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

   1 /*-------------------------------------------------------------------------
   2  *
   3  * execMain.c
   4  *        top level executor interface routines
   5  *
   6  * INTERFACE ROUTINES
   7  *      ExecutorStart()
   8  *      ExecutorRun()
   9  *      ExecutorEnd()
  10  *
  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),
  12  *      ExecutorRun() and ExecutorEnd()
  13  *
  14  *      These three procedures are the external interfaces to the executor.
  15  *      In each case, the query descriptor and the execution state is required
  16  *      as arguments
  17  *
  18  *      ExecutorStart() must be called at the beginning of any execution of any
  19  *      query plan and ExecutorEnd() should always be called at the end of
  20  *      execution of a plan.
  21  *
  22  *      ExecutorRun accepts direction and count arguments that specify whether
  23  *      the plan is to be executed forwards, backwards, and for how many tuples.
  24  *
  25  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  26  * Portions Copyright (c) 1994, Regents of the University of California
  27  *
  28  *
  29  * IDENTIFICATION
  30  *        $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.189 2002/12/05 04:04:42 momjian Exp $
  31  *
  32  *-------------------------------------------------------------------------
  33  */
  34 #include "postgres.h"
  35
  36 #include "access/heapam.h"
  37 #include "catalog/heap.h"
  38 #include "catalog/namespace.h"
  39 #include "commands/tablecmds.h"
  40 #include "commands/trigger.h"
  41 #include "executor/execdebug.h"
  42 #include "executor/execdefs.h"
  43 #include "miscadmin.h"
  44 #include "optimizer/var.h"
  45 #include "parser/parsetree.h"
  46 #include "utils/acl.h"
  47 #include "utils/lsyscache.h"
  48
  49
  50 /* decls for local routines only used within this module */
  51 static TupleDesc InitPlan(CmdType operation,
  52                  Query *parseTree,
  53                  Plan *plan,
  54                  EState *estate);
  55 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  56                                   Index resultRelationIndex,
  57                                   List *rangeTable,
  58                                   CmdType operation);
  59 static void EndPlan(Plan *plan, EState *estate);
  60 static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan,
  61                         CmdType operation,
  62                         long numberTuples,
  63                         ScanDirection direction,
  64                         DestReceiver *destfunc);
  65 static void ExecSelect(TupleTableSlot *slot,
  66                    DestReceiver *destfunc,
  67                    EState *estate);
  68 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  69                    EState *estate);
  70 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  71                    EState *estate);
  72 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  73                    EState *estate);
  74 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  75 static void EndEvalPlanQual(EState *estate);
  76 static void ExecCheckQueryPerms(CmdType operation, Query *parseTree,
  77                                         Plan *plan);
  78 static void ExecCheckPlanPerms(Plan *plan, List *rangeTable,
  79                                    CmdType operation);
  80 static void ExecCheckRTPerms(List *rangeTable, CmdType operation);
  81 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  82
  83 /* end of local decls */
  84
  85
  86 /* ----------------------------------------------------------------
  87  *              ExecutorStart
  88  *
  89  *              This routine must be called at the beginning of any execution of any
  90  *              query plan
  91  *
  92  *              returns a TupleDesc which describes the attributes of the tuples to
  93  *              be returned by the query.  (Same value is saved in queryDesc)
  94  *
  95  * NB: the CurrentMemoryContext when this is called must be the context
  96  * to be used as the per-query context for the query plan.      ExecutorRun()
  97  * and ExecutorEnd() must be called in this same memory context.
  98  * ----------------------------------------------------------------
  99  */
 100 TupleDesc
 101 ExecutorStart(QueryDesc *queryDesc, EState *estate)
 102 {
 103         TupleDesc       result;
 104
 105         /* sanity checks */
 106         Assert(queryDesc != NULL);
 107
 108         if (queryDesc->plantree->nParamExec > 0)
 109                 estate->es_param_exec_vals = (ParamExecData *)
 110                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 111
 112         /*
 113          * Make our own private copy of the current query snapshot data.
 114          *
 115          * This "freezes" our idea of which tuples are good and which are not for
 116          * the life of this query, even if it outlives the current command and
 117          * current snapshot.
 118          */
 119         estate->es_snapshot = CopyQuerySnapshot();
 120
 121         /*
 122          * Initialize the plan
 123          */
 124         result = InitPlan(queryDesc->operation,
 125                                           queryDesc->parsetree,
 126                                           queryDesc->plantree,
 127                                           estate);
 128
 129         queryDesc->tupDesc = result;
 130
 131         return result;
 132 }
 133
 134 /* ----------------------------------------------------------------
 135  *              ExecutorRun
 136  *
 137  *              This is the main routine of the executor module. It accepts
 138  *              the query descriptor from the traffic cop and executes the
 139  *              query plan.
 140  *
 141  *              ExecutorStart must have been called already.
 142  *
 143  *              If direction is NoMovementScanDirection then nothing is done
 144  *              except to start up/shut down the destination.  Otherwise,
 145  *              we retrieve up to 'count' tuples in the specified direction.
 146  *
 147  *              Note: count = 0 is interpreted as no portal limit, e.g. run to
 148  *              completion.
 149  *
 150  * ----------------------------------------------------------------
 151  */
 152 TupleTableSlot *
 153 ExecutorRun(QueryDesc *queryDesc, EState *estate,
 154                         ScanDirection direction, long count)
 155 {
 156         CmdType         operation;
 157         Plan       *plan;
 158         CommandDest dest;
 159         DestReceiver *destfunc;
 160         TupleTableSlot *result;
 161
 162         /*
 163          * sanity checks
 164          */
 165         Assert(queryDesc != NULL);
 166
 167         /*
 168          * extract information from the query descriptor and the query
 169          * feature.
 170          */
 171         operation = queryDesc->operation;
 172         plan = queryDesc->plantree;
 173         dest = queryDesc->dest;
 174
 175         /*
 176          * startup tuple receiver
 177          */
 178         estate->es_processed = 0;
 179         estate->es_lastoid = InvalidOid;
 180
 181         destfunc = DestToFunction(dest);
 182         (*destfunc->setup) (destfunc, (int) operation,
 183                                                 queryDesc->portalName, queryDesc->tupDesc);
 184
 185         /*
 186          * run plan
 187          */
 188         if (direction == NoMovementScanDirection)
 189                 result = NULL;
 190         else
 191                 result = ExecutePlan(estate,
 192                                                          plan,
 193                                                          operation,
 194                                                          count,
 195                                                          direction,
 196                                                          destfunc);
 197
 198         /*
 199          * shutdown receiver
 200          */
 201         (*destfunc->cleanup) (destfunc);
 202
 203         return result;
 204 }
 205
 206 /* ----------------------------------------------------------------
 207  *              ExecutorEnd
 208  *
 209  *              This routine must be called at the end of execution of any
 210  *              query plan
 211  * ----------------------------------------------------------------
 212  */
 213 void
 214 ExecutorEnd(QueryDesc *queryDesc, EState *estate)
 215 {
 216         /* sanity checks */
 217         Assert(queryDesc != NULL);
 218
 219         EndPlan(queryDesc->plantree, estate);
 220
 221         if (estate->es_snapshot != NULL)
 222         {
 223                 if (estate->es_snapshot->xcnt > 0)
 224                         pfree(estate->es_snapshot->xip);
 225                 pfree(estate->es_snapshot);
 226                 estate->es_snapshot = NULL;
 227         }
 228
 229         if (estate->es_param_exec_vals != NULL)
 230         {
 231                 pfree(estate->es_param_exec_vals);
 232                 estate->es_param_exec_vals = NULL;
 233         }
 234 }
 235
 236
 237 /*
 238  * ExecCheckQueryPerms
 239  *              Check access permissions for all relations referenced in a query.
