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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.140 2001/05/15 00:33:36 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_RD);
 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                                 /* Accept either APPEND or WRITE access for this */
 441                                 aclcheck_result = CHECK(ACL_AP);
 442                                 if (aclcheck_result != ACLCHECK_OK)
 443                                         aclcheck_result = CHECK(ACL_WR);
 444                                 break;
 445                         case CMD_SELECT:
 446                         case CMD_DELETE:
 447                         case CMD_UPDATE:
 448                                 aclcheck_result = CHECK(ACL_WR);
 449                                 break;
 450                         default:
 451                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 452                                          operation);
 453                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 454                                 break;
 455                 }
 456                 if (aclcheck_result != ACLCHECK_OK)
 457                         elog(ERROR, "%s: %s",
 458                                  relName, aclcheck_error_strings[aclcheck_result]);
 459         }
 460 }
 461
 462
 463 /* ===============================================================
 464  * ===============================================================
 465                                                  static routines follow
 466  * ===============================================================
 467  * ===============================================================
 468  */
 469
 470 typedef struct execRowMark
 471 {
 472         Relation        relation;
 473         Index           rti;
 474         char            resname[32];
 475 } execRowMark;
 476
 477 typedef struct evalPlanQual
 478 {
 479         Plan       *plan;
 480         Index           rti;
 481         EState          estate;
 482         struct evalPlanQual *free;
 483 } evalPlanQual;
 484
 485 /* ----------------------------------------------------------------
 486  *              InitPlan
 487  *
 488  *              Initializes the query plan: open files, allocate storage
 489  *              and start up the rule manager
 490  * ----------------------------------------------------------------
 491  */
 492 static TupleDesc
 493 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 494 {
 495         List       *rangeTable;
 496         Relation        intoRelationDesc;
 497         TupleDesc       tupType;
 498
 499         /*
 500          * Do permissions checks.
 501          */
 502         ExecCheckQueryPerms(operation, parseTree, plan);
 503
 504         /*
 505          * get information from query descriptor
 506          */
 507         rangeTable = parseTree->rtable;
 508
 509         /*
 510          * initialize the node's execution state
 511          */
 512         estate->es_range_table = rangeTable;
 513
 514         /*
 515          * if there is a result relation, initialize result relation stuff
 516          */
 517         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 518         {
 519                 List       *resultRelations = parseTree->resultRelations;
 520                 int                     numResultRelations;
 521                 ResultRelInfo *resultRelInfos;
 522
 523                 if (resultRelations != NIL)
 524                 {
 525
 526                         /*
 527                          * Multiple result relations (due to inheritance)
 528                          * parseTree->resultRelations identifies them all
 529                          */
 530                         ResultRelInfo *resultRelInfo;
 531
 532                         numResultRelations = length(resultRelations);
 533                         resultRelInfos = (ResultRelInfo *)
 534                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 535                         resultRelInfo = resultRelInfos;
 536                         while (resultRelations != NIL)
 537                         {
 538                                 initResultRelInfo(resultRelInfo,
 539                                                                   lfirsti(resultRelations),
 540                                                                   rangeTable,
 541                                                                   operation);
 542                                 resultRelInfo++;
 543                                 resultRelations = lnext(resultRelations);
 544                         }
 545                 }
 546                 else
 547                 {
 548
 549                         /*
 550                          * Single result relation identified by
 551                          * parseTree->resultRelation
 552                          */
 553                         numResultRelations = 1;
 554                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 555                         initResultRelInfo(resultRelInfos,
 556                                                           parseTree->resultRelation,
 557                                                           rangeTable,
 558                                                           operation);
 559                 }
 560
 561                 estate->es_result_relations = resultRelInfos;
 562                 estate->es_num_result_relations = numResultRelations;
 563                 /* Initialize to first or only result rel */
 564                 estate->es_result_relation_info = resultRelInfos;
 565         }
 566         else
 567         {
 568
 569                 /*
 570                  * if no result relation, then set state appropriately
 571                  */
 572                 estate->es_result_relations = NULL;
 573                 estate->es_num_result_relations = 0;
 574                 estate->es_result_relation_info = NULL;
 575         }
 576
 577         /*
 578          * Have to lock relations selected for update
 579          */
 580         estate->es_rowMark = NIL;
 581         if (parseTree->rowMarks != NIL)
 582         {
 583                 List       *l;
 584
 585                 foreach(l, parseTree->rowMarks)
 586                 {
 587                         Index           rti = lfirsti(l);
 588                         Oid                     relid = getrelid(rti, rangeTable);
 589                         Relation        relation;
 590                         execRowMark *erm;
 591
 592                         relation = heap_open(relid, RowShareLock);
 593                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 594                         erm->relation = relation;
 595                         erm->rti = rti;
 596                         sprintf(erm->resname, "ctid%u", rti);
 597                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 598                 }
 599         }
 600
 601         /*
 602          * initialize the executor "tuple" table.
 603          */
 604         {
 605                 int                     nSlots = ExecCountSlotsNode(plan);
 606
 607                 estate->es_tupleTable = ExecCreateTupleTable(nSlots + 10); /* why add ten? - jolly */
 608         }
 609
 610         /* mark EvalPlanQual not active */
 611         estate->es_origPlan = plan;
 612         estate->es_evalPlanQual = NULL;
 613         estate->es_evTuple = NULL;
 614         estate->es_evTupleNull = NULL;
 615         estate->es_useEvalPlan = false;
 616
 617         /*
 618          * initialize the private state information for all the nodes in the
 619          * query tree.  This opens files, allocates storage and leaves us
 620          * ready to start processing tuples.
 621          */
 622         ExecInitNode(plan, estate, NULL);
 623
 624         /*
 625          * Get the tuple descriptor describing the type of tuples to return.
 626          * (this is especially important if we are creating a relation with
 627          * "retrieve into")
 628          */
 629         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 630
 631         /*
 632          * Initialize the junk filter if needed. SELECT and INSERT queries
 633          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 634          * DELETE always need one, since there's always a junk 'ctid'
 635          * attribute present --- no need to look first.
