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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 is required as an argument.
  16  *
  17  *      ExecutorStart() must be called at the beginning of execution of any
  18  *      query plan and ExecutorEnd() should always be called at the end of
  19  *      execution of a plan.
  20  *
  21  *      ExecutorRun accepts direction and count arguments that specify whether
  22  *      the plan is to be executed forwards, backwards, and for how many tuples.
  23  *
  24  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  25  * Portions Copyright (c) 1994, Regents of the University of California
  26  *
  27  *
  28  * IDENTIFICATION
  29  *        $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.198 2003/01/12 18:19:37 petere Exp $
  30  *
  31  *-------------------------------------------------------------------------
  32  */
  33 #include "postgres.h"
  34
  35 #include "access/heapam.h"
  36 #include "catalog/heap.h"
  37 #include "catalog/namespace.h"
  38 #include "commands/tablecmds.h"
  39 #include "commands/trigger.h"
  40 #include "executor/execdebug.h"
  41 #include "executor/execdefs.h"
  42 #include "miscadmin.h"
  43 #include "optimizer/var.h"
  44 #include "parser/parsetree.h"
  45 #include "utils/acl.h"
  46 #include "utils/lsyscache.h"
  47
  48
  49 typedef struct execRowMark
  50 {
  51         Relation        relation;
  52         Index           rti;
  53         char            resname[32];
  54 } execRowMark;
  55
  56 typedef struct evalPlanQual
  57 {
  58         Index           rti;
  59         EState     *estate;
  60         PlanState  *planstate;
  61         struct evalPlanQual *next;      /* stack of active PlanQual plans */
  62         struct evalPlanQual *free;      /* list of free PlanQual plans */
  63 } evalPlanQual;
  64
  65 /* decls for local routines only used within this module */
  66 static void InitPlan(QueryDesc *queryDesc);
  67 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  68                                   Index resultRelationIndex,
  69                                   List *rangeTable,
  70                                   CmdType operation);
  71 static TupleTableSlot *ExecutePlan(EState *estate, PlanState *planstate,
  72                         CmdType operation,
  73                         long numberTuples,
  74                         ScanDirection direction,
  75                         DestReceiver *destfunc);
  76 static void ExecSelect(TupleTableSlot *slot,
  77                    DestReceiver *destfunc,
  78                    EState *estate);
  79 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  80                    EState *estate);
  81 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  82                    EState *estate);
  83 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  84                    EState *estate);
  85 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  86 static void EndEvalPlanQual(EState *estate);
  87 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  88 static void ExecCheckXactReadOnly(Query *parsetree, CmdType operation);
  89 static void EvalPlanQualStart(evalPlanQual *epq, EState *estate,
  90                                                           evalPlanQual *priorepq);
  91 static void EvalPlanQualStop(evalPlanQual *epq);
  92
  93 /* end of local decls */
  94
  95
  96 /* ----------------------------------------------------------------
  97  *              ExecutorStart
  98  *
  99  *              This routine must be called at the beginning of any execution of any
 100  *              query plan
 101  *
 102  * Takes a QueryDesc previously created by CreateQueryDesc (it's not real
 103  * clear why we bother to separate the two functions, but...).  The tupDesc
 104  * field of the QueryDesc is filled in to describe the tuples that will be
 105  * returned, and the internal fields (estate and planstate) are set up.
 106  *
 107  * NB: the CurrentMemoryContext when this is called will become the parent
 108  * of the per-query context used for this Executor invocation.
 109  * ----------------------------------------------------------------
 110  */
 111 void
 112 ExecutorStart(QueryDesc *queryDesc)
 113 {
 114         EState     *estate;
 115         MemoryContext oldcontext;
 116
 117         /* sanity checks: queryDesc must not be started already */
 118         Assert(queryDesc != NULL);
 119         Assert(queryDesc->estate == NULL);
 120
 121         /*
 122          * Build EState, switch into per-query memory context for startup.
 123          */
 124         estate = CreateExecutorState();
 125         queryDesc->estate = estate;
 126
 127         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 128
 129         /*
 130          * Fill in parameters, if any, from queryDesc
 131          */
 132         estate->es_param_list_info = queryDesc->params;
 133
 134         if (queryDesc->plantree->nParamExec > 0)
 135                 estate->es_param_exec_vals = (ParamExecData *)
 136                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 137
 138         estate->es_instrument = queryDesc->doInstrument;
 139
 140         /*
 141          * Make our own private copy of the current query snapshot data.
 142          *
 143          * This "freezes" our idea of which tuples are good and which are not for
 144          * the life of this query, even if it outlives the current command and
 145          * current snapshot.
 146          */
 147         estate->es_snapshot = CopyQuerySnapshot();
 148
 149         /*
 150          * Initialize the plan state tree
 151          */
 152         InitPlan(queryDesc);
 153
 154         MemoryContextSwitchTo(oldcontext);
 155 }
 156
 157 /* ----------------------------------------------------------------
 158  *              ExecutorRun
 159  *
 160  *              This is the main routine of the executor module. It accepts
 161  *              the query descriptor from the traffic cop and executes the
 162  *              query plan.
 163  *
 164  *              ExecutorStart must have been called already.
 165  *
 166  *              If direction is NoMovementScanDirection then nothing is done
 167  *              except to start up/shut down the destination.  Otherwise,
 168  *              we retrieve up to 'count' tuples in the specified direction.
 169  *
 170  *              Note: count = 0 is interpreted as no portal limit, i.e., run to
 171  *              completion.
 172  *
 173  * ----------------------------------------------------------------
 174  */
 175 TupleTableSlot *
 176 ExecutorRun(QueryDesc *queryDesc,
 177                         ScanDirection direction, long count)
 178 {
 179         EState     *estate;
 180         CmdType         operation;
 181         CommandDest dest;
 182         DestReceiver *destfunc;
 183         TupleTableSlot *result;
 184         MemoryContext oldcontext;
 185
 186         /* sanity checks */
 187         Assert(queryDesc != NULL);
 188
 189         estate = queryDesc->estate;
 190
 191         Assert(estate != NULL);
 192
 193         /*
 194          * Switch into per-query memory context
 195          */
 196         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 197
 198         /*
 199          * extract information from the query descriptor and the query
 200          * feature.
 201          */
 202         operation = queryDesc->operation;
 203         dest = queryDesc->dest;
 204
 205         /*
 206          * If the transaction is read-only, we need to check if any writes
 207          * are planned to non-temporary tables.  This is done here at this
 208          * rather late stage so that we can handle EXPLAIN vs. EXPLAIN
 209          * ANALYZE easily.