 240  */
 241 static void
 242 ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan)
 243 {
 244         /*
 245          * Check RTEs in the query's primary rangetable.
 246          */
 247         ExecCheckRTPerms(parseTree->rtable, operation);
 248
 249         /*
 250          * Search for subplans and APPEND nodes to check their rangetables.
 251          */
 252         ExecCheckPlanPerms(plan, parseTree->rtable, operation);
 253 }
 254
 255 /*
 256  * ExecCheckPlanPerms
 257  *              Recursively scan the plan tree to check access permissions in
 258  *              subplans.
 259  */
 260 static void
 261 ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation)
 262 {
 263         List       *subp;
 264
 265         if (plan == NULL)
 266                 return;
 267
 268         /* Check subplans, which we assume are plain SELECT queries */
 269
 270         foreach(subp, plan->initPlan)
 271         {
 272                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 273
 274                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 275                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 276         }
 277         foreach(subp, plan->subPlan)
 278         {
 279                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 280
 281                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 282                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 283         }
 284
 285         /* Check lower plan nodes */
 286
 287         ExecCheckPlanPerms(plan->lefttree, rangeTable, operation);
 288         ExecCheckPlanPerms(plan->righttree, rangeTable, operation);
 289
 290         /* Do node-type-specific checks */
 291
 292         switch (nodeTag(plan))
 293         {
 294                 case T_SubqueryScan:
 295                         {
 296                                 SubqueryScan *scan = (SubqueryScan *) plan;
 297                                 RangeTblEntry *rte;
 298
 299                                 /* Recursively check the subquery */
 300                                 rte = rt_fetch(scan->scan.scanrelid, rangeTable);
 301                                 Assert(rte->rtekind == RTE_SUBQUERY);
 302                                 ExecCheckQueryPerms(operation, rte->subquery, scan->subplan);
 303                                 break;
 304                         }
 305                 case T_Append:
 306                         {
 307                                 Append     *app = (Append *) plan;
 308                                 List       *appendplans;
 309
 310                                 foreach(appendplans, app->appendplans)
 311                                 {
 312                                         ExecCheckPlanPerms((Plan *) lfirst(appendplans),
 313                                                                            rangeTable,
 314                                                                            operation);
 315                                 }
 316                                 break;
 317                         }
 318
 319                 default:
 320                         break;
 321         }
 322 }
 323
 324 /*
 325  * ExecCheckRTPerms
 326  *              Check access permissions for all relations listed in a range table.
 327  */
 328 static void
 329 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 330 {
 331         List       *lp;
 332
 333         foreach(lp, rangeTable)
 334         {
 335                 RangeTblEntry *rte = lfirst(lp);
 336
 337                 ExecCheckRTEPerms(rte, operation);
 338         }
 339 }
 340
 341 /*
 342  * ExecCheckRTEPerms
 343  *              Check access permissions for a single RTE.
 344  */
 345 static void
 346 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 347 {
 348         Oid                     relOid;
 349         AclId           userid;
 350         AclResult       aclcheck_result;
 351
 352         /*
 353          * Only plain-relation RTEs need to be checked here.  Subquery RTEs
 354          * will be checked when ExecCheckPlanPerms finds the SubqueryScan
 355          * node, and function RTEs are checked by init_fcache when the
 356          * function is prepared for execution.  Join and special RTEs need no
 357          * checks.
 358          */
 359         if (rte->rtekind != RTE_RELATION)
 360                 return;
 361
 362         relOid = rte->relid;
 363
 364         /*
 365          * userid to check as: current user unless we have a setuid
 366          * indication.
 367          *
 368          * Note: GetUserId() is presently fast enough that there's no harm in
 369          * calling it separately for each RTE.  If that stops being true, we
 370          * could call it once in ExecCheckQueryPerms and pass the userid down
 371          * from there.  But for now, no need for the extra clutter.
 372          */
 373         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 374
 375 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 376
 377         if (rte->checkForRead)
 378         {
 379                 aclcheck_result = CHECK(ACL_SELECT);
 380                 if (aclcheck_result != ACLCHECK_OK)
 381                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 382         }
 383
 384         if (rte->checkForWrite)
 385         {
 386                 /*
 387                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 388                  * Right now we don't distinguish that from true update as far as
 389                  * permissions checks are concerned.
 390                  */
 391                 switch (operation)
 392                 {
 393                         case CMD_INSERT:
 394                                 aclcheck_result = CHECK(ACL_INSERT);
 395                                 break;
 396                         case CMD_SELECT:
 397                         case CMD_UPDATE:
 398                                 aclcheck_result = CHECK(ACL_UPDATE);
 399                                 break;
 400                         case CMD_DELETE:
 401                                 aclcheck_result = CHECK(ACL_DELETE);
 402                                 break;
 403                         default:
 404                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 405                                          operation);
 406                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 407                                 break;
 408                 }
 409                 if (aclcheck_result != ACLCHECK_OK)
 410                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 411         }
 412 }
 413
 414
 415 /* ===============================================================
 416  * ===============================================================
 417                                                  static routines follow
 418  * ===============================================================
 419  * ===============================================================
 420  */
 421
 422 typedef struct execRowMark
 423 {
 424         Relation        relation;
 425         Index           rti;
 426         char            resname[32];
 427 } execRowMark;
 428
 429 typedef struct evalPlanQual
 430 {
 431         Plan       *plan;
 432         Index           rti;
 433         EState          estate;
 434         struct evalPlanQual *free;
 435 } evalPlanQual;
 436
 437 /* ----------------------------------------------------------------
 438  *              InitPlan
 439  *
 440  *              Initializes the query plan: open files, allocate storage
 441  *              and start up the rule manager
 442  * ----------------------------------------------------------------
 443  */
 444 static TupleDesc
 445 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 446 {
 447         List       *rangeTable;
 448         Relation        intoRelationDesc;
 449         TupleDesc       tupType;
 450
 451         /*
 452          * Do permissions checks.
 453          */
 454         ExecCheckQueryPerms(operation, parseTree, plan);
 455
 456         /*
 457          * get information from query descriptor
 458          */
 459         rangeTable = parseTree->rtable;
 460
 461         /*
 462          * initialize the node's execution state
 463          */
 464         estate->es_range_table = rangeTable;
 465
 466         /*
 467          * if there is a result relation, initialize result relation stuff
 468          */
 469         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 470         {
 471                 List       *resultRelations = parseTree->resultRelations;
 472                 int                     numResultRelations;
 473                 ResultRelInfo *resultRelInfos;
 474
 475                 if (resultRelations != NIL)
 476                 {
 477                         /*
 478                          * Multiple result relations (due to inheritance)
 479                          * parseTree->resultRelations identifies them all
 480                          */
 481                         ResultRelInfo *resultRelInfo;
 482
 483                         numResultRelations = length(resultRelations);
 484                         resultRelInfos = (ResultRelInfo *)
 485                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 486                         resultRelInfo = resultRelInfos;
 487                         while (resultRelations != NIL)
 488                         {
 489                                 initResultRelInfo(resultRelInfo,
 490                                                                   lfirsti(resultRelations),
 491                                                                   rangeTable,
 492                                                                   operation);
 493                                 resultRelInfo++;
 494                                 resultRelations = lnext(resultRelations);
 495                         }
 496                 }
 497                 else
 498                 {
 499                         /*
 500                          * Single result relation identified by
 501                          * parseTree->resultRelation
 502                          */
 503                         numResultRelations = 1;
 504                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 505                         initResultRelInfo(resultRelInfos,
 506                                                           parseTree->resultRelation,
 507                                                           rangeTable,
 508                                                           operation);
 509                 }
 510
 511                 estate->es_result_relations = resultRelInfos;
 512                 estate->es_num_result_relations = numResultRelations;
 513                 /* Initialize to first or only result rel */
 514                 estate->es_result_relation_info = resultRelInfos;
 515         }
 516         else
 517         {
 518                 /*
 519                  * if no result relation, then set state appropriately
 520                  */
 521                 estate->es_result_relations = NULL;
 522                 estate->es_num_result_relations = 0;
 523                 estate->es_result_relation_info = NULL;
 524         }
 525
 526         /*
 527          * Have to lock relations selected for update
 528          */
 529         estate->es_rowMark = NIL;
 530         if (parseTree->rowMarks != NIL)
 531         {
 532                 List       *l;
 533
 534                 foreach(l, parseTree->rowMarks)
 535                 {
 536                         Index           rti = lfirsti(l);
 537                         Oid                     relid = getrelid(rti, rangeTable);
 538                         Relation        relation;
 539                         execRowMark *erm;
 540
 541                         relation = heap_open(relid, RowShareLock);
 542                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 543                         erm->relation = relation;
 544                         erm->rti = rti;
 545                         snprintf(erm->resname, 32, "ctid%u", rti);
 546                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 547                 }
 548         }
 549
 550         /*
 551          * initialize the executor "tuple" table.  We need slots for all the
 552          * plan nodes, plus possibly output slots for the junkfilter(s). At
 553          * this point we aren't sure if we need junkfilters, so just add slots
 554          * for them unconditionally.
