc->trigdesc &&
1422         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1423         {
1424                 HeapTuple       newtuple;
1425
1426                 newtuple = ExecBRUpdateTriggers(estate, tupleid, tuple);
1427
1428                 if (newtuple == NULL)   /* "do nothing" */
1429                         return;
1430
1431                 if (newtuple != tuple)  /* modified by Trigger(s) */
1432                 {
1433
1434                         /*
1435                          * Insert modified tuple into tuple table slot, replacing the
1436                          * original.  We assume that it was allocated in per-tuple
1437                          * memory context, and therefore will go away by itself. The
1438                          * tuple table slot should not try to clear it.
1439                          */
1440                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1441                         tuple = newtuple;
1442                 }
1443         }
1444
1445         /*
1446          * Check the constraints of the tuple
1447          *
1448          * If we generate a new candidate tuple after EvalPlanQual testing,
1449          * we must loop back here and recheck constraints.  (We don't need to
1450          * redo triggers, however.  If there are any BEFORE triggers then
1451          * trigger.c will have done mark4update to lock the correct tuple,
1452          * so there's no need to do them again.)
1453          */
1454 lreplace:;
1455         if (resultRelationDesc->rd_att->constr)
1456                 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1457
1458         /*
1459          * replace the heap tuple
1460          */
1461         result = heap_update(resultRelationDesc, tupleid, tuple, &ctid);
1462         switch (result)
1463         {
1464                 case HeapTupleSelfUpdated:
1465                         return;
1466
1467                 case HeapTupleMayBeUpdated:
1468                         break;
1469
1470                 case HeapTupleUpdated:
1471                         if (XactIsoLevel == XACT_SERIALIZABLE)
1472                                 elog(ERROR, "Can't serialize access due to concurrent update");
1473                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1474                         {
1475                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1476                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1477
1478                                 if (!TupIsNull(epqslot))
1479                                 {
1480                                         *tupleid = ctid;
1481                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1482                                         slot = ExecStoreTuple(tuple,
1483                                                                                   estate->es_junkFilter->jf_resultSlot,
1484                                                                                   InvalidBuffer, true);
1485                                         goto lreplace;
1486                                 }
1487                         }
1488                         /* tuple already deleted; nothing to do */
1489                         return;
1490
1491                 default:
1492                         elog(ERROR, "Unknown status %u from heap_update", result);
1493                         return;
1494         }
1495
1496         IncrReplaced();
1497         (estate->es_processed)++;
1498
1499         /*
1500          * Note: instead of having to update the old index tuples associated
1501          * with the heap tuple, all we do is form and insert new index tuples.
1502          * This is because replaces are actually deletes and inserts and index
1503          * tuple deletion is done automagically by the vacuum daemon. All we
1504          * do is insert new index tuples.  -cim 9/27/89
1505          */
1506
1507         /*
1508          * process indices
1509          *
1510          * heap_update updates a tuple in the base relation by invalidating it
1511          * and then appending a new tuple to the relation.      As a side effect,
1512          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1513          * field.  So we now insert index tuples using the new tupleid stored
1514          * there.
1515          */
1516
1517         numIndices = resultRelInfo->ri_NumIndices;
1518         if (numIndices > 0)
1519                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, true);
1520
1521         /* AFTER ROW UPDATE Triggers */
1522         if (resultRelationDesc->trigdesc)
1523                 ExecARUpdateTriggers(estate, tupleid, tuple);
1524 }
1525
1526 static char *
1527 ExecRelCheck(ResultRelInfo *resultRelInfo,
1528                          TupleTableSlot *slot, EState *estate)
1529 {
1530         Relation        rel = resultRelInfo->ri_RelationDesc;
1531         int                     ncheck = rel->rd_att->constr->num_check;
1532         ConstrCheck *check = rel->rd_att->constr->check;
1533         ExprContext *econtext;
1534         MemoryContext oldContext;
1535         List       *qual;
1536         int                     i;
1537
1538         /*
1539          * If first time through for this result relation, build expression
1540          * nodetrees for rel's constraint expressions.  Keep them in the
1541          * per-query memory context so they'll survive throughout the query.
1542          */
1543         if (resultRelInfo->ri_ConstraintExprs == NULL)
1544         {
1545                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1546                 resultRelInfo->ri_ConstraintExprs =
1547                         (List **) palloc(ncheck * sizeof(List *));
1548                 for (i = 0; i < ncheck; i++)
1549                 {
1550                         qual = (List *) stringToNode(check[i].ccbin);
1551                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1552                 }
1553                 MemoryContextSwitchTo(oldContext);
1554         }
1555
1556         /*
1557          * We will use the EState's per-tuple context for evaluating
1558          * constraint expressions (creating it if it's not already there).