 210          */
 211         ExecCheckXactReadOnly(queryDesc->parsetree, operation);
 212
 213         /*
 214          * startup tuple receiver
 215          */
 216         estate->es_processed = 0;
 217         estate->es_lastoid = InvalidOid;
 218
 219         destfunc = DestToFunction(dest);
 220         (*destfunc->setup) (destfunc, (int) operation,
 221                                                 queryDesc->portalName, queryDesc->tupDesc);
 222
 223         /*
 224          * run plan
 225          */
 226         if (direction == NoMovementScanDirection)
 227                 result = NULL;
 228         else
 229                 result = ExecutePlan(estate,
 230                                                          queryDesc->planstate,
 231                                                          operation,
 232                                                          count,
 233                                                          direction,
 234                                                          destfunc);
 235
 236         /*
 237          * shutdown receiver
 238          */
 239         (*destfunc->cleanup) (destfunc);
 240
 241         MemoryContextSwitchTo(oldcontext);
 242
 243         return result;
 244 }
 245
 246 /* ----------------------------------------------------------------
 247  *              ExecutorEnd
 248  *
 249  *              This routine must be called at the end of execution of any
 250  *              query plan
 251  * ----------------------------------------------------------------
 252  */
 253 void
 254 ExecutorEnd(QueryDesc *queryDesc)
 255 {
 256         EState     *estate;
 257         MemoryContext oldcontext;
 258
 259         /* sanity checks */
 260         Assert(queryDesc != NULL);
 261
 262         estate = queryDesc->estate;
 263
 264         Assert(estate != NULL);
 265
 266         /*
 267          * Switch into per-query memory context to run ExecEndPlan
 268          */
 269         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 270
 271         ExecEndPlan(queryDesc->planstate, estate);
 272
 273         /*
 274          * Must switch out of context before destroying it
 275          */
 276         MemoryContextSwitchTo(oldcontext);
 277
 278         /*
 279          * Release EState and per-query memory context.  This should release
 280          * everything the executor has allocated.
 281          */
 282         FreeExecutorState(estate);
 283
 284         /* Reset queryDesc fields that no longer point to anything */
 285         queryDesc->tupDesc = NULL;
 286         queryDesc->estate = NULL;
 287         queryDesc->planstate = NULL;
 288 }
 289
 290
 291 /*
 292  * ExecCheckRTPerms
 293  *              Check access permissions for all relations listed in a range table.
 294  */
 295 void
 296 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 297 {
 298         List       *lp;
 299
 300         foreach(lp, rangeTable)
 301         {
 302                 RangeTblEntry *rte = lfirst(lp);
 303
 304                 ExecCheckRTEPerms(rte, operation);
 305         }
 306 }
 307
 308 /*
 309  * ExecCheckRTEPerms
 310  *              Check access permissions for a single RTE.
 311  */
 312 static void
 313 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 314 {
 315         Oid                     relOid;
 316         AclId           userid;
 317         AclResult       aclcheck_result;
 318
 319         /*
 320          * If it's a subquery, recursively examine its rangetable.
 321          */
 322         if (rte->rtekind == RTE_SUBQUERY)
 323         {
 324                 ExecCheckRTPerms(rte->subquery->rtable, operation);
 325                 return;
 326         }
 327
 328         /*
 329          * Otherwise, only plain-relation RTEs need to be checked here.
 330          * Function RTEs are checked by init_fcache when the function is prepared
 331          * for execution. Join and special RTEs need no checks.
 332          */
 333         if (rte->rtekind != RTE_RELATION)
 334                 return;
 335
 336         relOid = rte->relid;
 337
 338         /*
 339          * userid to check as: current user unless we have a setuid
 340          * indication.
 341          *
 342          * Note: GetUserId() is presently fast enough that there's no harm in
 343          * calling it separately for each RTE.  If that stops being true, we
 344          * could call it once in ExecCheckRTPerms and pass the userid down
 345          * from there.  But for now, no need for the extra clutter.
 346          */
 347         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 348
 349 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 350
 351         if (rte->checkForRead)
 352         {
 353                 aclcheck_result = CHECK(ACL_SELECT);
 354                 if (aclcheck_result != ACLCHECK_OK)
 355                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 356         }
 357
 358         if (rte->checkForWrite)
 359         {
 360                 /*
 361                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 362                  * Right now we don't distinguish that from true update as far as
 363                  * permissions checks are concerned.
 364                  */
 365                 switch (operation)
 366                 {
 367                         case CMD_INSERT:
 368                                 aclcheck_result = CHECK(ACL_INSERT);
 369                                 break;
 370                         case CMD_SELECT:
 371                         case CMD_UPDATE:
 372                                 aclcheck_result = CHECK(ACL_UPDATE);
 373                                 break;
 374                         case CMD_DELETE:
 375                                 aclcheck_result = CHECK(ACL_DELETE);
 376                                 break;
 377                         default:
 378                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 379                                          operation);
 380                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 381                                 break;
 382                 }
 383                 if (aclcheck_result != ACLCHECK_OK)
 384                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 385         }
 386 }
 387
 388
 389 /* ===============================================================
 390  * ===============================================================
 391                                                  static routines follow
 392  * ===============================================================
 393  * ===============================================================
 394  */
 395
 396
 397 static void
 398 ExecCheckXactReadOnly(Query *parsetree, CmdType operation)
 399 {
 400         if (!XactReadOnly)
 401                 return;
 402
 403         /* CREATE TABLE AS or SELECT INTO */
 404         if (operation == CMD_SELECT && parsetree->into != NULL)
 405                 goto fail;
 406
 407         if (operation == CMD_DELETE || operation == CMD_INSERT
 408                 || operation == CMD_UPDATE)
 409         {
 410                 List *lp;
 411
 412                 foreach(lp, parsetree->rtable)
 413                 {
 414                         RangeTblEntry *rte = lfirst(lp);
 415
 416                         if (rte->rtekind != RTE_RELATION)
 417                                 continue;
 418
 419                         if (!rte->checkForWrite)
 420                                 continue;
 421
 422                         if (isTempNamespace(get_rel_namespace(rte->relid)))
 423                                 continue;
 424
 425                         goto fail;
 426                 }
 427         }
 428
 429         return;
 430
 431 fail:
 432         elog(ERROR, "transaction is read-only");
 433 }
 434
 435
 436 /* ----------------------------------------------------------------
 437  *              InitPlan
 438  *
 439  *              Initializes the query plan: open files, allocate storage
 440  *              and start up the rule manager
 441  * ----------------------------------------------------------------
 442  */
 443 static void
 444 InitPlan(QueryDesc *queryDesc)
 445 {
 446         CmdType         operation = queryDesc->operation;
 447         Query *parseTree = queryDesc->parsetree;
 448         Plan *plan = queryDesc->plantree;
 449         EState *estate = queryDesc->estate;
 450         PlanState  *planstate;
 451         List       *rangeTable;
 452         Relation        intoRelationDesc;
 453         TupleDesc       tupType;
 454
 455         /*
 456          * Do permissions checks.  It's sufficient to examine the query's
 457          * top rangetable here --- subplan RTEs will be checked during
 458          * ExecInitSubPlan().