 555          */
 556         {
 557                 int                     nSlots = ExecCountSlotsNode(plan);
 558
 559                 if (parseTree->resultRelations != NIL)
 560                         nSlots += length(parseTree->resultRelations);
 561                 else
 562                         nSlots += 1;
 563                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 564         }
 565
 566         /* mark EvalPlanQual not active */
 567         estate->es_origPlan = plan;
 568         estate->es_evalPlanQual = NULL;
 569         estate->es_evTuple = NULL;
 570         estate->es_evTupleNull = NULL;
 571         estate->es_useEvalPlan = false;
 572
 573         /*
 574          * initialize the private state information for all the nodes in the
 575          * query tree.  This opens files, allocates storage and leaves us
 576          * ready to start processing tuples.
 577          */
 578         ExecInitNode(plan, estate, NULL);
 579
 580         /*
 581          * Get the tuple descriptor describing the type of tuples to return.
 582          * (this is especially important if we are creating a relation with
 583          * "SELECT INTO")
 584          */
 585         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 586
 587         /*
 588          * Initialize the junk filter if needed. SELECT and INSERT queries
 589          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 590          * DELETE always need one, since there's always a junk 'ctid'
 591          * attribute present --- no need to look first.
 592          */
 593         {
 594                 bool            junk_filter_needed = false;
 595                 List       *tlist;
 596
 597                 switch (operation)
 598                 {
 599                         case CMD_SELECT:
 600                         case CMD_INSERT:
 601                                 foreach(tlist, plan->targetlist)
 602                                 {
 603                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 604
 605                                         if (tle->resdom->resjunk)
 606                                         {
 607                                                 junk_filter_needed = true;
 608                                                 break;
 609                                         }
 610                                 }
 611                                 break;
 612                         case CMD_UPDATE:
 613                         case CMD_DELETE:
 614                                 junk_filter_needed = true;
 615                                 break;
 616                         default:
 617                                 break;
 618                 }
 619
 620                 if (junk_filter_needed)
 621                 {
 622                         /*
 623                          * If there are multiple result relations, each one needs its
 624                          * own junk filter.  Note this is only possible for
 625                          * UPDATE/DELETE, so we can't be fooled by some needing a
 626                          * filter and some not.
 627                          */
 628                         if (parseTree->resultRelations != NIL)
 629                         {
 630                                 List       *subplans;
 631                                 ResultRelInfo *resultRelInfo;
 632
 633                                 /* Top plan had better be an Append here. */
 634                                 Assert(IsA(plan, Append));
 635                                 Assert(((Append *) plan)->isTarget);
 636                                 subplans = ((Append *) plan)->appendplans;
 637                                 Assert(length(subplans) == estate->es_num_result_relations);
 638                                 resultRelInfo = estate->es_result_relations;
 639                                 while (subplans != NIL)
 640                                 {
 641                                         Plan       *subplan = (Plan *) lfirst(subplans);
 642                                         JunkFilter *j;
 643
 644                                         j = ExecInitJunkFilter(subplan->targetlist,
 645                                                                                    ExecGetTupType(subplan),
 646                                                           ExecAllocTableSlot(estate->es_tupleTable));
 647                                         resultRelInfo->ri_junkFilter = j;
 648                                         resultRelInfo++;
 649                                         subplans = lnext(subplans);
 650                                 }
 651
 652                                 /*
 653                                  * Set active junkfilter too; at this point ExecInitAppend
 654                                  * has already selected an active result relation...
 655                                  */
 656                                 estate->es_junkFilter =
 657                                         estate->es_result_relation_info->ri_junkFilter;
 658                         }
 659                         else
 660                         {
 661                                 /* Normal case with just one JunkFilter */
 662                                 JunkFilter *j;
 663
 664                                 j = ExecInitJunkFilter(plan->targetlist,
 665                                                                            tupType,
 666                                                           ExecAllocTableSlot(estate->es_tupleTable));
 667                                 estate->es_junkFilter = j;
 668                                 if (estate->es_result_relation_info)
 669                                         estate->es_result_relation_info->ri_junkFilter = j;
 670
 671                                 /* For SELECT, want to return the cleaned tuple type */
 672                                 if (operation == CMD_SELECT)
 673                                         tupType = j->jf_cleanTupType;
 674                         }
 675                 }
 676                 else
 677                         estate->es_junkFilter = NULL;
 678         }
 679
 680         /*
 681          * initialize the "into" relation
 682          */
 683         intoRelationDesc = (Relation) NULL;
 684
 685         if (operation == CMD_SELECT)
 686         {
 687                 if (!parseTree->isPortal)
 688                 {
 689                         /*
 690                          * a select into table --- need to create the "into" table
 691                          */
 692                         if (parseTree->into != NULL)
 693                         {
 694                                 char       *intoName;
 695                                 Oid                     namespaceId;
 696                                 AclResult       aclresult;
 697                                 Oid                     intoRelationId;
 698                                 TupleDesc       tupdesc;
 699
 700                                 /*
 701                                  * find namespace to create in, check permissions
 702                                  */
 703                                 intoName = parseTree->into->relname;
 704                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 705
 706                                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 707                                                                                                   ACL_CREATE);
 708                                 if (aclresult != ACLCHECK_OK)
 709                                         aclcheck_error(aclresult,
 710                                                                    get_namespace_name(namespaceId));
 711
 712                                 /*
 713                                  * have to copy tupType to get rid of constraints
 714                                  */
 715                                 tupdesc = CreateTupleDescCopy(tupType);
 716
 717                                 /*
 718                                  * Formerly we forced the output table to have OIDs, but
 719                                  * as of 7.3 it will not have OIDs, because it's too late
 720                                  * here to change the tupdescs of the already-initialized
 721                                  * plan tree.  (Perhaps we could recurse and change them
 722                                  * all, but it's not really worth the trouble IMHO...)
 723                                  */
 724
 725                                 intoRelationId =
 726                                         heap_create_with_catalog(intoName,
 727                                                                                          namespaceId,
 728                                                                                          tupdesc,
 729                                                                                          RELKIND_RELATION,
 730                                                                                          false,
 731                                                                                          ONCOMMIT_NOOP,
 732                                                                                          allowSystemTableMods);
 733
 734                                 FreeTupleDesc(tupdesc);
 735
 736                                 /*
 737                                  * Advance command counter so that the newly-created
 738                                  * relation's catalog tuples will be visible to heap_open.
