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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.187 2002/11/23 03:59:07 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         Oid                     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         }
 947
 948         /*
 949          * Loop until we've processed the proper number of tuples from the
 950          * plan.
 951          */
 952
 953         for (;;)
 954         {
 955                 /* Reset the per-output-tuple exprcontext */
 956                 ResetPerTupleExprContext(estate);
 957
 958                 /*
 959                  * Execute the plan and obtain a tuple
 960                  */
 961 lnext:  ;
 962                 if (estate->es_useEvalPlan)
 963                 {
 964                         slot = EvalPlanQualNext(estate);
 965                         if (TupIsNull(slot))
 966                                 slot = ExecProcNode(plan, NULL);
 967                 }
 968                 else
 969                         slot = ExecProcNode(plan, NULL);
 970
 971                 /*
 972                  * if the tuple is null, then we assume there is nothing more to
 973                  * process so we just return null...
 974                  */
 975                 if (TupIsNull(slot))
 976                 {
 977                         result = NULL;
 978                         break;
 979                 }
 980
 981                 /*
 982                  * if we have a junk filter, then project a new tuple with the
 983                  * junk removed.
 984                  *
 985                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 986                  * (Formerly, we stored it back over the "dirty" tuple, which is
 987                  * WRONG because that tuple slot has the wrong descriptor.)
 988                  *
 989                  * Also, extract all the junk information we need.
 990                  */
 991                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 992                 {
 993                         Datum           datum;
 994                         HeapTuple       newTuple;
 995                         bool            isNull;
 996
 997                         /*
 998                          * extract the 'ctid' junk attribute.
 999                          */
1000                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1001                         {
1002                                 if (!ExecGetJunkAttribute(junkfilter,
1003                                                                                   slot,
1004                                                                                   "ctid",
1005                                                                                   &datum,
1006                                                                                   &isNull))
1007                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1008
1009                                 /* shouldn't ever get a null result... */
1010                                 if (isNull)
1011                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1012
1013                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1014                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1015                                                                                  * ctid!! */
1016                                 tupleid = &tuple_ctid;
1017                         }
1018                         else if (estate->es_rowMark != NIL)
1019                         {
1020                                 List       *l;
1021
1022                 lmark:  ;
1023                                 foreach(l, estate->es_rowMark)
1024                                 {
1025                                         execRowMark *erm = lfirst(l);
1026                                         Buffer          buffer;
1027                                         HeapTupleData tuple;
1028                                         TupleTableSlot *newSlot;
1029                                         int                     test;
1030
1031                                         if (!ExecGetJunkAttribute(junkfilter,
1032                                                                                           slot,
1033                                                                                           erm->resname,
1034                                                                                           &datum,
1035                                                                                           &isNull))
1036                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1037                                                          erm->resname);
1038
1039                                         /* shouldn't ever get a null result... */
1040                                         if (isNull)
1041                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1042                                                          erm->resname);
1043
1044                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1045                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1046                                                                                         estate->es_snapshot->curcid);
1047                                         ReleaseBuffer(buffer);
1048                                         switch (test)
1049                                         {
1050                                                 case HeapTupleSelfUpdated:
1051                                                         /* treat it as deleted; do not process */
1052                                                         goto lnext;
1053
1054                                                 case HeapTupleMayBeUpdated:
1055                                                         break;
1056
1057                                                 case HeapTupleUpdated:
1058                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1059                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1060                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1061                                                                   (ItemPointer) DatumGetPointer(datum))))
1062                                                         {
1063                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1064                                                                 if (!(TupIsNull(newSlot)))
1065                                                                 {
1066                                                                         slot = newSlot;
1067                                                                         estate->es_useEvalPlan = true;
1068                                                                         goto lmark;
1069                                                                 }
1070                                                         }
1071
1072                                                         /*
1073                                                          * if tuple was deleted or PlanQual failed for
1074                                                          * updated tuple - we must not return this
1075                                                          * tuple!