 636          */
 637         {
 638                 bool            junk_filter_needed = false;
 639                 List       *tlist;
 640
 641                 switch (operation)
 642                 {
 643                         case CMD_SELECT:
 644                         case CMD_INSERT:
 645                                 foreach(tlist, plan->targetlist)
 646                                 {
 647                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 648
 649                                         if (tle->resdom->resjunk)
 650                                         {
 651                                                 junk_filter_needed = true;
 652                                                 break;
 653                                         }
 654                                 }
 655                                 break;
 656                         case CMD_UPDATE:
 657                         case CMD_DELETE:
 658                                 junk_filter_needed = true;
 659                                 break;
 660                         default:
 661                                 break;
 662                 }
 663
 664                 if (junk_filter_needed)
 665                 {
 666
 667                         /*
 668                          * If there are multiple result relations, each one needs its
 669                          * own junk filter.  Note this is only possible for
 670                          * UPDATE/DELETE, so we can't be fooled by some needing a
 671                          * filter and some not.
 672                          */
 673                         if (parseTree->resultRelations != NIL)
 674                         {
 675                                 List       *subplans;
 676                                 ResultRelInfo *resultRelInfo;
 677
 678                                 /* Top plan had better be an Append here. */
 679                                 Assert(IsA(plan, Append));
 680                                 Assert(((Append *) plan)->isTarget);
 681                                 subplans = ((Append *) plan)->appendplans;
 682                                 Assert(length(subplans) == estate->es_num_result_relations);
 683                                 resultRelInfo = estate->es_result_relations;
 684                                 while (subplans != NIL)
 685                                 {
 686                                         Plan       *subplan = (Plan *) lfirst(subplans);
 687                                         JunkFilter *j;
 688
 689                                         j = ExecInitJunkFilter(subplan->targetlist,
 690                                                                                    ExecGetTupType(subplan));
 691                                         resultRelInfo->ri_junkFilter = j;
 692                                         resultRelInfo++;
 693                                         subplans = lnext(subplans);
 694                                 }
 695
 696                                 /*
 697                                  * Set active junkfilter too; at this point ExecInitAppend
 698                                  * has already selected an active result relation...
 699                                  */
 700                                 estate->es_junkFilter =
 701                                         estate->es_result_relation_info->ri_junkFilter;
 702                         }
 703                         else
 704                         {
 705                                 /* Normal case with just one JunkFilter */
 706                                 JunkFilter *j = ExecInitJunkFilter(plan->targetlist,
 707                                                                                                    tupType);
 708
 709                                 estate->es_junkFilter = j;
 710                                 if (estate->es_result_relation_info)
 711                                         estate->es_result_relation_info->ri_junkFilter = j;
 712
 713                                 /* For SELECT, want to return the cleaned tuple type */
 714                                 if (operation == CMD_SELECT)
 715                                         tupType = j->jf_cleanTupType;
 716                         }
 717                 }
 718                 else
 719                         estate->es_junkFilter = NULL;
 720         }
 721
 722         /*
 723          * initialize the "into" relation
 724          */
 725         intoRelationDesc = (Relation) NULL;
 726
 727         if (operation == CMD_SELECT)
 728         {
 729                 char       *intoName;
 730                 Oid                     intoRelationId;
 731                 TupleDesc       tupdesc;
 732
 733                 if (!parseTree->isPortal)
 734                 {
 735
 736                         /*
 737                          * a select into table
 738                          */
 739                         if (parseTree->into != NULL)
 740                         {
 741
 742                                 /*
 743                                  * create the "into" relation
 744                                  */
 745                                 intoName = parseTree->into;
 746
 747                                 /*
 748                                  * have to copy tupType to get rid of constraints
 749                                  */
 750                                 tupdesc = CreateTupleDescCopy(tupType);
 751
 752                                 intoRelationId =
 753                                         heap_create_with_catalog(intoName,
 754                                                                                          tupdesc,
 755                                                                                          RELKIND_RELATION,
 756                                                                                          parseTree->isTemp,
 757                                                                                          allowSystemTableMods);
 758
 759                                 FreeTupleDesc(tupdesc);
 760
 761                                 /*
 762                                  * Advance command counter so that the newly-created
 763                                  * relation's catalog tuples will be visible to heap_open.
 764                                  */
 765                                 CommandCounterIncrement();
 766
 767                                 /*
 768                                  * If necessary, create a TOAST table for the into
 769                                  * relation. Note that AlterTableCreateToastTable ends
 770                                  * with CommandCounterIncrement(), so that the TOAST table
 771                                  * will be visible for insertion.
 772                                  */
 773                                 AlterTableCreateToastTable(intoName, true);
 774
 775                                 intoRelationDesc = heap_open(intoRelationId,
 776                                                                                          AccessExclusiveLock);
 777                         }
 778                 }
 779         }
 780
 781         estate->es_into_relation_descriptor = intoRelationDesc;
 782
 783         return tupType;
 784 }
 785
 786 /*
 787  * Initialize ResultRelInfo data for one result relation
 788  */
 789 static void
 790 initResultRelInfo(ResultRelInfo *resultRelInfo,
 791                                   Index resultRelationIndex,
 792                                   List *rangeTable,
 793                                   CmdType operation)
 794 {
 795         Oid                     resultRelationOid;
 796         Relation        resultRelationDesc;
 797
 798         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 799         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 800
 801         switch (resultRelationDesc->rd_rel->relkind)
 802         {
 803                 case RELKIND_SEQUENCE:
 804                         elog(ERROR, "You can't change sequence relation %s",
 805                                  RelationGetRelationName(resultRelationDesc));
 806                         break;
 807                 case RELKIND_TOASTVALUE:
 808                         elog(ERROR, "You can't change toast relation %s",
 809                                  RelationGetRelationName(resultRelationDesc));
 810                         break;
 811                 case RELKIND_VIEW:
 812                         elog(ERROR, "You can't change view relation %s",
 813                                  RelationGetRelationName(resultRelationDesc));
 814                         break;
 815         }
 816
 817         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 818         resultRelInfo->type = T_ResultRelInfo;
 819         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 820         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 821         resultRelInfo->ri_NumIndices = 0;
 822         resultRelInfo->ri_IndexRelationDescs = NULL;
 823         resultRelInfo->ri_IndexRelationInfo = NULL;
 824         resultRelInfo->ri_ConstraintExprs = NULL;
 825         resultRelInfo->ri_junkFilter = NULL;
 826
 827         /*
 828          * If there are indices on the result relation, open them and save
 829          * descriptors in the result relation info, so that we can add new
 830          * index entries for the tuples we add/update.  We need not do this
 831          * for a DELETE, however, since deletion doesn't affect indexes.