 739                                  */
 740                                 CommandCounterIncrement();
 741
 742                                 /*
 743                                  * If necessary, create a TOAST table for the into
 744                                  * relation. Note that AlterTableCreateToastTable ends
 745                                  * with CommandCounterIncrement(), so that the TOAST table
 746                                  * will be visible for insertion.
 747                                  */
 748                                 AlterTableCreateToastTable(intoRelationId, true);
 749
 750                                 intoRelationDesc = heap_open(intoRelationId,
 751                                                                                          AccessExclusiveLock);
 752                         }
 753                 }
 754         }
 755
 756         estate->es_into_relation_descriptor = intoRelationDesc;
 757
 758         return tupType;
 759 }
 760
 761 /*
 762  * Initialize ResultRelInfo data for one result relation
 763  */
 764 static void
 765 initResultRelInfo(ResultRelInfo *resultRelInfo,
 766                                   Index resultRelationIndex,
 767                                   List *rangeTable,
 768                                   CmdType operation)
 769 {
 770         Oid                     resultRelationOid;
 771         Relation        resultRelationDesc;
 772
 773         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 774         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 775
 776         switch (resultRelationDesc->rd_rel->relkind)
 777         {
 778                 case RELKIND_SEQUENCE:
 779                         elog(ERROR, "You can't change sequence relation %s",
 780                                  RelationGetRelationName(resultRelationDesc));
 781                         break;
 782                 case RELKIND_TOASTVALUE:
 783                         elog(ERROR, "You can't change toast relation %s",
 784                                  RelationGetRelationName(resultRelationDesc));
 785                         break;
 786                 case RELKIND_VIEW:
 787                         elog(ERROR, "You can't change view relation %s",
 788                                  RelationGetRelationName(resultRelationDesc));
 789                         break;
 790         }
 791
 792         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 793         resultRelInfo->type = T_ResultRelInfo;
 794         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 795         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 796         resultRelInfo->ri_NumIndices = 0;
 797         resultRelInfo->ri_IndexRelationDescs = NULL;
 798         resultRelInfo->ri_IndexRelationInfo = NULL;
 799         /* make a copy so as not to depend on relcache info not changing... */
 800         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 801         resultRelInfo->ri_TrigFunctions = NULL;
 802         resultRelInfo->ri_ConstraintExprs = NULL;
 803         resultRelInfo->ri_junkFilter = NULL;
 804
 805         /*
 806          * If there are indices on the result relation, open them and save
 807          * descriptors in the result relation info, so that we can add new
 808          * index entries for the tuples we add/update.  We need not do this
 809          * for a DELETE, however, since deletion doesn't affect indexes.
 810          */
 811         if (resultRelationDesc->rd_rel->relhasindex &&
 812                 operation != CMD_DELETE)
 813                 ExecOpenIndices(resultRelInfo);
 814 }
 815
 816 /* ----------------------------------------------------------------
 817  *              EndPlan
 818  *
 819  *              Cleans up the query plan -- closes files and free up storages
 820  * ----------------------------------------------------------------
 821  */
 822 static void
 823 EndPlan(Plan *plan, EState *estate)
 824 {
 825         ResultRelInfo *resultRelInfo;
 826         int                     i;
 827         List       *l;
 828
 829         /*
 830          * shut down any PlanQual processing we were doing
 831          */
 832         if (estate->es_evalPlanQual != NULL)
 833                 EndEvalPlanQual(estate);
 834
 835         /*
 836          * shut down the node-type-specific query processing
 837          */
 838         ExecEndNode(plan, NULL);
 839
 840         /*
 841          * destroy the executor "tuple" table.
 842          */
 843         ExecDropTupleTable(estate->es_tupleTable, true);
 844         estate->es_tupleTable = NULL;
 845
 846         /*
 847          * close the result relation(s) if any, but hold locks until xact
 848          * commit.      Also clean up junkfilters if present.
 849          */
 850         resultRelInfo = estate->es_result_relations;
 851         for (i = estate->es_num_result_relations; i > 0; i--)
 852         {
 853                 /* Close indices and then the relation itself */
 854                 ExecCloseIndices(resultRelInfo);
 855                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 856                 /* Delete the junkfilter if any */
 857                 if (resultRelInfo->ri_junkFilter != NULL)
 858                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 859                 resultRelInfo++;
 860         }
 861
 862         /*
 863          * close the "into" relation if necessary, again keeping lock
 864          */
 865         if (estate->es_into_relation_descriptor != NULL)
 866                 heap_close(estate->es_into_relation_descriptor, NoLock);
 867
 868         /*
 869          * There might be a junkfilter without a result relation.
 870          */
 871         if (estate->es_num_result_relations == 0 &&
 872                 estate->es_junkFilter != NULL)
 873         {
 874                 ExecFreeJunkFilter(estate->es_junkFilter);
 875                 estate->es_junkFilter = NULL;
 876         }
 877
 878         /*
 879          * close any relations selected FOR UPDATE, again keeping locks
 880          */
 881         foreach(l, estate->es_rowMark)
 882         {
 883                 execRowMark *erm = lfirst(l);
 884
 885                 heap_close(erm->relation, NoLock);
 886         }
 887 }
 888
 889 /* ----------------------------------------------------------------
 890  *              ExecutePlan
 891  *
 892  *              processes the query plan to retrieve 'numberTuples' tuples in the
 893  *              direction specified.
 894  *              Retrieves all tuples if numberTuples is 0
 895  *
 896  *              result is either a slot containing the last tuple in the case
 897  *              of a SELECT or NULL otherwise.
 898  *
 899  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 900  * user can see it
 901  * ----------------------------------------------------------------
 902  */
 903 static TupleTableSlot *
 904 ExecutePlan(EState *estate,
 905                         Plan *plan,
 906                         CmdType operation,
 907                         long numberTuples,
 908                         ScanDirection direction,
 909                         DestReceiver *destfunc)
 910 {
 911         JunkFilter                      *junkfilter;
 912         TupleTableSlot          *slot;
 913         ItemPointer                      tupleid = NULL;
 914         ItemPointerData          tuple_ctid;
 915         long                             current_tuple_count;
 916         TupleTableSlot          *result;
 917
 918         /*
 919          * initialize local variables
 920          */
 921         slot = NULL;
 922         current_tuple_count = 0;
 923         result = NULL;
 924
 925         /*
 926          * Set the direction.
 927          */
 928         estate->es_direction = direction;
 929
 930         /*
 931          * Process BEFORE EACH STATEMENT triggers
 932          */
 933         switch (operation)
 934         {
 935                 case CMD_UPDATE:
 936                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 937                         break;
 938                 case CMD_DELETE:
 939                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 940                         break;
 941                 case CMD_INSERT:
 942                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 943                         break;
 944                 default:
 945                         /* do nothing */
 946                         break;
 947         }
 948
 949         /*
 950          * Loop until we've processed the proper number of tuples from the
 951          * plan.
 952          */
 953
 954         for (;;)
 955         {
 956                 /* Reset the per-output-tuple exprcontext */
 957                 ResetPerTupleExprContext(estate);
 958
 959                 /*
 960                  * Execute the plan and obtain a tuple
 961                  */
 962 lnext:  ;
 963                 if (estate->es_useEvalPlan)
 964                 {
 965                         slot = EvalPlanQualNext(estate);
 966                         if (TupIsNull(slot))
 967                                 slot = ExecProcNode(plan, NULL);
 968                 }
 969                 else
 970                         slot = ExecProcNode(plan, NULL);
 971
 972                 /*
 973                  * if the tuple is null, then we assume there is nothing more to
 974                  * process so we just return null...