 459          */
 460         ExecCheckRTPerms(parseTree->rtable, operation);
 461
 462         /*
 463          * get information from query descriptor
 464          */
 465         rangeTable = parseTree->rtable;
 466
 467         /*
 468          * initialize the node's execution state
 469          */
 470         estate->es_range_table = rangeTable;
 471
 472         /*
 473          * if there is a result relation, initialize result relation stuff
 474          */
 475         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 476         {
 477                 List       *resultRelations = parseTree->resultRelations;
 478                 int                     numResultRelations;
 479                 ResultRelInfo *resultRelInfos;
 480
 481                 if (resultRelations != NIL)
 482                 {
 483                         /*
 484                          * Multiple result relations (due to inheritance)
 485                          * parseTree->resultRelations identifies them all
 486                          */
 487                         ResultRelInfo *resultRelInfo;
 488
 489                         numResultRelations = length(resultRelations);
 490                         resultRelInfos = (ResultRelInfo *)
 491                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 492                         resultRelInfo = resultRelInfos;
 493                         while (resultRelations != NIL)
 494                         {
 495                                 initResultRelInfo(resultRelInfo,
 496                                                                   lfirsti(resultRelations),
 497                                                                   rangeTable,
 498                                                                   operation);
 499                                 resultRelInfo++;
 500                                 resultRelations = lnext(resultRelations);
 501                         }
 502                 }
 503                 else
 504                 {
 505                         /*
 506                          * Single result relation identified by
 507                          * parseTree->resultRelation
 508                          */
 509                         numResultRelations = 1;
 510                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 511                         initResultRelInfo(resultRelInfos,
 512                                                           parseTree->resultRelation,
 513                                                           rangeTable,
 514                                                           operation);
 515                 }
 516
 517                 estate->es_result_relations = resultRelInfos;
 518                 estate->es_num_result_relations = numResultRelations;
 519                 /* Initialize to first or only result rel */
 520                 estate->es_result_relation_info = resultRelInfos;
 521         }
 522         else
 523         {
 524                 /*
 525                  * if no result relation, then set state appropriately
 526                  */
 527                 estate->es_result_relations = NULL;
 528                 estate->es_num_result_relations = 0;
 529                 estate->es_result_relation_info = NULL;
 530         }
 531
 532         /*
 533          * Have to lock relations selected for update
 534          */
 535         estate->es_rowMark = NIL;
 536         if (parseTree->rowMarks != NIL)
 537         {
 538                 List       *l;
 539
 540                 foreach(l, parseTree->rowMarks)
 541                 {
 542                         Index           rti = lfirsti(l);
 543                         Oid                     relid = getrelid(rti, rangeTable);
 544                         Relation        relation;
 545                         execRowMark *erm;
 546
 547                         relation = heap_open(relid, RowShareLock);
 548                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 549                         erm->relation = relation;
 550                         erm->rti = rti;
 551                         snprintf(erm->resname, 32, "ctid%u", rti);
 552                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 553                 }
 554         }
 555
 556         /*
 557          * initialize the executor "tuple" table.  We need slots for all the
 558          * plan nodes, plus possibly output slots for the junkfilter(s). At
 559          * this point we aren't sure if we need junkfilters, so just add slots
 560          * for them unconditionally.
 561          */
 562         {
 563                 int                     nSlots = ExecCountSlotsNode(plan);
 564
 565                 if (parseTree->resultRelations != NIL)
 566                         nSlots += length(parseTree->resultRelations);
 567                 else
 568                         nSlots += 1;
 569                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 570         }
 571
 572         /* mark EvalPlanQual not active */
 573         estate->es_topPlan = plan;
 574         estate->es_evalPlanQual = NULL;
 575         estate->es_evTupleNull = NULL;
 576         estate->es_evTuple = NULL;
 577         estate->es_useEvalPlan = false;
 578
 579         /*
 580          * initialize the private state information for all the nodes in the
 581          * query tree.  This opens files, allocates storage and leaves us
 582          * ready to start processing tuples.
 583          */
 584         planstate = ExecInitNode(plan, estate);
 585
 586         /*
 587          * Get the tuple descriptor describing the type of tuples to return.
 588          * (this is especially important if we are creating a relation with
 589          * "SELECT INTO")
 590          */
 591         tupType = ExecGetTupType(planstate);
 592
 593         /*
 594          * Initialize the junk filter if needed. SELECT and INSERT queries
 595          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 596          * DELETE always need one, since there's always a junk 'ctid'
 597          * attribute present --- no need to look first.
 598          */
 599         {
 600                 bool            junk_filter_needed = false;
 601                 List       *tlist;
 602
 603                 switch (operation)
 604                 {
 605                         case CMD_SELECT:
 606                         case CMD_INSERT:
 607                                 foreach(tlist, plan->targetlist)
 608                                 {
 609                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 610
 611                                         if (tle->resdom->resjunk)
 612                                         {
 613                                                 junk_filter_needed = true;
 614                                                 break;
 615                                         }
 616                                 }
 617                                 break;
 618                         case CMD_UPDATE:
 619                         case CMD_DELETE:
 620                                 junk_filter_needed = true;
 621                                 break;
 622                         default:
 623                                 break;
 624                 }
 625
 626                 if (junk_filter_needed)
 627                 {
 628                         /*
 629                          * If there are multiple result relations, each one needs its
 630                          * own junk filter.  Note this is only possible for
 631                          * UPDATE/DELETE, so we can't be fooled by some needing a
 632                          * filter and some not.
 633                          */
 634                         if (parseTree->resultRelations != NIL)
 635                         {
 636                                 PlanState **appendplans;
 637                                 int                     as_nplans;
 638                                 ResultRelInfo *resultRelInfo;
 639                                 int                     i;
 640
 641                                 /* Top plan had better be an Append here. */
 642                                 Assert(IsA(plan, Append));
 643                                 Assert(((Append *) plan)->isTarget);
 644                                 Assert(IsA(planstate, AppendState));
 645                                 appendplans = ((AppendState *) planstate)->appendplans;
 646                                 as_nplans = ((AppendState *) planstate)->as_nplans;
 647                                 Assert(as_nplans == estate->es_num_result_relations);
 648                                 resultRelInfo = estate->es_result_relations;
 649                                 for (i = 0; i < as_nplans; i++)
 650                                 {
 651                                         PlanState  *subplan = appendplans[i];
 652                                         JunkFilter *j;
 653
 654                                         j = ExecInitJunkFilter(subplan->plan->targetlist,
 655                                                                                    ExecGetTupType(subplan),
 656                                                           ExecAllocTableSlot(estate->es_tupleTable));
 657                                         resultRelInfo->ri_junkFilter = j;
 658                                         resultRelInfo++;
 659                                 }
 660
 661                                 /*
 662                                  * Set active junkfilter too; at this point ExecInitAppend
 663                                  * has already selected an active result relation...