 832          */
 833         if (resultRelationDesc->rd_rel->relhasindex &&
 834                 operation != CMD_DELETE)
 835                 ExecOpenIndices(resultRelInfo);
 836 }
 837
 838 /* ----------------------------------------------------------------
 839  *              EndPlan
 840  *
 841  *              Cleans up the query plan -- closes files and free up storages
 842  * ----------------------------------------------------------------
 843  */
 844 static void
 845 EndPlan(Plan *plan, EState *estate)
 846 {
 847         ResultRelInfo *resultRelInfo;
 848         int                     i;
 849         List       *l;
 850
 851         /*
 852          * shut down any PlanQual processing we were doing
 853          */
 854         if (estate->es_evalPlanQual != NULL)
 855                 EndEvalPlanQual(estate);
 856
 857         /*
 858          * shut down the node-type-specific query processing
 859          */
 860         ExecEndNode(plan, plan);
 861
 862         /*
 863          * destroy the executor "tuple" table.
 864          */
 865         ExecDropTupleTable(estate->es_tupleTable, true);
 866         estate->es_tupleTable = NULL;
 867
 868         /*
 869          * close the result relation(s) if any, but hold locks until xact
 870          * commit.      Also clean up junkfilters if present.
 871          */
 872         resultRelInfo = estate->es_result_relations;
 873         for (i = estate->es_num_result_relations; i > 0; i--)
 874         {
 875                 /* Close indices and then the relation itself */
 876                 ExecCloseIndices(resultRelInfo);
 877                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 878                 /* Delete the junkfilter if any */
 879                 if (resultRelInfo->ri_junkFilter != NULL)
 880                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 881                 resultRelInfo++;
 882         }
 883
 884         /*
 885          * close the "into" relation if necessary, again keeping lock
 886          */
 887         if (estate->es_into_relation_descriptor != NULL)
 888                 heap_close(estate->es_into_relation_descriptor, NoLock);
 889
 890         /*
 891          * There might be a junkfilter without a result relation.
 892          */
 893         if (estate->es_num_result_relations == 0 &&
 894                 estate->es_junkFilter != NULL)
 895         {
 896                 ExecFreeJunkFilter(estate->es_junkFilter);
 897                 estate->es_junkFilter = NULL;
 898         }
 899
 900         /*
 901          * close any relations selected FOR UPDATE, again keeping locks
 902          */
 903         foreach(l, estate->es_rowMark)
 904         {
 905                 execRowMark *erm = lfirst(l);
 906
 907                 heap_close(erm->relation, NoLock);
 908         }
 909 }
 910
 911 /* ----------------------------------------------------------------
 912  *              ExecutePlan
 913  *
 914  *              processes the query plan to retrieve 'numberTuples' tuples in the
 915  *              direction specified.
 916  *              Retrieves all tuples if tupleCount is 0
 917  *
 918  *              result is either a slot containing the last tuple in the case
 919  *              of a RETRIEVE or NULL otherwise.
 920  *
 921  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 922  * user can see it
 923  * ----------------------------------------------------------------
 924  */
 925 static TupleTableSlot *
 926 ExecutePlan(EState *estate,
 927                         Plan *plan,
 928                         CmdType operation,
 929                         long numberTuples,
 930                         ScanDirection direction,
 931                         DestReceiver *destfunc)
 932 {
 933         JunkFilter *junkfilter;
 934         TupleTableSlot *slot;
 935         ItemPointer tupleid = NULL;
 936         ItemPointerData tuple_ctid;
 937         long            current_tuple_count;
 938         TupleTableSlot *result;
 939
 940         /*
 941          * initialize local variables
 942          */
 943         slot = NULL;
 944         current_tuple_count = 0;
 945         result = NULL;
 946
 947         /*
 948          * Set the direction.
 949          */
 950         estate->es_direction = direction;
 951
 952         /*
 953          * Loop until we've processed the proper number of tuples from the
 954          * plan.
 955          */
 956
 957         for (;;)
 958         {
 959                 /* Reset the per-output-tuple exprcontext */
 960                 ResetPerTupleExprContext(estate);
 961
 962                 /*
 963                  * Execute the plan and obtain a tuple
 964                  */
 965                 /* at the top level, the parent of a plan (2nd arg) is itself */
 966 lnext:  ;
 967                 if (estate->es_useEvalPlan)
 968                 {
 969                         slot = EvalPlanQualNext(estate);
 970                         if (TupIsNull(slot))
 971                                 slot = ExecProcNode(plan, plan);
 972                 }
 973                 else
 974                         slot = ExecProcNode(plan, plan);
 975
 976                 /*
 977                  * if the tuple is null, then we assume there is nothing more to
 978                  * process so we just return null...
 979                  */
 980                 if (TupIsNull(slot))
 981                 {
 982                         result = NULL;
 983                         break;
 984                 }
 985
 986                 /*
 987                  * if we have a junk filter, then project a new tuple with the
 988                  * junk removed.
 989                  *
 990                  * Store this new "clean" tuple in the place of the original tuple.
 991                  *
 992                  * Also, extract all the junk information we need.
 993                  */
 994                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 995                 {
 996                         Datum           datum;
 997                         HeapTuple       newTuple;
 998                         bool            isNull;
 999
1000                         /*
1001                          * extract the 'ctid' junk attribute.