 975                  */
 976                 if (TupIsNull(slot))
 977                 {
 978                         result = NULL;
 979                         break;
 980                 }
 981
 982                 /*
 983                  * if we have a junk filter, then project a new tuple with the
 984                  * junk removed.
 985                  *
 986                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 987                  * (Formerly, we stored it back over the "dirty" tuple, which is
 988                  * WRONG because that tuple slot has the wrong descriptor.)
 989                  *
 990                  * Also, extract all the junk information we need.
 991                  */
 992                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 993                 {
 994                         Datum           datum;
 995                         HeapTuple       newTuple;
 996                         bool            isNull;
 997
 998                         /*
 999                          * extract the 'ctid' junk attribute.
1000                          */
1001                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1002                         {
1003                                 if (!ExecGetJunkAttribute(junkfilter,
1004                                                                                   slot,
1005                                                                                   "ctid",
1006                                                                                   &datum,
1007                                                                                   &isNull))
1008                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1009
1010                                 /* shouldn't ever get a null result... */
1011                                 if (isNull)
1012                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1013
1014                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1015                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1016                                                                                  * ctid!! */
1017                                 tupleid = &tuple_ctid;
1018                         }
1019                         else if (estate->es_rowMark != NIL)
1020                         {
1021                                 List       *l;
1022
1023                 lmark:  ;
1024                                 foreach(l, estate->es_rowMark)
1025                                 {
1026                                         execRowMark *erm = lfirst(l);
1027                                         Buffer          buffer;
1028                                         HeapTupleData tuple;
1029                                         TupleTableSlot *newSlot;
1030                                         int                     test;
1031
1032                                         if (!ExecGetJunkAttribute(junkfilter,
1033                                                                                           slot,
1034                                                                                           erm->resname,
1035                                                                                           &datum,
1036                                                                                           &isNull))
1037                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1038                                                          erm->resname);
1039
1040                                         /* shouldn't ever get a null result... */
1041                                         if (isNull)
1042                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1043                                                          erm->resname);
1044
1045                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1046                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1047                                                                                         estate->es_snapshot->curcid);
1048                                         ReleaseBuffer(buffer);
1049                                         switch (test)
1050                                         {
1051                                                 case HeapTupleSelfUpdated:
1052                                                         /* treat it as deleted; do not process */
1053                                                         goto lnext;
1054
1055                                                 case HeapTupleMayBeUpdated:
1056                                                         break;
1057
1058                                                 case HeapTupleUpdated:
1059                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1060                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1061                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1062                                                                   (ItemPointer) DatumGetPointer(datum))))
1063                                                         {
1064                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1065                                                                 if (!(TupIsNull(newSlot)))
1066                                                                 {
1067                                                                         slot = newSlot;
1068                                                                         estate->es_useEvalPlan = true;
1069                                                                         goto lmark;
1070                                                                 }
1071                                                         }
1072
1073                                                         /*
1074                                                          * if tuple was deleted or PlanQual failed for
1075                                                          * updated tuple - we must not return this
1076                                                          * tuple!
1077                                                          */
1078                                                         goto lnext;
1079
1080                                                 default:
1081                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1082                                                         return (NULL);
1083                                         }
1084                                 }
1085                         }
1086
1087                         /*
1088                          * Finally create a new "clean" tuple with all junk attributes
1089                          * removed
1090                          */
1091                         newTuple = ExecRemoveJunk(junkfilter, slot);
1092
1093                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1094                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1095                                                                   InvalidBuffer,                /* this tuple has no
1096                                                                                                                  * buffer */
1097                                                                   true);                /* tuple should be pfreed */
1098                 }
1099
1100                 /*
1101                  * now that we have a tuple, do the appropriate thing with it..
1102                  * either return it to the user, add it to a relation someplace,
1103                  * delete it from a relation, or modify some of its attributes.
1104                  */
1105                 switch (operation)
1106                 {
1107                         case CMD_SELECT:
1108                                 ExecSelect(slot,        /* slot containing tuple */
1109                                                    destfunc,    /* destination's tuple-receiver
1110                                                                                  * obj */
1111                                                    estate);
1112                                 result = slot;
1113                                 break;
1114
1115                         case CMD_INSERT:
1116                                 ExecInsert(slot, tupleid, estate);
1117                                 result = NULL;
1118                                 break;
1119
1120                         case CMD_DELETE:
1121                                 ExecDelete(slot, tupleid, estate);
1122                                 result = NULL;
1123                                 break;
1124
1125                         case CMD_UPDATE:
1126                                 ExecUpdate(slot, tupleid, estate);
1127                                 result = NULL;
1128                                 break;
1129
1130                         default:
1131                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1132                                 result = NULL;
1133                                 break;
1134                 }
1135
1136                 /*
1137                  * check our tuple count.. if we've processed the proper number
1138                  * then quit, else loop again and process more tuples.  Zero
1139                  * number_tuples means no limit.
1140                  */
1141                 current_tuple_count++;
1142                 if (numberTuples == current_tuple_count)
1143                         break;
1144         }
1145
1146         /*
1147          * Process AFTER EACH STATEMENT triggers
1148          */
1149         switch (operation)
1150         {
1151                 case CMD_UPDATE:
1152                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1153                         break;
1154                 case CMD_DELETE:
1155                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1156                         break;
1157                 case CMD_INSERT:
1158                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1159                         break;
1160                 default:
1161                         /* do nothing */
1162                         break;
1163         }
1164
1165         /*
1166          * here, result is either a slot containing a tuple in the case of a
1167          * SELECT or NULL otherwise.
1168          */
1169         return result;
1170 }
1171
1172 /* ----------------------------------------------------------------
1173  *              ExecSelect
1174  *
1175  *              SELECTs are easy.. we just pass the tuple to the appropriate
1176  *              print function.  The only complexity is when we do a
1177  *              "SELECT INTO", in which case we insert the tuple into
1178  *              the appropriate relation (note: this is a newly created relation
1179  *              so we don't need to worry about indices or locks.)
1180  * ----------------------------------------------------------------
1181  */
1182 static void
1183 ExecSelect(TupleTableSlot *slot,
1184                    DestReceiver *destfunc,
1185                    EState *estate)
1186 {
1187         HeapTuple       tuple;
1188         TupleDesc       attrtype;
1189
1190         /*
1191          * get the heap tuple out of the tuple table slot
1192          */
1193         tuple = slot->val;
1194         attrtype = slot->ttc_tupleDescriptor;
1195
1196         /*
1197          * insert the tuple into the "into relation"
1198          */
1199         if (estate->es_into_relation_descriptor != NULL)
1200         {
1201                 heap_insert(estate->es_into_relation_descriptor, tuple,
1202                                         estate->es_snapshot->curcid);
1203                 IncrAppended();
1204         }
1205
1206         /*
1207          * send the tuple to the front end (or the screen)
1208          */
1209         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1210         IncrRetrieved();
1211         (estate->es_processed)++;
1212 }
1213
1214 /* ----------------------------------------------------------------
1215  *              ExecInsert
1216  *
1217  *              INSERTs are trickier.. we have to insert the tuple into
1218  *              the base relation and insert appropriate tuples into the
1219  *              index relations.