 664                                  */
 665                                 estate->es_junkFilter =
 666                                         estate->es_result_relation_info->ri_junkFilter;
 667                         }
 668                         else
 669                         {
 670                                 /* Normal case with just one JunkFilter */
 671                                 JunkFilter *j;
 672
 673                                 j = ExecInitJunkFilter(planstate->plan->targetlist,
 674                                                                            tupType,
 675                                                           ExecAllocTableSlot(estate->es_tupleTable));
 676                                 estate->es_junkFilter = j;
 677                                 if (estate->es_result_relation_info)
 678                                         estate->es_result_relation_info->ri_junkFilter = j;
 679
 680                                 /* For SELECT, want to return the cleaned tuple type */
 681                                 if (operation == CMD_SELECT)
 682                                         tupType = j->jf_cleanTupType;
 683                         }
 684                 }
 685                 else
 686                         estate->es_junkFilter = NULL;
 687         }
 688
 689         /*
 690          * initialize the "into" relation
 691          */
 692         intoRelationDesc = (Relation) NULL;
 693
 694         if (operation == CMD_SELECT)
 695         {
 696                 if (!parseTree->isPortal)
 697                 {
 698                         /*
 699                          * a select into table --- need to create the "into" table
 700                          */
 701                         if (parseTree->into != NULL)
 702                         {
 703                                 char       *intoName;
 704                                 Oid                     namespaceId;
 705                                 AclResult       aclresult;
 706                                 Oid                     intoRelationId;
 707                                 TupleDesc       tupdesc;
 708
 709                                 /*
 710                                  * find namespace to create in, check permissions
 711                                  */
 712                                 intoName = parseTree->into->relname;
 713                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 714
 715                                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 716                                                                                                   ACL_CREATE);
 717                                 if (aclresult != ACLCHECK_OK)
 718                                         aclcheck_error(aclresult,
 719                                                                    get_namespace_name(namespaceId));
 720
 721                                 /*
 722                                  * have to copy tupType to get rid of constraints
 723                                  */
 724                                 tupdesc = CreateTupleDescCopy(tupType);
 725
 726                                 /*
 727                                  * Formerly we forced the output table to have OIDs, but
 728                                  * as of 7.3 it will not have OIDs, because it's too late
 729                                  * here to change the tupdescs of the already-initialized
 730                                  * plan tree.  (Perhaps we could recurse and change them
 731                                  * all, but it's not really worth the trouble IMHO...)
 732                                  */
 733
 734                                 intoRelationId =
 735                                         heap_create_with_catalog(intoName,
 736                                                                                          namespaceId,
 737                                                                                          tupdesc,
 738                                                                                          RELKIND_RELATION,
 739                                                                                          false,
 740                                                                                          ONCOMMIT_NOOP,
 741                                                                                          allowSystemTableMods);
 742
 743                                 FreeTupleDesc(tupdesc);
 744
 745                                 /*
 746                                  * Advance command counter so that the newly-created
 747                                  * relation's catalog tuples will be visible to heap_open.
 748                                  */
 749                                 CommandCounterIncrement();
 750
 751                                 /*
 752                                  * If necessary, create a TOAST table for the into
 753                                  * relation. Note that AlterTableCreateToastTable ends
 754                                  * with CommandCounterIncrement(), so that the TOAST table
 755                                  * will be visible for insertion.
 756                                  */
 757                                 AlterTableCreateToastTable(intoRelationId, true);
 758
 759                                 intoRelationDesc = heap_open(intoRelationId,
 760                                                                                          AccessExclusiveLock);
 761                         }
 762                 }
 763         }
 764
 765         estate->es_into_relation_descriptor = intoRelationDesc;
 766
 767         queryDesc->tupDesc = tupType;
 768         queryDesc->planstate = planstate;
 769 }
 770
 771 /*
 772  * Initialize ResultRelInfo data for one result relation
 773  */
 774 static void
 775 initResultRelInfo(ResultRelInfo *resultRelInfo,
 776                                   Index resultRelationIndex,
 777                                   List *rangeTable,
 778                                   CmdType operation)
 779 {
 780         Oid                     resultRelationOid;
 781         Relation        resultRelationDesc;
 782
 783         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 784         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 785
 786         switch (resultRelationDesc->rd_rel->relkind)
 787         {
 788                 case RELKIND_SEQUENCE:
 789                         elog(ERROR, "You can't change sequence relation %s",
 790                                  RelationGetRelationName(resultRelationDesc));
 791                         break;
 792                 case RELKIND_TOASTVALUE:
 793                         elog(ERROR, "You can't change toast relation %s",
 794                                  RelationGetRelationName(resultRelationDesc));
 795                         break;
 796                 case RELKIND_VIEW:
 797                         elog(ERROR, "You can't change view relation %s",
 798                                  RelationGetRelationName(resultRelationDesc));
 799                         break;
 800         }
 801
 802         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 803         resultRelInfo->type = T_ResultRelInfo;
 804         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 805         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 806         resultRelInfo->ri_NumIndices = 0;
 807         resultRelInfo->ri_IndexRelationDescs = NULL;
 808         resultRelInfo->ri_IndexRelationInfo = NULL;
 809         /* make a copy so as not to depend on relcache info not changing... */
 810         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 811         resultRelInfo->ri_TrigFunctions = NULL;
 812         resultRelInfo->ri_ConstraintExprs = NULL;
 813         resultRelInfo->ri_junkFilter = NULL;
 814
 815         /*
 816          * If there are indices on the result relation, open them and save
 817          * descriptors in the result relation info, so that we can add new
 818          * index entries for the tuples we add/update.  We need not do this
 819          * for a DELETE, however, since deletion doesn't affect indexes.
 820          */
 821         if (resultRelationDesc->rd_rel->relhasindex &&
 822                 operation != CMD_DELETE)
 823                 ExecOpenIndices(resultRelInfo);
 824 }
 825
 826 /* ----------------------------------------------------------------
 827  *              ExecEndPlan
 828  *
 829  *              Cleans up the query plan -- closes files and frees up storage
 830  *
 831  * NOTE: we are no longer very worried about freeing storage per se
 832  * in this code; FreeExecutorState should be guaranteed to release all
 833  * memory that needs to be released.  What we are worried about doing
 834  * is closing relations and dropping buffer pins.  Thus, for example,
 835  * tuple tables must be cleared or dropped to ensure pins are released.
 836  * ----------------------------------------------------------------
 837  */
 838 void
 839 ExecEndPlan(PlanState *planstate, EState *estate)
 840 {
 841         ResultRelInfo *resultRelInfo;
 842         int                     i;
 843         List       *l;
 844
 845         /*
 846          * shut down any PlanQual processing we were doing
 847          */
 848         if (estate->es_evalPlanQual != NULL)
 849                 EndEvalPlanQual(estate);
 850
 851         /*
 852          * shut down the node-type-specific query processing
 853          */
 854         ExecEndNode(planstate);
 855
 856         /*
 857          * destroy the executor "tuple" table.
 858          */
 859         ExecDropTupleTable(estate->es_tupleTable, true);
 860         estate->es_tupleTable = NULL;
 861
 862         /*
 863          * close the result relation(s) if any, but hold locks until xact
 864          * commit.
 865          */
 866         resultRelInfo = estate->es_result_relations;
 867         for (i = estate->es_num_result_relations; i > 0; i--)
 868         {
 869                 /* Close indices and then the relation itself */
 870                 ExecCloseIndices(resultRelInfo);
 871                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 872                 resultRelInfo++;
 873         }
 874
 875         /*
 876          * close the "into" relation if necessary, again keeping lock
 877          */
 878         if (estate->es_into_relation_descriptor != NULL)
 879                 heap_close(estate->es_into_relation_descriptor, NoLock);
 880
 881         /*
 882          * close any relations selected FOR UPDATE, again keeping locks
 883          */
 884         foreach(l, estate->es_rowMark)
 885         {
 886                 execRowMark *erm = lfirst(l);
 887
 888                 heap_close(erm->relation, NoLock);
 889         }
 890 }
 891
 892 /* ----------------------------------------------------------------
 893  *              ExecutePlan
 894  *
 895  *              processes the query plan to retrieve 'numberTuples' tuples in the
 896  *              direction specified.