1559          */
1560         econtext = GetPerTupleExprContext(estate);
1561
1562         /* Arrange for econtext's scan tuple to be the tuple under test */
1563         econtext->ecxt_scantuple = slot;
1564
1565         /* And evaluate the constraints */
1566         for (i = 0; i < ncheck; i++)
1567         {
1568                 qual = resultRelInfo->ri_ConstraintExprs[i];
1569
1570                 /*
1571                  * NOTE: SQL92 specifies that a NULL result from a constraint
1572                  * expression is not to be treated as a failure.  Therefore, tell
1573                  * ExecQual to return TRUE for NULL.
1574                  */
1575                 if (!ExecQual(qual, econtext, true))
1576                         return check[i].ccname;
1577         }
1578
1579         /* NULL result means no error */
1580         return (char *) NULL;
1581 }
1582
1583 void
1584 ExecConstraints(char *caller, ResultRelInfo *resultRelInfo,
1585                                 TupleTableSlot *slot, EState *estate)
1586 {
1587         Relation        rel = resultRelInfo->ri_RelationDesc;
1588         HeapTuple       tuple = slot->val;
1589         TupleConstr *constr = rel->rd_att->constr;
1590
1591         Assert(constr);
1592
1593         if (constr->has_not_null)
1594         {
1595                 int                     natts = rel->rd_att->natts;
1596                 int                     attrChk;
1597
1598                 for (attrChk = 1; attrChk <= natts; attrChk++)
1599                 {
1600                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1601                                 heap_attisnull(tuple, attrChk))
1602                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1603                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1604                 }
1605         }
1606
1607         if (constr->num_check > 0)
1608         {
1609                 char       *failed;
1610
1611                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1612                         elog(ERROR, "%s: rejected due to CHECK constraint %s",
1613                                  caller, failed);
1614         }
1615 }
1616
1617 /*
1618  * Check a modified tuple to see if we want to process its updated version
1619  * under READ COMMITTED rules.
1620  *
1621  * See backend/executor/README for some info about how this works.
1622  */
1623 TupleTableSlot *
1624 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1625 {
1626         evalPlanQual *epq;
1627         EState     *epqstate;
1628         Relation        relation;
1629         HeapTupleData tuple;
1630         HeapTuple       copyTuple = NULL;
1631         int                     rtsize;
1632         bool            endNode;
1633
1634         Assert(rti != 0);
1635
1636         /*
1637          * find relation containing target tuple
1638          */
1639         if (estate->es_result_relation_info != NULL &&
1640                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1641         {
1642                 relation = estate->es_result_relation_info->ri_RelationDesc;
1643         }
1644         else
1645         {
1646                 List       *l;
1647
1648                 relation = NULL;
1649                 foreach(l, estate->es_rowMark)
1650                 {
1651                         if (((execRowMark *) lfirst(l))->rti == rti)
1652                         {
1653                                 relation = ((execRowMark *) lfirst(l))->relation;
1654                                 break;
1655                         }
1656                 }
1657                 if (relation == NULL)
1658                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1659         }
1660
1661         /*
1662          * fetch tid tuple
1663          *
1664          * Loop here to deal with updated or busy tuples
1665          */
1666         tuple.t_self = *tid;
1667         for (;;)
1668         {
1669                 Buffer          buffer;
1670
1671                 heap_fetch(relation, SnapshotDirty, &tuple, &buffer);
1672                 if (tuple.t_data != NULL)
1673                 {
1674                         TransactionId xwait = SnapshotDirty->xmax;
1675
1676                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1677                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1678
1679                         /*
1680                          * If tuple is being updated by other transaction then we have
1681                          * to wait for its commit/abort.
1682                          */
1683                         if (TransactionIdIsValid(xwait))
1684                         {
1685                                 ReleaseBuffer(buffer);
1686                                 XactLockTableWait(xwait);
1687                                 continue;
1688                         }
1689
1690                         /*
1691                          * We got tuple - now copy it for use by recheck query.
1692                          */
1693                         copyTuple = heap_copytuple(&tuple);
1694                         ReleaseBuffer(buffer);
1695                         break;
1696                 }
1697
1698                 /*
1699                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1700                  * Note that it's possible to get invalid SnapshotDirty->tid if
1701                  * tuple updated by this transaction. Have we to check this ?