1220  * ----------------------------------------------------------------
1221  */
1222 static void
1223 ExecInsert(TupleTableSlot *slot,
1224                    ItemPointer tupleid,
1225                    EState *estate)
1226 {
1227         HeapTuple       tuple;
1228         ResultRelInfo *resultRelInfo;
1229         Relation        resultRelationDesc;
1230         int                     numIndices;
1231         Oid                     newId;
1232
1233         /*
1234          * get the heap tuple out of the tuple table slot
1235          */
1236         tuple = slot->val;
1237
1238         /*
1239          * get information on the (current) result relation
1240          */
1241         resultRelInfo = estate->es_result_relation_info;
1242         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1243
1244         /* BEFORE ROW INSERT Triggers */
1245         if (resultRelInfo->ri_TrigDesc &&
1246                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1247         {
1248                 HeapTuple       newtuple;
1249
1250                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1251
1252                 if (newtuple == NULL)   /* "do nothing" */
1253                         return;
1254
1255                 if (newtuple != tuple)  /* modified by Trigger(s) */
1256                 {
1257                         /*
1258                          * Insert modified tuple into tuple table slot, replacing the
1259                          * original.  We assume that it was allocated in per-tuple
1260                          * memory context, and therefore will go away by itself. The
1261                          * tuple table slot should not try to clear it.
1262                          */
1263                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1264                         tuple = newtuple;
1265                 }
1266         }
1267
1268         /*
1269          * Check the constraints of the tuple
1270          */
1271         if (resultRelationDesc->rd_att->constr)
1272                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1273
1274         /*
1275          * insert the tuple
1276          */
1277         newId = heap_insert(resultRelationDesc, tuple,
1278                                                 estate->es_snapshot->curcid);
1279
1280         IncrAppended();
1281         (estate->es_processed)++;
1282         estate->es_lastoid = newId;
1283         setLastTid(&(tuple->t_self));
1284
1285         /*
1286          * process indices
1287          *
1288          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1289          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1290          * field.
1291          */
1292         numIndices = resultRelInfo->ri_NumIndices;
1293         if (numIndices > 0)
1294                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1295
1296         /* AFTER ROW INSERT Triggers */
1297         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1298 }
1299
1300 /* ----------------------------------------------------------------
1301  *              ExecDelete
1302  *
1303  *              DELETE is like UPDATE, we delete the tuple and its
1304  *              index tuples.
1305  * ----------------------------------------------------------------
1306  */
1307 static void
1308 ExecDelete(TupleTableSlot *slot,
1309                    ItemPointer tupleid,
1310                    EState *estate)
1311 {
1312         ResultRelInfo *resultRelInfo;
1313         Relation        resultRelationDesc;
1314         ItemPointerData ctid;
1315         int                     result;
1316
1317         /*
1318          * get information on the (current) result relation
1319          */
1320         resultRelInfo = estate->es_result_relation_info;
1321         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1322
1323         /* BEFORE ROW DELETE Triggers */
1324         if (resultRelInfo->ri_TrigDesc &&
1325           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1326         {
1327                 bool            dodelete;
1328
1329                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1330
1331                 if (!dodelete)                  /* "do nothing" */
1332                         return;
1333         }
1334
1335         /*
1336          * delete the tuple
1337          */
1338 ldelete:;
1339         result = heap_delete(resultRelationDesc, tupleid,
1340                                                  &ctid,
1341                                                  estate->es_snapshot->curcid);
1342         switch (result)
1343         {
1344                 case HeapTupleSelfUpdated:
1345                         /* already deleted by self; nothing to do */
1346                         return;
1347
1348                 case HeapTupleMayBeUpdated:
1349                         break;
1350
1351                 case HeapTupleUpdated:
1352                         if (XactIsoLevel == XACT_SERIALIZABLE)
1353                                 elog(ERROR, "Can't serialize access due to concurrent update");
1354                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1355                         {
1356                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1357                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1358
1359                                 if (!TupIsNull(epqslot))
1360                                 {
1361                                         *tupleid = ctid;
1362                                         goto ldelete;
1363                                 }
1364                         }
1365                         /* tuple already deleted; nothing to do */
1366                         return;
1367
1368                 default:
1369                         elog(ERROR, "Unknown status %u from heap_delete", result);
1370                         return;
1371         }
1372
1373         IncrDeleted();
1374         (estate->es_processed)++;
1375
1376         /*
1377          * Note: Normally one would think that we have to delete index tuples
1378          * associated with the heap tuple now..
1379          *
1380          * ... but in POSTGRES, we have no need to do this because the vacuum
1381          * daemon automatically opens an index scan and deletes index tuples
1382          * when it finds deleted heap tuples. -cim 9/27/89
1383          */
1384
1385         /* AFTER ROW DELETE Triggers */
1386         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1387 }
1388
1389 /* ----------------------------------------------------------------
1390  *              ExecUpdate
1391  *
1392  *              note: we can't run UPDATE queries with transactions
1393  *              off because UPDATEs are actually INSERTs and our
1394  *              scan will mistakenly loop forever, updating the tuple
1395  *              it just inserted..      This should be fixed but until it
1396  *              is, we don't want to get stuck in an infinite loop
1397  *              which corrupts your database..
1398  * ----------------------------------------------------------------
1399  */
1400 static void
1401 ExecUpdate(TupleTableSlot *slot,
1402                    ItemPointer tupleid,
1403                    EState *estate)
1404 {
1405         HeapTuple       tuple;
1406         ResultRelInfo *resultRelInfo;
1407         Relation        resultRelationDesc;
1408         ItemPointerData ctid;
1409         int                     result;
1410         int                     numIndices;
1411
1412         /*
1413          * abort the operation if not running transactions
1414          */
1415         if (IsBootstrapProcessingMode())
1416         {
1417                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1418                 return;
1419         }
1420
1421         /*
1422          * get the heap tuple out of the tuple table slot
1423          */
1424         tuple = slot->val;
1425
1426         /*
1427          * get information on the (current) result relation
1428          */
1429         resultRelInfo = estate->es_result_relation_info;
1430         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1431
1432         /* BEFORE ROW UPDATE Triggers */
1433         if (resultRelInfo->ri_TrigDesc &&
1434           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1435         {
1436                 HeapTuple       newtuple;
1437
1438                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1439                                                                                 tupleid, tuple);
1440
1441                 if (newtuple == NULL)   /* "do nothing" */
1442                         return;
1443
1444                 if (newtuple != tuple)  /* modified by Trigger(s) */
1445                 {
1446                         /*
1447                          * Insert modified tuple into tuple table slot, replacing the
1448                          * original.  We assume that it was allocated in per-tuple
1449                          * memory context, and therefore will go away by itself. The
1450                          * tuple table slot should not try to clear it.
1451                          */
1452                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1453                         tuple = newtuple;
1454                 }
1455         }
1456
1457         /*
1458          * Check the constraints of the tuple
1459          *
1460          * If we generate a new candidate tuple after EvalPlanQual testing, we
1461          * must loop back here and recheck constraints.  (We don't need to
1462          * redo triggers, however.      If there are any BEFORE triggers then
1463          * trigger.c will have done mark4update to lock the correct tuple, so
1464          * there's no need to do them again.)
1465          */
1466 lreplace:;
1467         if (resultRelationDesc->rd_att->constr)
1468                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1469
1470         /*
1471          * replace the heap tuple
1472          */
1473         result = heap_update(resultRelationDesc, tupleid, tuple,
1474                                                  &ctid,
1475                                                  estate->es_snapshot->curcid);
1476         switch (result)
1477         {
1478                 case HeapTupleSelfUpdated:
1479                         /* already deleted by self; nothing to do */
1480                         return;
1481
1482                 case HeapTupleMayBeUpdated:
1483                         break;
1484
1485                 case HeapTupleUpdated:
1486                         if (XactIsoLevel == XACT_SERIALIZABLE)
1487                                 elog(ERROR, "Can't serialize access due to concurrent update");
1488                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1489                         {
1490                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1491                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1492
1493                                 if (!TupIsNull(epqslot))
1494                                 {
1495                                         *tupleid = ctid;
1496                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1497                                         slot = ExecStoreTuple(tuple,
1498                                                                         estate->es_junkFilter->jf_resultSlot,
1499                                                                                   InvalidBuffer, true);
1500                                         goto lreplace;
1501                                 }
1502                         }
1503                         /* tuple already deleted; nothing to do */
1504                         return;
1505
1506                 default:
1507                         elog(ERROR, "Unknown status %u from heap_update", result);
1508                         return;
1509         }
1510
1511         IncrReplaced();
1512         (estate->es_processed)++;
1513
1514         /*
1515          * Note: instead of having to update the old index tuples associated
1516          * with the heap tuple, all we do is form and insert new index tuples.