1002                          */
1003                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1004                         {
1005                                 if (!ExecGetJunkAttribute(junkfilter,
1006                                                                                   slot,
1007                                                                                   "ctid",
1008                                                                                   &datum,
1009                                                                                   &isNull))
1010                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1011
1012                                 /* shouldn't ever get a null result... */
1013                                 if (isNull)
1014                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1015
1016                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1017                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1018                                                                                  * ctid!! */
1019                                 tupleid = &tuple_ctid;
1020                         }
1021                         else if (estate->es_rowMark != NIL)
1022                         {
1023                                 List       *l;
1024
1025                 lmark:  ;
1026                                 foreach(l, estate->es_rowMark)
1027                                 {
1028                                         execRowMark *erm = lfirst(l);
1029                                         Buffer          buffer;
1030                                         HeapTupleData tuple;
1031                                         TupleTableSlot *newSlot;
1032                                         int                     test;
1033
1034                                         if (!ExecGetJunkAttribute(junkfilter,
1035                                                                                           slot,
1036                                                                                           erm->resname,
1037                                                                                           &datum,
1038                                                                                           &isNull))
1039                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1040                                                          erm->resname);
1041
1042                                         /* shouldn't ever get a null result... */
1043                                         if (isNull)
1044                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1045                                                          erm->resname);
1046
1047                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1048                                         test = heap_mark4update(erm->relation, &tuple, &buffer);
1049                                         ReleaseBuffer(buffer);
1050                                         switch (test)
1051                                         {
1052                                                 case HeapTupleSelfUpdated:
1053                                                 case HeapTupleMayBeUpdated:
1054                                                         break;
1055
1056                                                 case HeapTupleUpdated:
1057                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1058                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1059                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1060                                                                   (ItemPointer) DatumGetPointer(datum))))
1061                                                         {
1062                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1063                                                                 if (!(TupIsNull(newSlot)))
1064                                                                 {
1065                                                                         slot = newSlot;
1066                                                                         estate->es_useEvalPlan = true;
1067                                                                         goto lmark;
1068                                                                 }
1069                                                         }
1070
1071                                                         /*
1072                                                          * if tuple was deleted or PlanQual failed for
1073                                                          * updated tuple - we must not return this
1074                                                          * tuple!
1075                                                          */
1076                                                         goto lnext;
1077
1078                                                 default:
1079                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1080                                                         return (NULL);
1081                                         }
1082                                 }
1083                         }
1084
1085                         /*
1086                          * Finally create a new "clean" tuple with all junk attributes
1087                          * removed
1088                          */
1089                         newTuple = ExecRemoveJunk(junkfilter, slot);
1090
1091                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1092                                                                   slot, /* destination slot */
1093                                                                   InvalidBuffer,                /* this tuple has no
1094                                                                                                                  * buffer */
1095                                                                   true);                /* tuple should be pfreed */
1096                 }                                               /* if (junkfilter... */
1097
1098                 /*
1099                  * now that we have a tuple, do the appropriate thing with it..
1100                  * either return it to the user, add it to a relation someplace,
1101                  * delete it from a relation, or modify some of its attributes.
1102                  */
1103
1104                 switch (operation)
1105                 {
1106                         case CMD_SELECT:
1107                                 ExecRetrieve(slot,              /* slot containing tuple */
1108                                                          destfunc,      /* destination's tuple-receiver
1109                                                                                  * obj */
1110                                                          estate);       /* */
1111                                 result = slot;
1112                                 break;
1113
1114                         case CMD_INSERT:
1115                                 ExecAppend(slot, tupleid, estate);
1116                                 result = NULL;
1117                                 break;
1118
1119                         case CMD_DELETE:
1120                                 ExecDelete(slot, tupleid, estate);
1121                                 result = NULL;
1122                                 break;
1123
1124                         case CMD_UPDATE:
1125                                 ExecReplace(slot, tupleid, estate);
1126                                 result = NULL;
1127                                 break;
1128
1129                         default:
1130                                 elog(DEBUG, "ExecutePlan: unknown operation in queryDesc");
1131                                 result = NULL;
1132                                 break;
1133                 }
1134
1135                 /*
1136                  * check our tuple count.. if we've processed the proper number
1137                  * then quit, else loop again and process more tuples..
1138                  */
1139                 current_tuple_count++;
1140                 if (numberTuples == current_tuple_count)
1141                         break;
1142         }
1143
1144         /*
1145          * here, result is either a slot containing a tuple in the case of a
1146          * RETRIEVE or NULL otherwise.
1147          */
1148         return result;
1149 }
1150
1151 /* ----------------------------------------------------------------
1152  *              ExecRetrieve
1153  *
1154  *              RETRIEVEs are easy.. we just pass the tuple to the appropriate
1155  *              print function.  The only complexity is when we do a
1156  *              "retrieve into", in which case we insert the tuple into
1157  *              the appropriate relation (note: this is a newly created relation
1158  *              so we don't need to worry about indices or locks.)
1159  * ----------------------------------------------------------------
1160  */
1161 static void
1162 ExecRetrieve(TupleTableSlot *slot,
1163                          DestReceiver *destfunc,
1164                          EState *estate)
1165 {
1166         HeapTuple       tuple;
1167         TupleDesc       attrtype;
1168
1169         /*
1170          * get the heap tuple out of the tuple table slot
1171          */
1172         tuple = slot->val;
1173         attrtype = slot->ttc_tupleDescriptor;
1174
1175         /*
1176          * insert the tuple into the "into relation"
1177          */
1178         if (estate->es_into_relation_descriptor != NULL)
1179         {
1180                 heap_insert(estate->es_into_relation_descriptor, tuple);
1181                 IncrAppended();
1182         }
1183
1184         /*
1185          * send the tuple to the front end (or the screen)
1186          */
1187         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1188         IncrRetrieved();
1189         (estate->es_processed)++;
1190 }
1191
1192 /* ----------------------------------------------------------------
1193  *              ExecAppend
1194  *
1195  *              APPENDs are trickier.. we have to insert the tuple into
1196  *              the base relation and insert appropriate tuples into the
1197  *              index relations.