 897  *
 898  *              Retrieves all tuples if numberTuples is 0
 899  *
 900  *              result is either a slot containing the last tuple in the case
 901  *              of a SELECT or NULL otherwise.
 902  *
 903  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 904  * user can see it
 905  * ----------------------------------------------------------------
 906  */
 907 static TupleTableSlot *
 908 ExecutePlan(EState *estate,
 909                         PlanState *planstate,
 910                         CmdType operation,
 911                         long numberTuples,
 912                         ScanDirection direction,
 913                         DestReceiver *destfunc)
 914 {
 915         JunkFilter                      *junkfilter;
 916         TupleTableSlot          *slot;
 917         ItemPointer                      tupleid = NULL;
 918         ItemPointerData          tuple_ctid;
 919         long                             current_tuple_count;
 920         TupleTableSlot          *result;
 921
 922         /*
 923          * initialize local variables
 924          */
 925         slot = NULL;
 926         current_tuple_count = 0;
 927         result = NULL;
 928
 929         /*
 930          * Set the direction.
 931          */
 932         estate->es_direction = direction;
 933
 934         /*
 935          * Process BEFORE EACH STATEMENT triggers
 936          */
 937         switch (operation)
 938         {
 939                 case CMD_UPDATE:
 940                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 941                         break;
 942                 case CMD_DELETE:
 943                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 944                         break;
 945                 case CMD_INSERT:
 946                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 947                         break;
 948                 default:
 949                         /* do nothing */
 950                         break;
 951         }
 952
 953         /*
 954          * Loop until we've processed the proper number of tuples from the
 955          * plan.
 956          */
 957
 958         for (;;)
 959         {
 960                 /* Reset the per-output-tuple exprcontext */
 961                 ResetPerTupleExprContext(estate);
 962
 963                 /*
 964                  * Execute the plan and obtain a tuple
 965                  */
 966 lnext:  ;
 967                 if (estate->es_useEvalPlan)
 968                 {
 969                         slot = EvalPlanQualNext(estate);
 970                         if (TupIsNull(slot))
 971                                 slot = ExecProcNode(planstate);
 972                 }
 973                 else
 974                         slot = ExecProcNode(planstate);
 975
 976                 /*
 977                  * if the tuple is null, then we assume there is nothing more to
 978                  * process so we just return null...
 979                  */
 980                 if (TupIsNull(slot))
 981                 {
 982                         result = NULL;
 983                         break;
 984                 }
 985
 986                 /*
 987                  * if we have a junk filter, then project a new tuple with the
 988                  * junk removed.
 989                  *
 990                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 991                  * (Formerly, we stored it back over the "dirty" tuple, which is
 992                  * WRONG because that tuple slot has the wrong descriptor.)
 993                  *
 994                  * Also, extract all the junk information we need.
 995                  */
 996                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 997                 {
 998                         Datum           datum;
 999                         HeapTuple       newTuple;
1000                         bool            isNull;
1001
1002                         /*
1003                          * extract the 'ctid' junk attribute.
1004                          */
1005                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1006                         {
1007                                 if (!ExecGetJunkAttribute(junkfilter,
1008                                                                                   slot,
1009                                                                                   "ctid",
1010                                                                                   &datum,
1011                                                                                   &isNull))
1012                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1013
1014                                 /* shouldn't ever get a null result... */
1015                                 if (isNull)
1016                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1017
1018                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1019                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1020                                                                                  * ctid!! */
1021                                 tupleid = &tuple_ctid;
1022                         }
1023                         else if (estate->es_rowMark != NIL)
1024                         {
1025                                 List       *l;
1026
1027                 lmark:  ;
1028                                 foreach(l, estate->es_rowMark)
1029                                 {
1030                                         execRowMark *erm = lfirst(l);
1031                                         Buffer          buffer;
1032                                         HeapTupleData tuple;
1033                                         TupleTableSlot *newSlot;
1034                                         int                     test;
1035
1036                                         if (!ExecGetJunkAttribute(junkfilter,
1037                                                                                           slot,
1038                                                                                           erm->resname,
1039                                                                                           &datum,
1040                                                                                           &isNull))
1041                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1042                                                          erm->resname);
1043
1044                                         /* shouldn't ever get a null result... */
1045                                         if (isNull)
1046                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1047                                                          erm->resname);
1048
1049                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1050                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1051                                                                                         estate->es_snapshot->curcid);
1052                                         ReleaseBuffer(buffer);
1053                                         switch (test)
1054                                         {
1055                                                 case HeapTupleSelfUpdated:
1056                                                         /* treat it as deleted; do not process */
1057                                                         goto lnext;
1058
1059                                                 case HeapTupleMayBeUpdated:
1060                                                         break;
1061
1062                                                 case HeapTupleUpdated:
1063                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1064                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1065                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1066                                                                   (ItemPointer) DatumGetPointer(datum))))
1067                                                         {
1068                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1069                                                                 if (!(TupIsNull(newSlot)))
1070                                                                 {
1071                                                                         slot = newSlot;
1072                                                                         estate->es_useEvalPlan = true;
1073                                                                         goto lmark;
1074                                                                 }
1075                                                         }
1076
1077                                                         /*
1078                                                          * if tuple was deleted or PlanQual failed for
1079                                                          * updated tuple - we must not return this
1080                                                          * tuple!
1081                                                          */
1082                                                         goto lnext;
1083
1084                                                 default:
1085                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1086                                                         return (NULL);
1087                                         }
1088                                 }
1089                         }
1090
1091                         /*
1092                          * Finally create a new "clean" tuple with all junk attributes
1093                          * removed
1094                          */
1095                         newTuple = ExecRemoveJunk(junkfilter, slot);
1096
1097                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1098                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1099                                                                   InvalidBuffer,                /* this tuple has no
1100                                                                                                                  * buffer */
1101                                                                   true);                /* tuple should be pfreed */
1102                 }
1103
1104                 /*
1105                  * now that we have a tuple, do the appropriate thing with it..
1106                  * either return it to the user, add it to a relation someplace,
1107                  * delete it from a relation, or modify some of its attributes.
1108                  */
1109                 switch (operation)
1110                 {
1111                         case CMD_SELECT:
1112                                 ExecSelect(slot,        /* slot containing tuple */
1113                                                    destfunc,    /* destination's tuple-receiver
1114                                                                                  * obj */
1115                                                    estate);
1116                                 result = slot;
1117                                 break;
1118
1119                         case CMD_INSERT:
1120                                 ExecInsert(slot, tupleid, estate);
1121                                 result = NULL;
1122                                 break;
1123
1124                         case CMD_DELETE:
1125                                 ExecDelete(slot, tupleid, estate);
1126                                 result = NULL;
1127                                 break;
1128
1129                         case CMD_UPDATE:
1130                                 ExecUpdate(slot, tupleid, estate);
1131                                 result = NULL;
1132                                 break;
1133
1134                         default:
1135                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1136                                 result = NULL;
1137                                 break;
1138                 }
1139
1140                 /*
1141                  * check our tuple count.. if we've processed the proper number
1142                  * then quit, else loop again and process more tuples.  Zero
1143                  * numberTuples means no limit.