1076                                                          */
1077                                                         goto lnext;
1078
1079                                                 default:
1080                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1081                                                         return (NULL);
1082                                         }
1083                                 }
1084                         }
1085
1086                         /*
1087                          * Finally create a new "clean" tuple with all junk attributes
1088                          * removed
1089                          */
1090                         newTuple = ExecRemoveJunk(junkfilter, slot);
1091
1092                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1093                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1094                                                                   InvalidBuffer,                /* this tuple has no
1095                                                                                                                  * buffer */
1096                                                                   true);                /* tuple should be pfreed */
1097                 }
1098
1099                 /*
1100                  * now that we have a tuple, do the appropriate thing with it..
1101                  * either return it to the user, add it to a relation someplace,
1102                  * delete it from a relation, or modify some of its attributes.
1103                  */
1104                 switch (operation)
1105                 {
1106                         case CMD_SELECT:
1107                                 ExecSelect(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                                 ExecInsert(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                                 ExecUpdate(slot, tupleid, estate);
1126                                 result = NULL;
1127                                 break;
1128
1129                         default:
1130                                 elog(LOG, "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.  Zero
1138                  * number_tuples means no limit.
1139                  */
1140                 current_tuple_count++;
1141                 if (numberTuples == current_tuple_count)
1142                         break;
1143         }
1144
1145         /*
1146          * Process AFTER EACH STATEMENT triggers
1147          */
1148         switch (operation)
1149         {
1150                 case CMD_UPDATE:
1151                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1152                         break;
1153                 case CMD_DELETE:
1154                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1155                         break;
1156                 case CMD_INSERT:
1157                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1158                         break;
1159                 default:
1160                         /* do nothing */
1161         }
1162
1163         /*
1164          * here, result is either a slot containing a tuple in the case of a
1165          * SELECT or NULL otherwise.
1166          */
1167         return result;
1168 }
1169
1170 /* ----------------------------------------------------------------
1171  *              ExecSelect
1172  *
1173  *              SELECTs are easy.. we just pass the tuple to the appropriate
1174  *              print function.  The only complexity is when we do a
1175  *              "SELECT INTO", in which case we insert the tuple into
1176  *              the appropriate relation (note: this is a newly created relation
1177  *              so we don't need to worry about indices or locks.)
1178  * ----------------------------------------------------------------
1179  */
1180 static void
1181 ExecSelect(TupleTableSlot *slot,
1182                    DestReceiver *destfunc,
1183                    EState *estate)
1184 {
1185         HeapTuple       tuple;
1186         TupleDesc       attrtype;
1187
1188         /*
1189          * get the heap tuple out of the tuple table slot
1190          */
1191         tuple = slot->val;
1192         attrtype = slot->ttc_tupleDescriptor;
1193
1194         /*
1195          * insert the tuple into the "into relation"
1196          */
1197         if (estate->es_into_relation_descriptor != NULL)
1198         {
1199                 heap_insert(estate->es_into_relation_descriptor, tuple,
1200                                         estate->es_snapshot->curcid);
1201                 IncrAppended();
1202         }
1203
1204         /*
1205          * send the tuple to the front end (or the screen)
1206          */
1207         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1208         IncrRetrieved();
1209         (estate->es_processed)++;
1210 }
1211
1212 /* ----------------------------------------------------------------
1213  *              ExecInsert
1214  *
1215  *              INSERTs are trickier.. we have to insert the tuple into
1216  *              the base relation and insert appropriate tuples into the
1217  *              index relations.