1198  * ----------------------------------------------------------------
1199  */
1200
1201 static void
1202 ExecAppend(TupleTableSlot *slot,
1203                    ItemPointer tupleid,
1204                    EState *estate)
1205 {
1206         HeapTuple       tuple;
1207         ResultRelInfo *resultRelInfo;
1208         Relation        resultRelationDesc;
1209         int                     numIndices;
1210         Oid                     newId;
1211
1212         /*
1213          * get the heap tuple out of the tuple table slot
1214          */
1215         tuple = slot->val;
1216
1217         /*
1218          * get information on the (current) result relation
1219          */
1220         resultRelInfo = estate->es_result_relation_info;
1221         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1222
1223         /* BEFORE ROW INSERT Triggers */
1224         if (resultRelationDesc->trigdesc &&
1225         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1226         {
1227                 HeapTuple       newtuple;
1228
1229                 newtuple = ExecBRInsertTriggers(estate, resultRelationDesc, tuple);
1230
1231                 if (newtuple == NULL)   /* "do nothing" */
1232                         return;
1233
1234                 if (newtuple != tuple)  /* modified by Trigger(s) */
1235                 {
1236
1237                         /*
1238                          * Insert modified tuple into tuple table slot, replacing the
1239                          * original.  We assume that it was allocated in per-tuple
1240                          * memory context, and therefore will go away by itself. The
1241                          * tuple table slot should not try to clear it.
1242                          */
1243                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1244                         tuple = newtuple;
1245                 }
1246         }
1247
1248         /*
1249          * Check the constraints of the tuple
1250          */
1251         if (resultRelationDesc->rd_att->constr)
1252                 ExecConstraints("ExecAppend", resultRelInfo, slot, estate);
1253
1254         /*
1255          * insert the tuple
1256          */
1257         newId = heap_insert(resultRelationDesc, tuple);
1258
1259         IncrAppended();
1260         (estate->es_processed)++;
1261         estate->es_lastoid = newId;
1262
1263         /*
1264          * process indices
1265          *
1266          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1267          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1268          * field.
1269          */
1270         numIndices = resultRelInfo->ri_NumIndices;
1271         if (numIndices > 0)
1272                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1273
1274         /* AFTER ROW INSERT Triggers */
1275         if (resultRelationDesc->trigdesc)
1276                 ExecARInsertTriggers(estate, resultRelationDesc, tuple);
1277 }
1278
1279 /* ----------------------------------------------------------------
1280  *              ExecDelete
1281  *
1282  *              DELETE is like append, we delete the tuple and its
1283  *              index tuples.
1284  * ----------------------------------------------------------------
1285  */
1286 static void
1287 ExecDelete(TupleTableSlot *slot,
1288                    ItemPointer tupleid,
1289                    EState *estate)
1290 {
1291         ResultRelInfo *resultRelInfo;
1292         Relation        resultRelationDesc;
1293         ItemPointerData ctid;
1294         int                     result;
1295
1296         /*
1297          * get information on the (current) result relation
1298          */
1299         resultRelInfo = estate->es_result_relation_info;
1300         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1301
1302         /* BEFORE ROW DELETE Triggers */
1303         if (resultRelationDesc->trigdesc &&
1304         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1305         {
1306                 bool            dodelete;
1307
1308                 dodelete = ExecBRDeleteTriggers(estate, tupleid);
1309
1310                 if (!dodelete)                  /* "do nothing" */
1311                         return;
1312         }
1313
1314         /*
1315          * delete the tuple
1316          */
1317 ldelete:;
1318         result = heap_delete(resultRelationDesc, tupleid, &ctid);
1319         switch (result)
1320         {
1321                 case HeapTupleSelfUpdated:
1322                         return;
1323
1324                 case HeapTupleMayBeUpdated:
1325                         break;
1326
1327                 case HeapTupleUpdated:
1328                         if (XactIsoLevel == XACT_SERIALIZABLE)
1329                                 elog(ERROR, "Can't serialize access due to concurrent update");
1330                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1331                         {
1332                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1333                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1334
1335                                 if (!TupIsNull(epqslot))
1336                                 {
1337                                         *tupleid = ctid;
1338                                         goto ldelete;
1339                                 }
1340                         }
1341                         /* tuple already deleted; nothing to do */
1342                         return;
1343
1344                 default:
1345                         elog(ERROR, "Unknown status %u from heap_delete", result);
1346                         return;
1347         }
1348
1349         IncrDeleted();
1350         (estate->es_processed)++;
1351
1352         /*
1353          * Note: Normally one would think that we have to delete index tuples
1354          * associated with the heap tuple now..
1355          *
1356          * ... but in POSTGRES, we have no need to do this because the vacuum
1357          * daemon automatically opens an index scan and deletes index tuples
1358          * when it finds deleted heap tuples. -cim 9/27/89
1359          */
1360
1361         /* AFTER ROW DELETE Triggers */
1362         if (resultRelationDesc->trigdesc)
1363                 ExecARDeleteTriggers(estate, tupleid);
1364 }
1365
1366 /* ----------------------------------------------------------------
1367  *              ExecReplace
1368  *
1369  *              note: we can't run replace queries with transactions
1370  *              off because replaces are actually appends and our
1371  *              scan will mistakenly loop forever, replacing the tuple
1372  *              it just appended..      This should be fixed but until it
1373  *              is, we don't want to get stuck in an infinite loop
1374  *              which corrupts your database..