1702                  */
1703                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1704                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1705                 {
1706                         /* updated, so look at the updated copy */
1707                         tuple.t_self = SnapshotDirty->tid;
1708                         continue;
1709                 }
1710
1711                 /*
1712                  * Deleted or updated by this transaction; forget it.
1713                  */
1714                 return NULL;
1715         }
1716
1717         /*
1718          * For UPDATE/DELETE we have to return tid of actual row we're
1719          * executing PQ for.
1720          */
1721         *tid = tuple.t_self;
1722
1723         /*
1724          * Need to run a recheck subquery.  Find or create a PQ stack entry.
1725          */
1726         epq = (evalPlanQual *) estate->es_evalPlanQual;
1727         rtsize = length(estate->es_range_table);
1728         endNode = true;
1729
1730         if (epq != NULL && epq->rti == 0)
1731         {
1732                 /* Top PQ stack entry is idle, so re-use it */
1733                 Assert(!(estate->es_useEvalPlan) &&
1734                            epq->estate.es_evalPlanQual == NULL);
1735                 epq->rti = rti;
1736                 endNode = false;
1737         }
1738
1739         /*
1740          * If this is request for another RTE - Ra, - then we have to check
1741          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1742          * updated again and we have to re-start old execution for Ra and
1743          * forget all what we done after Ra was suspended. Cool? -:))
1744          */
1745         if (epq != NULL && epq->rti != rti &&
1746                 epq->estate.es_evTuple[rti - 1] != NULL)
1747         {
1748                 do
1749                 {
1750                         evalPlanQual *oldepq;
1751
1752                         /* pop previous PlanQual from the stack */
1753                         epqstate = &(epq->estate);
1754                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1755                         Assert(oldepq->rti != 0);
1756                         /* stop execution */
1757                         ExecEndNode(epq->plan, epq->plan);
1758                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1759                         epqstate->es_tupleTable = NULL;
1760                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1761                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1762                         /* push current PQ to freePQ stack */
1763                         oldepq->free = epq;
1764                         epq = oldepq;
1765                         estate->es_evalPlanQual = (Pointer) epq;
1766                 } while (epq->rti != rti);
1767         }
1768
1769         /*
1770          * If we are requested for another RTE then we have to suspend
1771          * execution of current PlanQual and start execution for new one.
1772          */
1773         if (epq == NULL || epq->rti != rti)
1774         {
1775                 /* try to reuse plan used previously */
1776                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1777
1778                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1779                 {
1780                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1781                         newepq->free = NULL;
1782                         /*
1783                          * Each stack level has its own copy of the plan tree.  This
1784                          * is wasteful, but necessary as long as plan nodes point to
1785                          * exec state nodes rather than vice versa.  Note that copyfuncs.c
1786                          * doesn't attempt to copy the exec state nodes, which is a good
1787                          * thing in this situation.
1788                          */
1789                         newepq->plan = copyObject(estate->es_origPlan);
1790                         /*
1791                          * Init stack level's EState.  We share top level's copy of
1792                          * es_result_relations array and other non-changing status.
1793                          * We need our own tupletable, es_param_exec_vals, and other
1794                          * changeable state.
1795                          */
1796                         epqstate = &(newepq->estate);
1797                         memcpy(epqstate, estate, sizeof(EState));
1798                         epqstate->es_direction = ForwardScanDirection;
1799                         if (estate->es_origPlan->nParamExec > 0)
1800                                 epqstate->es_param_exec_vals = (ParamExecData *)
1801                                         palloc(estate->es_origPlan->nParamExec *
1802                                                    sizeof(ParamExecData));
1803                         epqstate->es_tupleTable = NULL;
1804                         epqstate->es_per_tuple_exprcontext = NULL;
1805                         /*
1806                          * Each epqstate must have its own es_evTupleNull state,
1807                          * but all the stack entries share es_evTuple state.  This
1808                          * allows sub-rechecks to inherit the value being examined by
1809                          * an outer recheck.
1810                          */
1811                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1812                         if (epq == NULL)
1813                         {
1814                                 /* first PQ stack entry */
1815                                 epqstate->es_evTuple = (HeapTuple *)
1816                                         palloc(rtsize * sizeof(HeapTuple));
1817                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1818                         }
1819                         else
1820                         {
1821                                 /* later stack entries share the same storage */
1822                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1823                         }
1824                 }
1825                 else
1826                 {
1827                         /* recycle previously used EState */
1828                         epqstate = &(newepq->estate);
1829                 }
1830                 /* push current PQ to the stack */
1831                 epqstate->es_evalPlanQual = (Pointer) epq;
1832                 epq = newepq;
1833                 estate->es_evalPlanQual = (Pointer) epq;
1834                 epq->rti = rti;
1835                 endNode = false;
1836         }
1837
1838         Assert(epq->rti == rti);
1839         epqstate = &(epq->estate);
1840
1841         /*
1842          * Ok - we're requested for the same RTE.  Unfortunately we still
1843          * have to end and restart execution of the plan, because ExecReScan
1844          * wouldn't ensure that upper plan nodes would reset themselves.  We
1845          * could make that work if insertion of the target tuple were integrated
1846          * with the Param mechanism somehow, so that the upper plan nodes know
1847          * that their children's outputs have changed.