1218  * ----------------------------------------------------------------
1219  */
1220 static void
1221 ExecInsert(TupleTableSlot *slot,
1222                    ItemPointer tupleid,
1223                    EState *estate)
1224 {
1225         HeapTuple       tuple;
1226         ResultRelInfo *resultRelInfo;
1227         Relation        resultRelationDesc;
1228         int                     numIndices;
1229         Oid                     newId;
1230
1231         /*
1232          * get the heap tuple out of the tuple table slot
1233          */
1234         tuple = slot->val;
1235
1236         /*
1237          * get information on the (current) result relation
1238          */
1239         resultRelInfo = estate->es_result_relation_info;
1240         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1241
1242         /* BEFORE ROW INSERT Triggers */
1243         if (resultRelInfo->ri_TrigDesc &&
1244                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1245         {
1246                 HeapTuple       newtuple;
1247
1248                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1249
1250                 if (newtuple == NULL)   /* "do nothing" */
1251                         return;
1252
1253                 if (newtuple != tuple)  /* modified by Trigger(s) */
1254                 {
1255                         /*
1256                          * Insert modified tuple into tuple table slot, replacing the
1257                          * original.  We assume that it was allocated in per-tuple
1258                          * memory context, and therefore will go away by itself. The
1259                          * tuple table slot should not try to clear it.
1260                          */
1261                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1262                         tuple = newtuple;
1263                 }
1264         }
1265
1266         /*
1267          * Check the constraints of the tuple
1268          */
1269         if (resultRelationDesc->rd_att->constr)
1270                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1271
1272         /*
1273          * insert the tuple
1274          */
1275         newId = heap_insert(resultRelationDesc, tuple,
1276                                                 estate->es_snapshot->curcid);
1277
1278         IncrAppended();
1279         (estate->es_processed)++;
1280         estate->es_lastoid = newId;
1281         setLastTid(&(tuple->t_self));
1282
1283         /*
1284          * process indices
1285          *
1286          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1287          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1288          * field.
1289          */
1290         numIndices = resultRelInfo->ri_NumIndices;
1291         if (numIndices > 0)
1292                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1293
1294         /* AFTER ROW INSERT Triggers */
1295         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1296 }
1297
1298 /* ----------------------------------------------------------------
1299  *              ExecDelete
1300  *
1301  *              DELETE is like UPDATE, we delete the tuple and its
1302  *              index tuples.
1303  * ----------------------------------------------------------------
1304  */
1305 static void
1306 ExecDelete(TupleTableSlot *slot,
1307                    ItemPointer tupleid,
1308                    EState *estate)
1309 {
1310         ResultRelInfo *resultRelInfo;
1311         Relation        resultRelationDesc;
1312         ItemPointerData ctid;
1313         int                     result;
1314
1315         /*
1316          * get information on the (current) result relation
1317          */
1318         resultRelInfo = estate->es_result_relation_info;
1319         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1320
1321         /* BEFORE ROW DELETE Triggers */
1322         if (resultRelInfo->ri_TrigDesc &&
1323           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1324         {
1325                 bool            dodelete;
1326
1327                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1328
1329                 if (!dodelete)                  /* "do nothing" */
1330                         return;
1331         }
1332
1333         /*
1334          * delete the tuple
1335          */
1336 ldelete:;
1337         result = heap_delete(resultRelationDesc, tupleid,
1338                                                  &ctid,
1339                                                  estate->es_snapshot->curcid);
1340         switch (result)
1341         {
1342                 case HeapTupleSelfUpdated:
1343                         /* already deleted by self; nothing to do */
1344                         return;
1345
1346                 case HeapTupleMayBeUpdated:
1347                         break;
1348
1349                 case HeapTupleUpdated:
1350                         if (XactIsoLevel == XACT_SERIALIZABLE)
1351                                 elog(ERROR, "Can't serialize access due to concurrent update");
1352                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1353                         {
1354                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1355                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1356
1357                                 if (!TupIsNull(epqslot))
1358                                 {
1359                                         *tupleid = ctid;
1360                                         goto ldelete;
1361                                 }
1362                         }
1363                         /* tuple already deleted; nothing to do */
1364                         return;
1365
1366                 default:
1367                         elog(ERROR, "Unknown status %u from heap_delete", result);
1368                         return;
1369         }
1370
1371         IncrDeleted();
1372         (estate->es_processed)++;
1373
1374         /*
1375          * Note: Normally one would think that we have to delete index tuples
1376          * associated with the heap tuple now..