1144                  */
1145                 current_tuple_count++;
1146                 if (numberTuples && numberTuples == current_tuple_count)
1147                         break;
1148         }
1149
1150         /*
1151          * Process AFTER EACH STATEMENT triggers
1152          */
1153         switch (operation)
1154         {
1155                 case CMD_UPDATE:
1156                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1157                         break;
1158                 case CMD_DELETE:
1159                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1160                         break;
1161                 case CMD_INSERT:
1162                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1163                         break;
1164                 default:
1165                         /* do nothing */
1166                         break;
1167         }
1168
1169         /*
1170          * here, result is either a slot containing a tuple in the case of a
1171          * SELECT or NULL otherwise.
1172          */
1173         return result;
1174 }
1175
1176 /* ----------------------------------------------------------------
1177  *              ExecSelect
1178  *
1179  *              SELECTs are easy.. we just pass the tuple to the appropriate
1180  *              print function.  The only complexity is when we do a
1181  *              "SELECT INTO", in which case we insert the tuple into
1182  *              the appropriate relation (note: this is a newly created relation
1183  *              so we don't need to worry about indices or locks.)
1184  * ----------------------------------------------------------------
1185  */
1186 static void
1187 ExecSelect(TupleTableSlot *slot,
1188                    DestReceiver *destfunc,
1189                    EState *estate)
1190 {
1191         HeapTuple       tuple;
1192         TupleDesc       attrtype;
1193
1194         /*
1195          * get the heap tuple out of the tuple table slot
1196          */
1197         tuple = slot->val;
1198         attrtype = slot->ttc_tupleDescriptor;
1199
1200         /*
1201          * insert the tuple into the "into relation"
1202          */
1203         if (estate->es_into_relation_descriptor != NULL)
1204         {
1205                 heap_insert(estate->es_into_relation_descriptor, tuple,
1206                                         estate->es_snapshot->curcid);
1207                 IncrAppended();
1208         }
1209
1210         /*
1211          * send the tuple to the front end (or the screen)
1212          */
1213         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1214         IncrRetrieved();
1215         (estate->es_processed)++;
1216 }
1217
1218 /* ----------------------------------------------------------------
1219  *              ExecInsert
1220  *
1221  *              INSERTs are trickier.. we have to insert the tuple into
1222  *              the base relation and insert appropriate tuples into the
1223  *              index relations.
1224  * ----------------------------------------------------------------
1225  */
1226 static void
1227 ExecInsert(TupleTableSlot *slot,
1228                    ItemPointer tupleid,
1229                    EState *estate)
1230 {
1231         HeapTuple       tuple;
1232         ResultRelInfo *resultRelInfo;
1233         Relation        resultRelationDesc;
1234         int                     numIndices;
1235         Oid                     newId;
1236
1237         /*
1238          * get the heap tuple out of the tuple table slot
1239          */
1240         tuple = slot->val;
1241
1242         /*
1243          * get information on the (current) result relation
1244          */
1245         resultRelInfo = estate->es_result_relation_info;
1246         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1247
1248         /* BEFORE ROW INSERT Triggers */
1249         if (resultRelInfo->ri_TrigDesc &&
1250                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1251         {
1252                 HeapTuple       newtuple;
1253
1254                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1255
1256                 if (newtuple == NULL)   /* "do nothing" */
1257                         return;
1258
1259                 if (newtuple != tuple)  /* modified by Trigger(s) */
1260                 {
1261                         /*
1262                          * Insert modified tuple into tuple table slot, replacing the
1263                          * original.  We assume that it was allocated in per-tuple
1264                          * memory context, and therefore will go away by itself. The
1265                          * tuple table slot should not try to clear it.
1266                          */
1267                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1268                         tuple = newtuple;
1269                 }
1270         }
1271
1272         /*
1273          * Check the constraints of the tuple
1274          */
1275         if (resultRelationDesc->rd_att->constr)
1276                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1277
1278         /*
1279          * insert the tuple
1280          */
1281         newId = heap_insert(resultRelationDesc, tuple,
1282                                                 estate->es_snapshot->curcid);
1283
1284         IncrAppended();
1285         (estate->es_processed)++;
1286         estate->es_lastoid = newId;
1287         setLastTid(&(tuple->t_self));
1288
1289         /*
1290          * process indices
1291          *
1292          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1293          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1294          * field.
1295          */
1296         numIndices = resultRelInfo->ri_NumIndices;
1297         if (numIndices > 0)
1298                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1299
1300         /* AFTER ROW INSERT Triggers */
1301         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1302 }
1303
1304 /* ----------------------------------------------------------------
1305  *              ExecDelete
1306  *
1307  *              DELETE is like UPDATE, we delete the tuple and its
1308  *              index tuples.
1309  * ----------------------------------------------------------------
1310  */
1311 static void
1312 ExecDelete(TupleTableSlot *slot,
1313                    ItemPointer tupleid,
1314                    EState *estate)
1315 {
1316         ResultRelInfo *resultRelInfo;
1317         Relation        resultRelationDesc;
1318         ItemPointerData ctid;
1319         int                     result;
1320
1321         /*
1322          * get information on the (current) result relation
1323          */
1324         resultRelInfo = estate->es_result_relation_info;
1325         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1326
1327         /* BEFORE ROW DELETE Triggers */
1328         if (resultRelInfo->ri_TrigDesc &&
1329           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1330         {
1331                 bool            dodelete;
1332
1333                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1334
1335                 if (!dodelete)                  /* "do nothing" */
1336                         return;
1337         }
1338
1339         /*
1340          * delete the tuple
1341          */
1342 ldelete:;
1343         result = heap_delete(resultRelationDesc, tupleid,
1344                                                  &ctid,
1345                                                  estate->es_snapshot->curcid);
1346         switch (result)
1347         {
1348                 case HeapTupleSelfUpdated:
1349                         /* already deleted by self; nothing to do */
1350                         return;
1351
1352                 case HeapTupleMayBeUpdated:
1353                         break;
1354
1355                 case HeapTupleUpdated:
1356                         if (XactIsoLevel == XACT_SERIALIZABLE)
1357                                 elog(ERROR, "Can't serialize access due to concurrent update");
1358                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1359                         {
1360                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1361                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1362
1363                                 if (!TupIsNull(epqslot))
1364                                 {
1365                                         *tupleid = ctid;
1366                                         goto ldelete;
1367                                 }
1368                         }
1369                         /* tuple already deleted; nothing to do */
1370                         return;
1371
1372                 default:
1373                         elog(ERROR, "Unknown status %u from heap_delete", result);
1374                         return;
1375         }
1376
1377         IncrDeleted();
1378         (estate->es_processed)++;
1379
1380         /*
1381          * Note: Normally one would think that we have to delete index tuples
1382          * associated with the heap tuple now..
1383          *
1384          * ... but in POSTGRES, we have no need to do this because the vacuum
1385          * daemon automatically opens an index scan and deletes index tuples
1386          * when it finds deleted heap tuples. -cim 9/27/89
1387          */
1388
1389         /* AFTER ROW DELETE Triggers */
1390         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1391 }
1392
1393 /* ----------------------------------------------------------------
1394  *              ExecUpdate
1395  *
1396  *              note: we can't run UPDATE queries with transactions
1397  *              off because UPDATEs are actually INSERTs and our
1398  *              scan will mistakenly loop forever, updating the tuple
1399  *              it just inserted..      This should be fixed but until it
1400  *              is, we don't want to get stuck in an infinite loop
1401  *              which corrupts your database..