1517          * This is because UPDATEs are actually DELETEs and INSERTs and index
1518          * tuple deletion is done automagically by the vacuum daemon. All we
1519          * do is insert new index tuples.  -cim 9/27/89
1520          */
1521
1522         /*
1523          * process indices
1524          *
1525          * heap_update updates a tuple in the base relation by invalidating it
1526          * and then inserting a new tuple to the relation.      As a side effect,
1527          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1528          * field.  So we now insert index tuples using the new tupleid stored
1529          * there.
1530          */
1531
1532         numIndices = resultRelInfo->ri_NumIndices;
1533         if (numIndices > 0)
1534                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1535
1536         /* AFTER ROW UPDATE Triggers */
1537         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1538 }
1539
1540 static char *
1541 ExecRelCheck(ResultRelInfo *resultRelInfo,
1542                          TupleTableSlot *slot, EState *estate)
1543 {
1544         Relation        rel = resultRelInfo->ri_RelationDesc;
1545         int                     ncheck = rel->rd_att->constr->num_check;
1546         ConstrCheck *check = rel->rd_att->constr->check;
1547         ExprContext *econtext;
1548         MemoryContext oldContext;
1549         List       *qual;
1550         int                     i;
1551
1552         /*
1553          * If first time through for this result relation, build expression
1554          * nodetrees for rel's constraint expressions.  Keep them in the
1555          * per-query memory context so they'll survive throughout the query.
1556          */
1557         if (resultRelInfo->ri_ConstraintExprs == NULL)
1558         {
1559                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1560                 resultRelInfo->ri_ConstraintExprs =
1561                         (List **) palloc(ncheck * sizeof(List *));
1562                 for (i = 0; i < ncheck; i++)
1563                 {
1564                         qual = (List *) stringToNode(check[i].ccbin);
1565                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1566                 }
1567                 MemoryContextSwitchTo(oldContext);
1568         }
1569
1570         /*
1571          * We will use the EState's per-tuple context for evaluating
1572          * constraint expressions (creating it if it's not already there).
1573          */
1574         econtext = GetPerTupleExprContext(estate);
1575
1576         /* Arrange for econtext's scan tuple to be the tuple under test */
1577         econtext->ecxt_scantuple = slot;
1578
1579         /* And evaluate the constraints */
1580         for (i = 0; i < ncheck; i++)
1581         {
1582                 qual = resultRelInfo->ri_ConstraintExprs[i];
1583
1584                 /*
1585                  * NOTE: SQL92 specifies that a NULL result from a constraint
1586                  * expression is not to be treated as a failure.  Therefore, tell
1587                  * ExecQual to return TRUE for NULL.
1588                  */
1589                 if (!ExecQual(qual, econtext, true))
1590                         return check[i].ccname;
1591         }
1592
1593         /* NULL result means no error */
1594         return (char *) NULL;
1595 }
1596
1597 void
1598 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1599                                 TupleTableSlot *slot, EState *estate)
1600 {
1601         Relation        rel = resultRelInfo->ri_RelationDesc;
1602         HeapTuple       tuple = slot->val;
1603         TupleConstr *constr = rel->rd_att->constr;
1604
1605         Assert(constr);
1606
1607         if (constr->has_not_null)
1608         {
1609                 int                     natts = rel->rd_att->natts;
1610                 int                     attrChk;
1611
1612                 for (attrChk = 1; attrChk <= natts; attrChk++)
1613                 {
1614                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1615                                 heap_attisnull(tuple, attrChk))
1616                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1617                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1618                 }
1619         }
1620
1621         if (constr->num_check > 0)
1622         {
1623                 char       *failed;
1624
1625                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1626                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1627                                  caller, failed, RelationGetRelationName(rel));
1628         }
1629 }
1630
1631 /*
1632  * Check a modified tuple to see if we want to process its updated version
1633  * under READ COMMITTED rules.
1634  *
1635  * See backend/executor/README for some info about how this works.
1636  */
1637 TupleTableSlot *
1638 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1639 {
1640         evalPlanQual *epq;
1641         EState     *epqstate;
1642         Relation        relation;
1643         HeapTupleData tuple;
1644         HeapTuple       copyTuple = NULL;
1645         int                     rtsize;
1646         bool            endNode;
1647
1648         Assert(rti != 0);
1649
1650         /*
1651          * find relation containing target tuple
1652          */
1653         if (estate->es_result_relation_info != NULL &&
1654                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1655                 relation = estate->es_result_relation_info->ri_RelationDesc;
1656         else
1657         {
1658                 List       *l;
1659
1660                 relation = NULL;
1661                 foreach(l, estate->es_rowMark)
1662                 {
1663                         if (((execRowMark *) lfirst(l))->rti == rti)
1664                         {
1665                                 relation = ((execRowMark *) lfirst(l))->relation;
1666                                 break;
1667                         }
1668                 }
1669                 if (relation == NULL)
1670                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1671         }
1672
1673         /*
1674          * fetch tid tuple
1675          *
1676          * Loop here to deal with updated or busy tuples
1677          */
1678         tuple.t_self = *tid;
1679         for (;;)
1680         {
1681                 Buffer          buffer;
1682
1683                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1684                 {
1685                         TransactionId xwait = SnapshotDirty->xmax;
1686
1687                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1688                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1689
1690                         /*
1691                          * If tuple is being updated by other transaction then we have
1692                          * to wait for its commit/abort.
1693                          */
1694                         if (TransactionIdIsValid(xwait))
1695                         {
1696                                 ReleaseBuffer(buffer);
1697                                 XactLockTableWait(xwait);
1698                                 continue;
1699                         }
1700
1701                         /*
1702                          * We got tuple - now copy it for use by recheck query.
1703                          */
1704                         copyTuple = heap_copytuple(&tuple);
1705                         ReleaseBuffer(buffer);
1706                         break;
1707                 }
1708
1709                 /*
1710                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1711                  * Note that it's possible to get invalid SnapshotDirty->tid if
1712                  * tuple updated by this transaction. Have we to check this ?
1713                  */
1714                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1715                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1716                 {
1717                         /* updated, so look at the updated copy */
1718                         tuple.t_self = SnapshotDirty->tid;
1719                         continue;
1720                 }
1721
1722                 /*
1723                  * Deleted or updated by this transaction; forget it.
1724                  */
1725                 return NULL;
1726         }
1727
1728         /*
1729          * For UPDATE/DELETE we have to return tid of actual row we're
1730          * executing PQ for.