1377          *
1378          * ... but in POSTGRES, we have no need to do this because the vacuum
1379          * daemon automatically opens an index scan and deletes index tuples
1380          * when it finds deleted heap tuples. -cim 9/27/89
1381          */
1382
1383         /* AFTER ROW DELETE Triggers */
1384         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1385 }
1386
1387 /* ----------------------------------------------------------------
1388  *              ExecUpdate
1389  *
1390  *              note: we can't run UPDATE queries with transactions
1391  *              off because UPDATEs are actually INSERTs and our
1392  *              scan will mistakenly loop forever, updating the tuple
1393  *              it just inserted..      This should be fixed but until it
1394  *              is, we don't want to get stuck in an infinite loop
1395  *              which corrupts your database..
1396  * ----------------------------------------------------------------
1397  */
1398 static void
1399 ExecUpdate(TupleTableSlot *slot,
1400                    ItemPointer tupleid,
1401                    EState *estate)
1402 {
1403         HeapTuple       tuple;
1404         ResultRelInfo *resultRelInfo;
1405         Relation        resultRelationDesc;
1406         ItemPointerData ctid;
1407         int                     result;
1408         int                     numIndices;
1409
1410         /*
1411          * abort the operation if not running transactions
1412          */
1413         if (IsBootstrapProcessingMode())
1414         {
1415                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1416                 return;
1417         }
1418
1419         /*
1420          * get the heap tuple out of the tuple table slot
1421          */
1422         tuple = slot->val;
1423
1424         /*
1425          * get information on the (current) result relation
1426          */
1427         resultRelInfo = estate->es_result_relation_info;
1428         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1429
1430         /* BEFORE ROW UPDATE Triggers */
1431         if (resultRelInfo->ri_TrigDesc &&
1432           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1433         {
1434                 HeapTuple       newtuple;
1435
1436                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1437                                                                                 tupleid, tuple);
1438
1439                 if (newtuple == NULL)   /* "do nothing" */
1440                         return;
1441
1442                 if (newtuple != tuple)  /* modified by Trigger(s) */
1443                 {
1444                         /*
1445                          * Insert modified tuple into tuple table slot, replacing the
1446                          * original.  We assume that it was allocated in per-tuple
1447                          * memory context, and therefore will go away by itself. The
1448                          * tuple table slot should not try to clear it.
1449                          */
1450                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1451                         tuple = newtuple;
1452                 }
1453         }
1454
1455         /*
1456          * Check the constraints of the tuple
1457          *
1458          * If we generate a new candidate tuple after EvalPlanQual testing, we
1459          * must loop back here and recheck constraints.  (We don't need to
1460          * redo triggers, however.      If there are any BEFORE triggers then
1461          * trigger.c will have done mark4update to lock the correct tuple, so
1462          * there's no need to do them again.)
1463          */
1464 lreplace:;
1465         if (resultRelationDesc->rd_att->constr)
1466                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1467
1468         /*
1469          * replace the heap tuple
1470          */
1471         result = heap_update(resultRelationDesc, tupleid, tuple,
1472                                                  &ctid,
1473                                                  estate->es_snapshot->curcid);
1474         switch (result)
1475         {
1476                 case HeapTupleSelfUpdated:
1477                         /* already deleted by self; nothing to do */
1478                         return;
1479
1480                 case HeapTupleMayBeUpdated:
1481                         break;
1482
1483                 case HeapTupleUpdated:
1484                         if (XactIsoLevel == XACT_SERIALIZABLE)
1485                                 elog(ERROR, "Can't serialize access due to concurrent update");
1486                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1487                         {
1488                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1489                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1490
1491                                 if (!TupIsNull(epqslot))
1492                                 {
1493                                         *tupleid = ctid;
1494                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1495                                         slot = ExecStoreTuple(tuple,
1496                                                                         estate->es_junkFilter->jf_resultSlot,
1497                                                                                   InvalidBuffer, true);
1498                                         goto lreplace;
1499                                 }
1500                         }
1501                         /* tuple already deleted; nothing to do */
1502                         return;
1503
1504                 default:
1505                         elog(ERROR, "Unknown status %u from heap_update", result);
1506                         return;
1507         }
1508
1509         IncrReplaced();
1510         (estate->es_processed)++;
1511
1512         /*
1513          * Note: instead of having to update the old index tuples associated
1514          * with the heap tuple, all we do is form and insert new index tuples.