1375  * ----------------------------------------------------------------
1376  */
1377 static void
1378 ExecReplace(TupleTableSlot *slot,
1379                         ItemPointer tupleid,
1380                         EState *estate)
1381 {
1382         HeapTuple       tuple;
1383         ResultRelInfo *resultRelInfo;
1384         Relation        resultRelationDesc;
1385         ItemPointerData ctid;
1386         int                     result;
1387         int                     numIndices;
1388
1389         /*
1390          * abort the operation if not running transactions
1391          */
1392         if (IsBootstrapProcessingMode())
1393         {
1394                 elog(NOTICE, "ExecReplace: replace can't run without transactions");
1395                 return;
1396         }
1397
1398         /*
1399          * get the heap tuple out of the tuple table slot
1400          */
1401         tuple = slot->val;
1402
1403         /*
1404          * get information on the (current) result relation
1405          */
1406         resultRelInfo = estate->es_result_relation_info;
1407         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1408
1409         /* BEFORE ROW UPDATE Triggers */
1410         if (resultRelationDesc->trigdesc &&
1411         resultRelationDesc->trigdesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1412         {
1413                 HeapTuple       newtuple;
1414
1415                 newtuple = ExecBRUpdateTriggers(estate, tupleid, tuple);
1416
1417                 if (newtuple == NULL)   /* "do nothing" */
1418                         return;
1419
1420                 if (newtuple != tuple)  /* modified by Trigger(s) */
1421                 {
1422
1423                         /*
1424                          * Insert modified tuple into tuple table slot, replacing the
1425                          * original.  We assume that it was allocated in per-tuple
1426                          * memory context, and therefore will go away by itself. The
1427                          * tuple table slot should not try to clear it.
1428                          */
1429                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1430                         tuple = newtuple;
1431                 }
1432         }
1433
1434         /*
1435          * Check the constraints of the tuple
1436          *
1437          * If we generate a new candidate tuple after EvalPlanQual testing,
1438          * we must loop back here and recheck constraints.  (We don't need to
1439          * redo triggers, however.  If there are any BEFORE triggers then
1440          * trigger.c will have done mark4update to lock the correct tuple,
1441          * so there's no need to do them again.)
1442          */
1443 lreplace:;
1444         if (resultRelationDesc->rd_att->constr)
1445                 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1446
1447         /*
1448          * replace the heap tuple
1449          */
1450         result = heap_update(resultRelationDesc, tupleid, tuple, &ctid);
1451         switch (result)
1452         {
1453                 case HeapTupleSelfUpdated:
1454                         return;
1455
1456                 case HeapTupleMayBeUpdated:
1457                         break;
1458
1459                 case HeapTupleUpdated:
1460                         if (XactIsoLevel == XACT_SERIALIZABLE)
1461                                 elog(ERROR, "Can't serialize access due to concurrent update");
1462                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1463                         {
1464                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1465                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1466
1467                                 if (!TupIsNull(epqslot))
1468                                 {
1469                                         *tupleid = ctid;
1470                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1471                                         slot = ExecStoreTuple(tuple, slot, InvalidBuffer, true);
1472                                         goto lreplace;
1473                                 }
1474                         }
1475                         /* tuple already deleted; nothing to do */
1476                         return;
1477
1478                 default:
1479                         elog(ERROR, "Unknown status %u from heap_update", result);
1480                         return;
1481         }
1482
1483         IncrReplaced();
1484         (estate->es_processed)++;
1485
1486         /*
1487          * Note: instead of having to update the old index tuples associated
1488          * with the heap tuple, all we do is form and insert new index tuples.
1489          * This is because replaces are actually deletes and inserts and index
1490          * tuple deletion is done automagically by the vacuum daemon. All we
1491          * do is insert new index tuples.  -cim 9/27/89
1492          */
1493
1494         /*
1495          * process indices
1496          *
1497          * heap_update updates a tuple in the base relation by invalidating it
1498          * and then appending a new tuple to the relation.      As a side effect,
1499          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1500          * field.  So we now insert index tuples using the new tupleid stored
1501          * there.
1502          */
1503
1504         numIndices = resultRelInfo->ri_NumIndices;
1505         if (numIndices > 0)
1506                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, true);
1507
1508         /* AFTER ROW UPDATE Triggers */
1509         if (resultRelationDesc->trigdesc)
1510                 ExecARUpdateTriggers(estate, tupleid, tuple);
1511 }
1512
1513 static char *
1514 ExecRelCheck(ResultRelInfo *resultRelInfo,
1515                          TupleTableSlot *slot, EState *estate)
1516 {
1517         Relation        rel = resultRelInfo->ri_RelationDesc;
1518         int                     ncheck = rel->rd_att->constr->num_check;
1519         ConstrCheck *check = rel->rd_att->constr->check;
1520         ExprContext *econtext;
1521         MemoryContext oldContext;
1522         List       *qual;
1523         int                     i;
1524
1525         /*
1526          * If first time through for this result relation, build expression
1527          * nodetrees for rel's constraint expressions.  Keep them in the
1528          * per-query memory context so they'll survive throughout the query.
1529          */
1530         if (resultRelInfo->ri_ConstraintExprs == NULL)
1531         {
1532                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1533                 resultRelInfo->ri_ConstraintExprs =
1534                         (List **) palloc(ncheck * sizeof(List *));
1535                 for (i = 0; i < ncheck; i++)
1536                 {
1537                         qual = (List *) stringToNode(check[i].ccbin);
1538                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1539                 }
1540                 MemoryContextSwitchTo(oldContext);
1541         }
1542
1543         /*
1544          * We will use the EState's per-tuple context for evaluating
1545          * constraint expressions (creating it if it's not already there).
1546          */
1547         econtext = GetPerTupleExprContext(estate);
1548
1549         /* Arrange for econtext's scan tuple to be the tuple under test */
1550         econtext->ecxt_scantuple = slot;
1551
1552         /* And evaluate the constraints */
1553         for (i = 0; i < ncheck; i++)
1554         {
1555                 qual = resultRelInfo->ri_ConstraintExprs[i];
1556
1557                 /*
1558                  * NOTE: SQL92 specifies that a NULL result from a constraint
1559                  * expression is not to be treated as a failure.  Therefore, tell
1560                  * ExecQual to return TRUE for NULL.