1402  * ----------------------------------------------------------------
1403  */
1404 static void
1405 ExecUpdate(TupleTableSlot *slot,
1406                    ItemPointer tupleid,
1407                    EState *estate)
1408 {
1409         HeapTuple       tuple;
1410         ResultRelInfo *resultRelInfo;
1411         Relation        resultRelationDesc;
1412         ItemPointerData ctid;
1413         int                     result;
1414         int                     numIndices;
1415
1416         /*
1417          * abort the operation if not running transactions
1418          */
1419         if (IsBootstrapProcessingMode())
1420         {
1421                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1422                 return;
1423         }
1424
1425         /*
1426          * get the heap tuple out of the tuple table slot
1427          */
1428         tuple = slot->val;
1429
1430         /*
1431          * get information on the (current) result relation
1432          */
1433         resultRelInfo = estate->es_result_relation_info;
1434         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1435
1436         /* BEFORE ROW UPDATE Triggers */
1437         if (resultRelInfo->ri_TrigDesc &&
1438           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1439         {
1440                 HeapTuple       newtuple;
1441
1442                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1443                                                                                 tupleid, tuple);
1444
1445                 if (newtuple == NULL)   /* "do nothing" */
1446                         return;
1447
1448                 if (newtuple != tuple)  /* modified by Trigger(s) */
1449                 {
1450                         /*
1451                          * Insert modified tuple into tuple table slot, replacing the
1452                          * original.  We assume that it was allocated in per-tuple
1453                          * memory context, and therefore will go away by itself. The
1454                          * tuple table slot should not try to clear it.
1455                          */
1456                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1457                         tuple = newtuple;
1458                 }
1459         }
1460
1461         /*
1462          * Check the constraints of the tuple
1463          *
1464          * If we generate a new candidate tuple after EvalPlanQual testing, we
1465          * must loop back here and recheck constraints.  (We don't need to
1466          * redo triggers, however.      If there are any BEFORE triggers then
1467          * trigger.c will have done mark4update to lock the correct tuple, so
1468          * there's no need to do them again.)
1469          */
1470 lreplace:;
1471         if (resultRelationDesc->rd_att->constr)
1472                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1473
1474         /*
1475          * replace the heap tuple
1476          */
1477         result = heap_update(resultRelationDesc, tupleid, tuple,
1478                                                  &ctid,
1479                                                  estate->es_snapshot->curcid);
1480         switch (result)
1481         {
1482                 case HeapTupleSelfUpdated:
1483                         /* already deleted by self; nothing to do */
1484                         return;
1485
1486                 case HeapTupleMayBeUpdated:
1487                         break;
1488
1489                 case HeapTupleUpdated:
1490                         if (XactIsoLevel == XACT_SERIALIZABLE)
1491                                 elog(ERROR, "Can't serialize access due to concurrent update");
1492                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1493                         {
1494                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1495                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1496
1497                                 if (!TupIsNull(epqslot))
1498                                 {
1499                                         *tupleid = ctid;
1500                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1501                                         slot = ExecStoreTuple(tuple,
1502                                                                         estate->es_junkFilter->jf_resultSlot,
1503                                                                                   InvalidBuffer, true);
1504                                         goto lreplace;
1505                                 }
1506                         }
1507                         /* tuple already deleted; nothing to do */
1508                         return;
1509
1510                 default:
1511                         elog(ERROR, "Unknown status %u from heap_update", result);
1512                         return;
1513         }
1514
1515         IncrReplaced();
1516         (estate->es_processed)++;
1517
1518         /*
1519          * Note: instead of having to update the old index tuples associated
1520          * with the heap tuple, all we do is form and insert new index tuples.
1521          * This is because UPDATEs are actually DELETEs and INSERTs and index
1522          * tuple deletion is done automagically by the vacuum daemon. All we
1523          * do is insert new index tuples.  -cim 9/27/89
1524          */
1525
1526         /*
1527          * process indices
1528          *
1529          * heap_update updates a tuple in the base relation by invalidating it
1530          * and then inserting a new tuple to the relation.      As a side effect,
1531          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1532          * field.  So we now insert index tuples using the new tupleid stored
1533          * there.
1534          */
1535
1536         numIndices = resultRelInfo->ri_NumIndices;
1537         if (numIndices > 0)
1538                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1539
1540         /* AFTER ROW UPDATE Triggers */
1541         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1542 }
1543
1544 static char *
1545 ExecRelCheck(ResultRelInfo *resultRelInfo,
1546                          TupleTableSlot *slot, EState *estate)
1547 {
1548         Relation        rel = resultRelInfo->ri_RelationDesc;
1549         int                     ncheck = rel->rd_att->constr->num_check;
1550         ConstrCheck *check = rel->rd_att->constr->check;
1551         ExprContext *econtext;
1552         MemoryContext oldContext;
1553         List       *qual;
1554         int                     i;
1555
1556         /*
1557          * If first time through for this result relation, build expression
1558          * nodetrees for rel's constraint expressions.  Keep them in the
1559          * per-query memory context so they'll survive throughout the query.
1560          */
1561         if (resultRelInfo->ri_ConstraintExprs == NULL)
1562         {
1563                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1564                 resultRelInfo->ri_ConstraintExprs =
1565                         (List **) palloc(ncheck * sizeof(List *));
1566                 for (i = 0; i < ncheck; i++)
1567                 {
1568                         qual = (List *) stringToNode(check[i].ccbin);
1569                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1570                                 ExecPrepareExpr((Expr *) qual, estate);
1571                 }
1572                 MemoryContextSwitchTo(oldContext);
1573         }
1574
1575         /*
1576          * We will use the EState's per-tuple context for evaluating
1577          * constraint expressions (creating it if it's not already there).
1578          */
1579         econtext = GetPerTupleExprContext(estate);
1580
1581         /* Arrange for econtext's scan tuple to be the tuple under test */
1582         econtext->ecxt_scantuple = slot;
1583
1584         /* And evaluate the constraints */
1585         for (i = 0; i < ncheck; i++)
1586         {
1587                 qual = resultRelInfo->ri_ConstraintExprs[i];
1588
1589                 /*
1590                  * NOTE: SQL92 specifies that a NULL result from a constraint
1591                  * expression is not to be treated as a failure.  Therefore, tell
1592                  * ExecQual to return TRUE for NULL.
1593                  */
1594                 if (!ExecQual(qual, econtext, true))
1595                         return check[i].ccname;
1596         }
1597
1598         /* NULL result means no error */
1599         return (char *) NULL;
1600 }
1601
1602 void
1603 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1604                                 TupleTableSlot *slot, EState *estate)
1605 {
1606         Relation        rel = resultRelInfo->ri_RelationDesc;
1607         HeapTuple       tuple = slot->val;
1608         TupleConstr *constr = rel->rd_att->constr;
1609
1610         Assert(constr);
1611
1612         if (constr->has_not_null)
1613         {
1614                 int                     natts = rel->rd_att->natts;
1615                 int                     attrChk;
1616
1617                 for (attrChk = 1; attrChk <= natts; attrChk++)
1618                 {
1619                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1620                                 heap_attisnull(tuple, attrChk))
1621                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1622                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1623                 }
1624         }
1625
1626         if (constr->num_check > 0)
1627         {
1628                 char       *failed;
1629
1630                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1631                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1632                                  caller, failed, RelationGetRelationName(rel));
1633         }
1634 }
1635
1636 /*
1637  * Check a modified tuple to see if we want to process its updated version
1638  * under READ COMMITTED rules.