1515          * This is because UPDATEs are actually DELETEs and INSERTs and index
1516          * tuple deletion is done automagically by the vacuum daemon. All we
1517          * do is insert new index tuples.  -cim 9/27/89
1518          */
1519
1520         /*
1521          * process indices
1522          *
1523          * heap_update updates a tuple in the base relation by invalidating it
1524          * and then inserting a new tuple to the relation.      As a side effect,
1525          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1526          * field.  So we now insert index tuples using the new tupleid stored
1527          * there.
1528          */
1529
1530         numIndices = resultRelInfo->ri_NumIndices;
1531         if (numIndices > 0)
1532                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1533
1534         /* AFTER ROW UPDATE Triggers */
1535         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1536 }
1537
1538 static char *
1539 ExecRelCheck(ResultRelInfo *resultRelInfo,
1540                          TupleTableSlot *slot, EState *estate)
1541 {
1542         Relation        rel = resultRelInfo->ri_RelationDesc;
1543         int                     ncheck = rel->rd_att->constr->num_check;
1544         ConstrCheck *check = rel->rd_att->constr->check;
1545         ExprContext *econtext;
1546         MemoryContext oldContext;
1547         List       *qual;
1548         int                     i;
1549
1550         /*
1551          * If first time through for this result relation, build expression
1552          * nodetrees for rel's constraint expressions.  Keep them in the
1553          * per-query memory context so they'll survive throughout the query.
1554          */
1555         if (resultRelInfo->ri_ConstraintExprs == NULL)
1556         {
1557                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1558                 resultRelInfo->ri_ConstraintExprs =
1559                         (List **) palloc(ncheck * sizeof(List *));
1560                 for (i = 0; i < ncheck; i++)
1561                 {
1562                         qual = (List *) stringToNode(check[i].ccbin);
1563                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1564                 }
1565                 MemoryContextSwitchTo(oldContext);
1566         }
1567
1568         /*
1569          * We will use the EState's per-tuple context for evaluating
1570          * constraint expressions (creating it if it's not already there).
1571          */
1572         econtext = GetPerTupleExprContext(estate);
1573
1574         /* Arrange for econtext's scan tuple to be the tuple under test */
1575         econtext->ecxt_scantuple = slot;
1576
1577         /* And evaluate the constraints */
1578         for (i = 0; i < ncheck; i++)
1579         {
1580                 qual = resultRelInfo->ri_ConstraintExprs[i];
1581
1582                 /*
1583                  * NOTE: SQL92 specifies that a NULL result from a constraint
1584                  * expression is not to be treated as a failure.  Therefore, tell
1585                  * ExecQual to return TRUE for NULL.
1586                  */
1587                 if (!ExecQual(qual, econtext, true))
1588                         return check[i].ccname;
1589         }
1590
1591         /* NULL result means no error */
1592         return (char *) NULL;
1593 }
1594
1595 void
1596 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1597                                 TupleTableSlot *slot, EState *estate)
1598 {
1599         Relation        rel = resultRelInfo->ri_RelationDesc;
1600         HeapTuple       tuple = slot->val;
1601         TupleConstr *constr = rel->rd_att->constr;
1602
1603         Assert(constr);
1604
1605         if (constr->has_not_null)
1606         {
1607                 int                     natts = rel->rd_att->natts;
1608                 int                     attrChk;
1609
1610                 for (attrChk = 1; attrChk <= natts; attrChk++)
1611                 {
1612                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1613                                 heap_attisnull(tuple, attrChk))
1614                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1615                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1616                 }
1617         }
1618
1619         if (constr->num_check > 0)
1620         {
1621                 char       *failed;
1622
1623                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1624                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1625                                  caller, failed, RelationGetRelationName(rel));
1626         }
1627 }
1628
1629 /*
1630  * Check a modified tuple to see if we want to process its updated version
1631  * under READ COMMITTED rules.