1731          */
1732         *tid = tuple.t_self;
1733
1734         /*
1735          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1736          */
1737         epq = (evalPlanQual *) estate->es_evalPlanQual;
1738         rtsize = length(estate->es_range_table);
1739         endNode = true;
1740
1741         if (epq != NULL && epq->rti == 0)
1742         {
1743                 /* Top PQ stack entry is idle, so re-use it */
1744                 Assert(!(estate->es_useEvalPlan) &&
1745                            epq->estate.es_evalPlanQual == NULL);
1746                 epq->rti = rti;
1747                 endNode = false;
1748         }
1749
1750         /*
1751          * If this is request for another RTE - Ra, - then we have to check
1752          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1753          * updated again and we have to re-start old execution for Ra and
1754          * forget all what we done after Ra was suspended. Cool? -:))
1755          */
1756         if (epq != NULL && epq->rti != rti &&
1757                 epq->estate.es_evTuple[rti - 1] != NULL)
1758         {
1759                 do
1760                 {
1761                         evalPlanQual *oldepq;
1762
1763                         /* pop previous PlanQual from the stack */
1764                         epqstate = &(epq->estate);
1765                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1766                         Assert(oldepq->rti != 0);
1767                         /* stop execution */
1768                         ExecEndNode(epq->plan, NULL);
1769                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1770                         epqstate->es_tupleTable = NULL;
1771                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1772                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1773                         /* push current PQ to freePQ stack */
1774                         oldepq->free = epq;
1775                         epq = oldepq;
1776                         estate->es_evalPlanQual = (Pointer) epq;
1777                 } while (epq->rti != rti);
1778         }
1779
1780         /*
1781          * If we are requested for another RTE then we have to suspend
1782          * execution of current PlanQual and start execution for new one.
1783          */
1784         if (epq == NULL || epq->rti != rti)
1785         {
1786                 /* try to reuse plan used previously */
1787                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1788
1789                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1790                 {
1791                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1792                         newepq->free = NULL;
1793
1794                         /*
1795                          * Each stack level has its own copy of the plan tree.  This
1796                          * is wasteful, but necessary as long as plan nodes point to
1797                          * exec state nodes rather than vice versa.  Note that
1798                          * copyfuncs.c doesn't attempt to copy the exec state nodes,
1799                          * which is a good thing in this situation.
1800                          */
1801                         newepq->plan = copyObject(estate->es_origPlan);
1802
1803                         /*
1804                          * Init stack level's EState.  We share top level's copy of
1805                          * es_result_relations array and other non-changing status. We
1806                          * need our own tupletable, es_param_exec_vals, and other
1807                          * changeable state.
1808                          */
1809                         epqstate = &(newepq->estate);
1810                         memcpy(epqstate, estate, sizeof(EState));
1811                         epqstate->es_direction = ForwardScanDirection;
1812                         if (estate->es_origPlan->nParamExec > 0)
1813                                 epqstate->es_param_exec_vals = (ParamExecData *)
1814                                         palloc(estate->es_origPlan->nParamExec *
1815                                                    sizeof(ParamExecData));
1816                         epqstate->es_tupleTable = NULL;
1817                         epqstate->es_per_tuple_exprcontext = NULL;
1818
1819                         /*
1820                          * Each epqstate must have its own es_evTupleNull state, but
1821                          * all the stack entries share es_evTuple state.  This allows
1822                          * sub-rechecks to inherit the value being examined by an
1823                          * outer recheck.
1824                          */
1825                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1826                         if (epq == NULL)
1827                                 /* first PQ stack entry */
1828                                 epqstate->es_evTuple = (HeapTuple *)
1829                                         palloc0(rtsize * sizeof(HeapTuple));
1830                         else
1831                                 /* later stack entries share the same storage */
1832                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1833                 }
1834                 else
1835                 {
1836                         /* recycle previously used EState */
1837                         epqstate = &(newepq->estate);
1838                 }
1839                 /* push current PQ to the stack */
1840                 epqstate->es_evalPlanQual = (Pointer) epq;
1841                 epq = newepq;
1842                 estate->es_evalPlanQual = (Pointer) epq;
1843                 epq->rti = rti;
1844                 endNode = false;
1845         }
1846
1847         Assert(epq->rti == rti);
1848         epqstate = &(epq->estate);
1849
1850         /*
1851          * Ok - we're requested for the same RTE.  Unfortunately we still have
1852          * to end and restart execution of the plan, because ExecReScan
1853          * wouldn't ensure that upper plan nodes would reset themselves.  We
1854          * could make that work if insertion of the target tuple were
1855          * integrated with the Param mechanism somehow, so that the upper plan
1856          * nodes know that their children's outputs have changed.
1857          */
1858         if (endNode)
1859         {
1860                 /* stop execution */
1861                 ExecEndNode(epq->plan, NULL);
1862                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1863                 epqstate->es_tupleTable = NULL;
1864         }
1865
1866         /*
1867          * free old RTE' tuple, if any, and store target tuple where
1868          * relation's scan node will see it
1869          */
1870         if (epqstate->es_evTuple[rti - 1] != NULL)
1871                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1872         epqstate->es_evTuple[rti - 1] = copyTuple;
1873
1874         /*
1875          * Initialize for new recheck query; be careful to copy down state
1876          * that might have changed in top EState.
1877          */
1878         epqstate->es_result_relation_info = estate->es_result_relation_info;
1879         epqstate->es_junkFilter = estate->es_junkFilter;
1880         if (estate->es_origPlan->nParamExec > 0)
1881                 memset(epqstate->es_param_exec_vals, 0,
1882                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1883         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1884         epqstate->es_useEvalPlan = false;
1885         Assert(epqstate->es_tupleTable == NULL);
1886         epqstate->es_tupleTable =
1887                 ExecCreateTupleTable(estate->es_tupleTable->size);
1888
1889         ExecInitNode(epq->plan, epqstate, NULL);
1890
1891         return EvalPlanQualNext(estate);
1892 }
1893
1894 static TupleTableSlot *
1895 EvalPlanQualNext(EState *estate)
1896 {
1897         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1898         EState     *epqstate = &(epq->estate);
1899         evalPlanQual *oldepq;
1900         TupleTableSlot *slot;
1901
1902         Assert(epq->rti != 0);
1903
1904 lpqnext:;
1905         slot = ExecProcNode(epq->plan, NULL);
1906
1907         /*
1908          * No more tuples for this PQ. Continue previous one.
1909          */
1910         if (TupIsNull(slot))
1911         {
1912                 /* stop execution */
1913                 ExecEndNode(epq->plan, NULL);
1914                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1915                 epqstate->es_tupleTable = NULL;
1916                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1917                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1918                 /* pop old PQ from the stack */
1919                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1920                 if (oldepq == (evalPlanQual *) NULL)
1921                 {
1922                         epq->rti = 0;           /* this is the first (oldest) */
1923                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1924                         return (NULL);          /* continue Query execution   */
1925                 }
1926                 Assert(oldepq->rti != 0);
1927                 /* push current PQ to freePQ stack */
1928                 oldepq->free = epq;
1929                 epq = oldepq;
1930                 epqstate = &(epq->estate);
1931                 estate->es_evalPlanQual = (Pointer) epq;
1932                 goto lpqnext;
1933         }
1934
1935         return (slot);
1936 }
1937
1938 static void
1939 EndEvalPlanQual(EState *estate)
1940 {
1941         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1942         EState     *epqstate = &(epq->estate);
1943         evalPlanQual *oldepq;
1944
1945         if (epq->rti == 0)                      /* plans already shutdowned */
1946         {
1947                 Assert(epq->estate.es_evalPlanQual == NULL);
1948                 return;
1949         }
1950
1951         for (;;)
1952         {
1953                 /* stop execution */
1954                 ExecEndNode(epq->plan, NULL);
1955                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1956                 epqstate->es_tupleTable = NULL;
1957                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1958                 {
1959                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1960                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1961                 }
1962                 /* pop old PQ from the stack */
1963                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1964                 if (oldepq == (evalPlanQual *) NULL)
1965                 {
1966                         epq->rti = 0;           /* this is the first (oldest) */
1967                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1968                         break;
1969                 }
1970                 Assert(oldepq->rti != 0);
1971                 /* push current PQ to freePQ stack */
1972                 oldepq->free = epq;
1973                 epq = oldepq;
1974                 epqstate = &(epq->estate);
1975                 estate->es_evalPlanQual = (Pointer) epq;
1976         }
1977 }