1561                  */
1562                 if (!ExecQual(qual, econtext, true))
1563                         return check[i].ccname;
1564         }
1565
1566         /* NULL result means no error */
1567         return (char *) NULL;
1568 }
1569
1570 void
1571 ExecConstraints(char *caller, ResultRelInfo *resultRelInfo,
1572                                 TupleTableSlot *slot, EState *estate)
1573 {
1574         Relation        rel = resultRelInfo->ri_RelationDesc;
1575         HeapTuple       tuple = slot->val;
1576         TupleConstr *constr = rel->rd_att->constr;
1577
1578         Assert(constr);
1579
1580         if (constr->has_not_null)
1581         {
1582                 int                     natts = rel->rd_att->natts;
1583                 int                     attrChk;
1584
1585                 for (attrChk = 1; attrChk <= natts; attrChk++)
1586                 {
1587                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1588                                 heap_attisnull(tuple, attrChk))
1589                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1590                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1591                 }
1592         }
1593
1594         if (constr->num_check > 0)
1595         {
1596                 char       *failed;
1597
1598                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1599                         elog(ERROR, "%s: rejected due to CHECK constraint %s",
1600                                  caller, failed);
1601         }
1602 }
1603
1604 /*
1605  * Check a modified tuple to see if we want to process its updated version
1606  * under READ COMMITTED rules.
1607  *
1608  * See backend/executor/README for some info about how this works.
1609  */
1610 TupleTableSlot *
1611 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1612 {
1613         evalPlanQual *epq;
1614         EState     *epqstate;
1615         Relation        relation;
1616         HeapTupleData tuple;
1617         HeapTuple       copyTuple = NULL;
1618         int                     rtsize;
1619         bool            endNode;
1620
1621         Assert(rti != 0);
1622
1623         /*
1624          * find relation containing target tuple
1625          */
1626         if (estate->es_result_relation_info != NULL &&
1627                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1628         {
1629                 relation = estate->es_result_relation_info->ri_RelationDesc;
1630         }
1631         else
1632         {
1633                 List       *l;
1634
1635                 relation = NULL;
1636                 foreach(l, estate->es_rowMark)
1637                 {
1638                         if (((execRowMark *) lfirst(l))->rti == rti)
1639                         {
1640                                 relation = ((execRowMark *) lfirst(l))->relation;
1641                                 break;
1642                         }
1643                 }
1644                 if (relation == NULL)
1645                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1646         }
1647
1648         /*
1649          * fetch tid tuple
1650          *
1651          * Loop here to deal with updated or busy tuples
1652          */
1653         tuple.t_self = *tid;
1654         for (;;)
1655         {
1656                 Buffer          buffer;
1657
1658                 heap_fetch(relation, SnapshotDirty, &tuple, &buffer);
1659                 if (tuple.t_data != NULL)
1660                 {
1661                         TransactionId xwait = SnapshotDirty->xmax;
1662
1663                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1664                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1665
1666                         /*
1667                          * If tuple is being updated by other transaction then we have
1668                          * to wait for its commit/abort.
1669                          */
1670                         if (TransactionIdIsValid(xwait))
1671                         {
1672                                 ReleaseBuffer(buffer);
1673                                 XactLockTableWait(xwait);
1674                                 continue;
1675                         }
1676
1677                         /*
1678                          * We got tuple - now copy it for use by recheck query.
1679                          */
1680                         copyTuple = heap_copytuple(&tuple);
1681                         ReleaseBuffer(buffer);
1682                         break;
1683                 }
1684
1685                 /*
1686                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1687                  * Note that it's possible to get invalid SnapshotDirty->tid if
1688                  * tuple updated by this transaction. Have we to check this ?
1689                  */
1690                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1691                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1692                 {
1693                         /* updated, so look at the updated copy */
1694                         tuple.t_self = SnapshotDirty->tid;
1695                         continue;
1696                 }
1697
1698                 /*
1699                  * Deleted or updated by this transaction; forget it.
1700                  */
1701                 return NULL;
1702         }
1703
1704         /*
1705          * For UPDATE/DELETE we have to return tid of actual row we're
1706          * executing PQ for.
1707          */
1708         *tid = tuple.t_self;
1709
1710         /*
1711          * Need to run a recheck subquery.  Find or create a PQ stack entry.
1712          */
1713         epq = (evalPlanQual *) estate->es_evalPlanQual;
1714         rtsize = length(estate->es_range_table);
1715         endNode = true;
1716
1717         if (epq != NULL && epq->rti == 0)
1718         {
1719                 /* Top PQ stack entry is idle, so re-use it */
1720                 Assert(!(estate->es_useEvalPlan) &&
1721                            epq->estate.es_evalPlanQual == NULL);
1722                 epq->rti = rti;
1723                 endNode = false;
1724         }
1725
1726         /*
1727          * If this is request for another RTE - Ra, - then we have to check
1728          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1729          * updated again and we have to re-start old execution for Ra and
1730          * forget all what we done after Ra was suspended. Cool? -:))
1731          */
1732         if (epq != NULL && epq->rti != rti &&
1733                 epq->estate.es_evTuple[rti - 1] != NULL)
1734         {
1735                 do
1736                 {
1737                         evalPlanQual *oldepq;
1738
1739                         /* pop previous PlanQual from the stack */
1740                         epqstate = &(epq->estate);
1741                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1742                         Assert(oldepq->rti != 0);
1743                         /* stop execution */
1744                         ExecEndNode(epq->plan, epq->plan);
1745                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1746                         epqstate->es_tupleTable = NULL;
1747                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1748                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1749                         /* push current PQ to freePQ stack */
1750                         oldepq->free = epq;
1751                         epq = oldepq;
1752                         estate->es_evalPlanQual = (Pointer) epq;
1753                 } while (epq->rti != rti);
1754         }
1755
1756         /*
1757          * If we are requested for another RTE then we have to suspend
1758          * execution of current PlanQual and start execution for new one.
1759          */
1760         if (epq == NULL || epq->rti != rti)
1761         {
1762                 /* try to reuse plan used previously */
1763                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1764
1765                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1766                 {
1767                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1768                         newepq->free = NULL;
1769                         /*
1770                          * Each stack level has its own copy of the plan tree.  This
1771                          * is wasteful, but necessary as long as plan nodes point to
1772                          * exec state nodes rather than vice versa.  Note that copyfuncs.c
1773                          * doesn't attempt to copy the exec state nodes, which is a good
1774                          * thing in this situation.
1775                          */
1776                         newepq->plan = copyObject(estate->es_origPlan);
1777                         /*
1778                          * Init stack level's EState.  We share top level's copy of
1779                          * es_result_relations array and other non-changing status.