1632  *
1633  * See backend/executor/README for some info about how this works.
1634  */
1635 TupleTableSlot *
1636 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1637 {
1638         evalPlanQual *epq;
1639         EState     *epqstate;
1640         Relation        relation;
1641         HeapTupleData tuple;
1642         HeapTuple       copyTuple = NULL;
1643         int                     rtsize;
1644         bool            endNode;
1645
1646         Assert(rti != 0);
1647
1648         /*
1649          * find relation containing target tuple
1650          */
1651         if (estate->es_result_relation_info != NULL &&
1652                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1653                 relation = estate->es_result_relation_info->ri_RelationDesc;
1654         else
1655         {
1656                 List       *l;
1657
1658                 relation = NULL;
1659                 foreach(l, estate->es_rowMark)
1660                 {
1661                         if (((execRowMark *) lfirst(l))->rti == rti)
1662                         {
1663                                 relation = ((execRowMark *) lfirst(l))->relation;
1664                                 break;
1665                         }
1666                 }
1667                 if (relation == NULL)
1668                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1669         }
1670
1671         /*
1672          * fetch tid tuple
1673          *
1674          * Loop here to deal with updated or busy tuples
1675          */
1676         tuple.t_self = *tid;
1677         for (;;)
1678         {
1679                 Buffer          buffer;
1680
1681                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1682                 {
1683                         TransactionId xwait = SnapshotDirty->xmax;
1684
1685                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1686                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1687
1688                         /*
1689                          * If tuple is being updated by other transaction then we have
1690                          * to wait for its commit/abort.
1691                          */
1692                         if (TransactionIdIsValid(xwait))
1693                         {
1694                                 ReleaseBuffer(buffer);
1695                                 XactLockTableWait(xwait);
1696                                 continue;
1697                         }
1698
1699                         /*
1700                          * We got tuple - now copy it for use by recheck query.
1701                          */
1702                         copyTuple = heap_copytuple(&tuple);
1703                         ReleaseBuffer(buffer);
1704                         break;
1705                 }
1706
1707                 /*
1708                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1709                  * Note that it's possible to get invalid SnapshotDirty->tid if
1710                  * tuple updated by this transaction. Have we to check this ?
1711                  */
1712                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1713                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1714                 {
1715                         /* updated, so look at the updated copy */
1716                         tuple.t_self = SnapshotDirty->tid;
1717                         continue;
1718                 }
1719
1720                 /*
1721                  * Deleted or updated by this transaction; forget it.
1722                  */
1723                 return NULL;
1724         }
1725
1726         /*
1727          * For UPDATE/DELETE we have to return tid of actual row we're
1728          * executing PQ for.