1848          */
1849         if (endNode)
1850         {
1851                 /* stop execution */
1852                 ExecEndNode(epq->plan, epq->plan);
1853                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1854                 epqstate->es_tupleTable = NULL;
1855         }
1856
1857         /*
1858          * free old RTE' tuple, if any, and store target tuple where relation's
1859          * scan node will see it
1860          */
1861         if (epqstate->es_evTuple[rti - 1] != NULL)
1862                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1863         epqstate->es_evTuple[rti - 1] = copyTuple;
1864
1865         /*
1866          * Initialize for new recheck query; be careful to copy down state
1867          * that might have changed in top EState.
1868          */
1869         epqstate->es_result_relation_info = estate->es_result_relation_info;
1870         epqstate->es_junkFilter = estate->es_junkFilter;
1871         if (estate->es_origPlan->nParamExec > 0)
1872                 memset(epqstate->es_param_exec_vals, 0,
1873                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1874         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1875         epqstate->es_useEvalPlan = false;
1876         Assert(epqstate->es_tupleTable == NULL);
1877         epqstate->es_tupleTable =
1878                 ExecCreateTupleTable(estate->es_tupleTable->size);
1879
1880         ExecInitNode(epq->plan, epqstate, NULL);
1881
1882         return EvalPlanQualNext(estate);
1883 }
1884
1885 static TupleTableSlot *
1886 EvalPlanQualNext(EState *estate)
1887 {
1888         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1889         EState     *epqstate = &(epq->estate);
1890         evalPlanQual *oldepq;
1891         TupleTableSlot *slot;
1892
1893         Assert(epq->rti != 0);
1894
1895 lpqnext:;
1896         slot = ExecProcNode(epq->plan, epq->plan);
1897
1898         /*
1899          * No more tuples for this PQ. Continue previous one.
1900          */
1901         if (TupIsNull(slot))
1902         {
1903                 /* stop execution */
1904                 ExecEndNode(epq->plan, epq->plan);
1905                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1906                 epqstate->es_tupleTable = NULL;
1907                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1908                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1909                 /* pop old PQ from the stack */
1910                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1911                 if (oldepq == (evalPlanQual *) NULL)
1912                 {
1913                         epq->rti = 0;           /* this is the first (oldest) */
1914                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1915                         return (NULL);          /* continue Query execution   */
1916                 }
1917                 Assert(oldepq->rti != 0);
1918                 /* push current PQ to freePQ stack */
1919                 oldepq->free = epq;
1920                 epq = oldepq;
1921                 epqstate = &(epq->estate);
1922                 estate->es_evalPlanQual = (Pointer) epq;
1923                 goto lpqnext;
1924         }
1925
1926         return (slot);
1927 }
1928
1929 static void
1930 EndEvalPlanQual(EState *estate)
1931 {
1932         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1933         EState     *epqstate = &(epq->estate);
1934         evalPlanQual *oldepq;
1935
1936         if (epq->rti == 0)                      /* plans already shutdowned */
1937         {
1938                 Assert(epq->estate.es_evalPlanQual == NULL);
1939                 return;
1940         }
1941
1942         for (;;)
1943         {
1944                 /* stop execution */
1945                 ExecEndNode(epq->plan, epq->plan);
1946                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1947                 epqstate->es_tupleTable = NULL;
1948                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1949                 {
1950                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1951                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1952                 }
1953                 /* pop old PQ from the stack */
1954                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1955                 if (oldepq == (evalPlanQual *) NULL)
1956                 {
1957                         epq->rti = 0;           /* this is the first (oldest) */
1958                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1959                         break;
1960                 }
1961                 Assert(oldepq->rti != 0);
1962                 /* push current PQ to freePQ stack */
1963                 oldepq->free = epq;
1964                 epq = oldepq;
1965                 epqstate = &(epq->estate);
1966                 estate->es_evalPlanQual = (Pointer) epq;
1967         }
1968 }