1780                          * We need our own tupletable, es_param_exec_vals, and other
1781                          * changeable state.
1782                          */
1783                         epqstate = &(newepq->estate);
1784                         memcpy(epqstate, estate, sizeof(EState));
1785                         epqstate->es_direction = ForwardScanDirection;
1786                         if (estate->es_origPlan->nParamExec > 0)
1787                                 epqstate->es_param_exec_vals = (ParamExecData *)
1788                                         palloc(estate->es_origPlan->nParamExec *
1789                                                    sizeof(ParamExecData));
1790                         epqstate->es_tupleTable = NULL;
1791                         epqstate->es_per_tuple_exprcontext = NULL;
1792                         /*
1793                          * Each epqstate must have its own es_evTupleNull state,
1794                          * but all the stack entries share es_evTuple state.  This
1795                          * allows sub-rechecks to inherit the value being examined by
1796                          * an outer recheck.
1797                          */
1798                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1799                         if (epq == NULL)
1800                         {
1801                                 /* first PQ stack entry */
1802                                 epqstate->es_evTuple = (HeapTuple *)
1803                                         palloc(rtsize * sizeof(HeapTuple));
1804                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1805                         }
1806                         else
1807                         {
1808                                 /* later stack entries share the same storage */
1809                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1810                         }
1811                 }
1812                 else
1813                 {
1814                         /* recycle previously used EState */
1815                         epqstate = &(newepq->estate);
1816                 }
1817                 /* push current PQ to the stack */
1818                 epqstate->es_evalPlanQual = (Pointer) epq;
1819                 epq = newepq;
1820                 estate->es_evalPlanQual = (Pointer) epq;
1821                 epq->rti = rti;
1822                 endNode = false;
1823         }
1824
1825         Assert(epq->rti == rti);
1826         epqstate = &(epq->estate);
1827
1828         /*
1829          * Ok - we're requested for the same RTE.  Unfortunately we still
1830          * have to end and restart execution of the plan, because ExecReScan
1831          * wouldn't ensure that upper plan nodes would reset themselves.  We
1832          * could make that work if insertion of the target tuple were integrated
1833          * with the Param mechanism somehow, so that the upper plan nodes know
1834          * that their children's outputs have changed.
1835          */
1836         if (endNode)
1837         {
1838                 /* stop execution */
1839                 ExecEndNode(epq->plan, epq->plan);
1840                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1841                 epqstate->es_tupleTable = NULL;
1842         }
1843
1844         /*
1845          * free old RTE' tuple, if any, and store target tuple where relation's
1846          * scan node will see it
1847          */
1848         if (epqstate->es_evTuple[rti - 1] != NULL)
1849                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1850         epqstate->es_evTuple[rti - 1] = copyTuple;
1851
1852         /*
1853          * Initialize for new recheck query; be careful to copy down state
1854          * that might have changed in top EState.
1855          */
1856         epqstate->es_result_relation_info = estate->es_result_relation_info;
1857         epqstate->es_junkFilter = estate->es_junkFilter;
1858         if (estate->es_origPlan->nParamExec > 0)
1859                 memset(epqstate->es_param_exec_vals, 0,
1860                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1861         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1862         epqstate->es_useEvalPlan = false;
1863         Assert(epqstate->es_tupleTable == NULL);
1864         epqstate->es_tupleTable =
1865                 ExecCreateTupleTable(estate->es_tupleTable->size);
1866
1867         ExecInitNode(epq->plan, epqstate, NULL);
1868
1869         return EvalPlanQualNext(estate);
1870 }
1871
1872 static TupleTableSlot *
1873 EvalPlanQualNext(EState *estate)
1874 {
1875         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1876         EState     *epqstate = &(epq->estate);
1877         evalPlanQual *oldepq;
1878         TupleTableSlot *slot;
1879
1880         Assert(epq->rti != 0);
1881
1882 lpqnext:;
1883         slot = ExecProcNode(epq->plan, epq->plan);
1884
1885         /*
1886          * No more tuples for this PQ. Continue previous one.
1887          */
1888         if (TupIsNull(slot))
1889         {
1890                 /* stop execution */
1891                 ExecEndNode(epq->plan, epq->plan);
1892                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1893                 epqstate->es_tupleTable = NULL;
1894                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1895                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1896                 /* pop old PQ from the stack */
1897                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1898                 if (oldepq == (evalPlanQual *) NULL)
1899                 {
1900                         epq->rti = 0;           /* this is the first (oldest) */
1901                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1902                         return (NULL);          /* continue Query execution   */
1903                 }
1904                 Assert(oldepq->rti != 0);
1905                 /* push current PQ to freePQ stack */
1906                 oldepq->free = epq;
1907                 epq = oldepq;
1908                 epqstate = &(epq->estate);
1909                 estate->es_evalPlanQual = (Pointer) epq;
1910                 goto lpqnext;
1911         }
1912
1913         return (slot);
1914 }
1915
1916 static void
1917 EndEvalPlanQual(EState *estate)
1918 {
1919         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1920         EState     *epqstate = &(epq->estate);
1921         evalPlanQual *oldepq;
1922
1923         if (epq->rti == 0)                      /* plans already shutdowned */
1924         {
1925                 Assert(epq->estate.es_evalPlanQual == NULL);
1926                 return;
1927         }
1928
1929         for (;;)
1930         {
1931                 /* stop execution */
1932                 ExecEndNode(epq->plan, epq->plan);
1933                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1934                 epqstate->es_tupleTable = NULL;
1935                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1936                 {
1937                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1938                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1939                 }
1940                 /* pop old PQ from the stack */
1941                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1942                 if (oldepq == (evalPlanQual *) NULL)
1943                 {
1944                         epq->rti = 0;           /* this is the first (oldest) */
1945                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1946                         break;
1947                 }
1948                 Assert(oldepq->rti != 0);
1949                 /* push current PQ to freePQ stack */
1950                 oldepq->free = epq;
1951                 epq = oldepq;
1952                 epqstate = &(epq->estate);
1953                 estate->es_evalPlanQual = (Pointer) epq;
1954         }
1955 }