1729          */
1730         *tid = tuple.t_self;
1731
1732         /*
1733          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1734          */
1735         epq = (evalPlanQual *) estate->es_evalPlanQual;
1736         rtsize = length(estate->es_range_table);
1737         endNode = true;
1738
1739         if (epq != NULL && epq->rti == 0)
1740         {
1741                 /* Top PQ stack entry is idle, so re-use it */
1742                 Assert(!(estate->es_useEvalPlan) &&
1743                            epq->estate.es_evalPlanQual == NULL);
1744                 epq->rti = rti;
1745                 endNode = false;
1746         }
1747
1748         /*
1749          * If this is request for another RTE - Ra, - then we have to check
1750          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1751          * updated again and we have to re-start old execution for Ra and
1752          * forget all what we done after Ra was suspended. Cool? -:))
1753          */
1754         if (epq != NULL && epq->rti != rti &&
1755                 epq->estate.es_evTuple[rti - 1] != NULL)
1756         {
1757                 do
1758                 {
1759                         evalPlanQual *oldepq;
1760
1761                         /* pop previous PlanQual from the stack */
1762                         epqstate = &(epq->estate);
1763                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1764                         Assert(oldepq->rti != 0);
1765                         /* stop execution */
1766                         ExecEndNode(epq->plan, NULL);
1767                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1768                         epqstate->es_tupleTable = NULL;
1769                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1770                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1771                         /* push current PQ to freePQ stack */
1772                         oldepq->free = epq;
1773                         epq = oldepq;
1774                         estate->es_evalPlanQual = (Pointer) epq;
1775                 } while (epq->rti != rti);
1776         }
1777
1778         /*
1779          * If we are requested for another RTE then we have to suspend
1780          * execution of current PlanQual and start execution for new one.
1781          */
1782         if (epq == NULL || epq->rti != rti)
1783         {
1784                 /* try to reuse plan used previously */
1785                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1786
1787                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1788                 {
1789                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1790                         newepq->free = NULL;
1791
1792                         /*
1793                          * Each stack level has its own copy of the plan tree.  This
1794                          * is wasteful, but necessary as long as plan nodes point to
1795                          * exec state nodes rather than vice versa.  Note that
1796                          * copyfuncs.c doesn't attempt to copy the exec state nodes,
1797                          * which is a good thing in this situation.
1798                          */
1799                         newepq->plan = copyObject(estate->es_origPlan);
1800
1801                         /*
1802                          * Init stack level's EState.  We share top level's copy of
1803                          * es_result_relations array and other non-changing status. We
1804                          * need our own tupletable, es_param_exec_vals, and other
1805                          * changeable state.
1806                          */
1807                         epqstate = &(newepq->estate);
1808                         memcpy(epqstate, estate, sizeof(EState));
1809                         epqstate->es_direction = ForwardScanDirection;
1810                         if (estate->es_origPlan->nParamExec > 0)
1811                                 epqstate->es_param_exec_vals = (ParamExecData *)
1812                                         palloc(estate->es_origPlan->nParamExec *
1813                                                    sizeof(ParamExecData));
1814                         epqstate->es_tupleTable = NULL;
1815                         epqstate->es_per_tuple_exprcontext = NULL;
1816
1817                         /*
1818                          * Each epqstate must have its own es_evTupleNull state, but
1819                          * all the stack entries share es_evTuple state.  This allows
1820                          * sub-rechecks to inherit the value being examined by an
1821                          * outer recheck.
1822                          */
1823                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1824                         if (epq == NULL)
1825                                 /* first PQ stack entry */
1826                                 epqstate->es_evTuple = (HeapTuple *)
1827                                         palloc0(rtsize * sizeof(HeapTuple));
1828                         else
1829                                 /* later stack entries share the same storage */
1830                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1831                 }
1832                 else
1833                 {
1834                         /* recycle previously used EState */
1835                         epqstate = &(newepq->estate);
1836                 }
1837                 /* push current PQ to the stack */
1838                 epqstate->es_evalPlanQual = (Pointer) epq;
1839                 epq = newepq;
1840                 estate->es_evalPlanQual = (Pointer) epq;
1841                 epq->rti = rti;
1842                 endNode = false;
1843         }
1844
1845         Assert(epq->rti == rti);
1846         epqstate = &(epq->estate);
1847
1848         /*
1849          * Ok - we're requested for the same RTE.  Unfortunately we still have
1850          * to end and restart execution of the plan, because ExecReScan
1851          * wouldn't ensure that upper plan nodes would reset themselves.  We
1852          * could make that work if insertion of the target tuple were
1853          * integrated with the Param mechanism somehow, so that the upper plan
1854          * nodes know that their children's outputs have changed.
1855          */
1856         if (endNode)
1857         {
1858                 /* stop execution */
1859                 ExecEndNode(epq->plan, NULL);
1860                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1861                 epqstate->es_tupleTable = NULL;
1862         }
1863
1864         /*
1865          * free old RTE' tuple, if any, and store target tuple where
1866          * relation's scan node will see it
1867          */
1868         if (epqstate->es_evTuple[rti - 1] != NULL)
1869                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1870         epqstate->es_evTuple[rti - 1] = copyTuple;
1871
1872         /*
1873          * Initialize for new recheck query; be careful to copy down state
1874          * that might have changed in top EState.
1875          */
1876         epqstate->es_result_relation_info = estate->es_result_relation_info;
1877         epqstate->es_junkFilter = estate->es_junkFilter;
1878         if (estate->es_origPlan->nParamExec > 0)
1879                 memset(epqstate->es_param_exec_vals, 0,
1880                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1881         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1882         epqstate->es_useEvalPlan = false;
1883         Assert(epqstate->es_tupleTable == NULL);
1884         epqstate->es_tupleTable =
1885                 ExecCreateTupleTable(estate->es_tupleTable->size);
1886
1887         ExecInitNode(epq->plan, epqstate, NULL);
1888
1889         return EvalPlanQualNext(estate);
1890 }
1891
1892 static TupleTableSlot *
1893 EvalPlanQualNext(EState *estate)
1894 {
1895         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1896         EState     *epqstate = &(epq->estate);
1897         evalPlanQual *oldepq;
1898         TupleTableSlot *slot;
1899
1900         Assert(epq->rti != 0);
1901
1902 lpqnext:;
1903         slot = ExecProcNode(epq->plan, NULL);
1904
1905         /*
1906          * No more tuples for this PQ. Continue previous one.
1907          */
1908         if (TupIsNull(slot))
1909         {
1910                 /* stop execution */
1911                 ExecEndNode(epq->plan, NULL);
1912                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1913                 epqstate->es_tupleTable = NULL;
1914                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1915                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1916                 /* pop old PQ from the stack */
1917                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1918                 if (oldepq == (evalPlanQual *) NULL)
1919                 {
1920                         epq->rti = 0;           /* this is the first (oldest) */
1921                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1922                         return (NULL);          /* continue Query execution   */
1923                 }
1924                 Assert(oldepq->rti != 0);
1925                 /* push current PQ to freePQ stack */
1926                 oldepq->free = epq;
1927                 epq = oldepq;
1928                 epqstate = &(epq->estate);
1929                 estate->es_evalPlanQual = (Pointer) epq;
1930                 goto lpqnext;
1931         }
1932
1933         return (slot);
1934 }
1935
1936 static void
1937 EndEvalPlanQual(EState *estate)
1938 {
1939         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1940         EState     *epqstate = &(epq->estate);
1941         evalPlanQual *oldepq;
1942
1943         if (epq->rti == 0)                      /* plans already shutdowned */
1944         {
1945                 Assert(epq->estate.es_evalPlanQual == NULL);
1946                 return;
1947         }
1948
1949         for (;;)
1950         {
1951                 /* stop execution */
1952                 ExecEndNode(epq->plan, NULL);
1953                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1954                 epqstate->es_tupleTable = NULL;
1955                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1956                 {
1957                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1958                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1959                 }
1960                 /* pop old PQ from the stack */
1961                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1962                 if (oldepq == (evalPlanQual *) NULL)
1963                 {
1964                         epq->rti = 0;           /* this is the first (oldest) */
1965                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1966                         break;
1967                 }
1968                 Assert(oldepq->rti != 0);
1969                 /* push current PQ to freePQ stack */
1970                 oldepq->free = epq;
1971                 epq = oldepq;
1972                 epqstate = &(epq->estate);
1973                 estate->es_evalPlanQual = (Pointer) epq;
1974         }
1975 }