1639  *
1640  * See backend/executor/README for some info about how this works.
1641  */
1642 TupleTableSlot *
1643 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1644 {
1645         evalPlanQual *epq;
1646         EState     *epqstate;
1647         Relation        relation;
1648         HeapTupleData tuple;
1649         HeapTuple       copyTuple = NULL;
1650         bool            endNode;
1651
1652         Assert(rti != 0);
1653
1654         /*
1655          * find relation containing target tuple
1656          */
1657         if (estate->es_result_relation_info != NULL &&
1658                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1659                 relation = estate->es_result_relation_info->ri_RelationDesc;
1660         else
1661         {
1662                 List       *l;
1663
1664                 relation = NULL;
1665                 foreach(l, estate->es_rowMark)
1666                 {
1667                         if (((execRowMark *) lfirst(l))->rti == rti)
1668                         {
1669                                 relation = ((execRowMark *) lfirst(l))->relation;
1670                                 break;
1671                         }
1672                 }
1673                 if (relation == NULL)
1674                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1675         }
1676
1677         /*
1678          * fetch tid tuple
1679          *
1680          * Loop here to deal with updated or busy tuples
1681          */
1682         tuple.t_self = *tid;
1683         for (;;)
1684         {
1685                 Buffer          buffer;
1686
1687                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1688                 {
1689                         TransactionId xwait = SnapshotDirty->xmax;
1690
1691                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1692                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1693
1694                         /*
1695                          * If tuple is being updated by other transaction then we have
1696                          * to wait for its commit/abort.
1697                          */
1698                         if (TransactionIdIsValid(xwait))
1699                         {
1700                                 ReleaseBuffer(buffer);
1701                                 XactLockTableWait(xwait);
1702                                 continue;
1703                         }
1704
1705                         /*
1706                          * We got tuple - now copy it for use by recheck query.
1707                          */
1708                         copyTuple = heap_copytuple(&tuple);
1709                         ReleaseBuffer(buffer);
1710                         break;
1711                 }
1712
1713                 /*
1714                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1715                  * Note that it's possible to get invalid SnapshotDirty->tid if
1716                  * tuple updated by this transaction. Have we to check this ?
1717                  */
1718                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1719                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1720                 {
1721                         /* updated, so look at the updated copy */
1722                         tuple.t_self = SnapshotDirty->tid;
1723                         continue;
1724                 }
1725
1726                 /*
1727                  * Deleted or updated by this transaction; forget it.
1728                  */
1729                 return NULL;
1730         }
1731
1732         /*
1733          * For UPDATE/DELETE we have to return tid of actual row we're
1734          * executing PQ for.
1735          */
1736         *tid = tuple.t_self;
1737
1738         /*
1739          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1740          */
1741         epq = estate->es_evalPlanQual;
1742         endNode = true;
1743
1744         if (epq != NULL && epq->rti == 0)
1745         {
1746                 /* Top PQ stack entry is idle, so re-use it */
1747                 Assert(!(estate->es_useEvalPlan) && epq->next == NULL);
1748                 epq->rti = rti;
1749                 endNode = false;
1750         }
1751
1752         /*
1753          * If this is request for another RTE - Ra, - then we have to check
1754          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1755          * updated again and we have to re-start old execution for Ra and
1756          * forget all what we done after Ra was suspended. Cool? -:))
1757          */
1758         if (epq != NULL && epq->rti != rti &&
1759                 epq->estate->es_evTuple[rti - 1] != NULL)
1760         {
1761                 do
1762                 {
1763                         evalPlanQual *oldepq;
1764
1765                         /* stop execution */
1766                         EvalPlanQualStop(epq);
1767                         /* pop previous PlanQual from the stack */
1768                         oldepq = epq->next;
1769                         Assert(oldepq && oldepq->rti != 0);
1770                         /* push current PQ to freePQ stack */
1771                         oldepq->free = epq;
1772                         epq = oldepq;
1773                         estate->es_evalPlanQual = epq;
1774                 } while (epq->rti != rti);
1775         }
1776
1777         /*
1778          * If we are requested for another RTE then we have to suspend
1779          * execution of current PlanQual and start execution for new one.
1780          */
1781         if (epq == NULL || epq->rti != rti)
1782         {
1783                 /* try to reuse plan used previously */
1784                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1785
1786                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1787                 {
1788                         newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual));
1789                         newepq->free = NULL;
1790                         newepq->estate = NULL;
1791                         newepq->planstate = NULL;
1792                 }
1793                 else
1794                 {
1795                         /* recycle previously used PlanQual */
1796                         Assert(newepq->estate == NULL);
1797                         epq->free = NULL;
1798                 }
1799                 /* push current PQ to the stack */
1800                 newepq->next = epq;
1801                 epq = newepq;
1802                 estate->es_evalPlanQual = epq;
1803                 epq->rti = rti;
1804                 endNode = false;
1805         }
1806
1807         Assert(epq->rti == rti);
1808
1809         /*
1810          * Ok - we're requested for the same RTE.  Unfortunately we still have
1811          * to end and restart execution of the plan, because ExecReScan
1812          * wouldn't ensure that upper plan nodes would reset themselves.  We
1813          * could make that work if insertion of the target tuple were
1814          * integrated with the Param mechanism somehow, so that the upper plan
1815          * nodes know that their children's outputs have changed.
1816          *
1817          * Note that the stack of free evalPlanQual nodes is quite useless at
1818          * the moment, since it only saves us from pallocing/releasing the
1819          * evalPlanQual nodes themselves.  But it will be useful once we
1820          * implement ReScan instead of end/restart for re-using PlanQual nodes.
1821          */
1822         if (endNode)
1823         {
1824                 /* stop execution */
1825                 EvalPlanQualStop(epq);
1826         }
1827
1828         /*
1829          * Initialize new recheck query.
1830          *
1831          * Note: if we were re-using PlanQual plans via ExecReScan, we'd need
1832          * to instead copy down changeable state from the top plan (including
1833          * es_result_relation_info, es_junkFilter) and reset locally changeable
1834          * state in the epq (including es_param_exec_vals, es_evTupleNull).
1835          */
1836         EvalPlanQualStart(epq, estate, epq->next);
1837
1838         /*
1839          * free old RTE' tuple, if any, and store target tuple where
1840          * relation's scan node will see it
1841          */
1842         epqstate = epq->estate;
1843         if (epqstate->es_evTuple[rti - 1] != NULL)
1844                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1845         epqstate->es_evTuple[rti - 1] = copyTuple;
1846
1847         return EvalPlanQualNext(estate);
1848 }
1849
1850 static TupleTableSlot *
1851 EvalPlanQualNext(EState *estate)
1852 {
1853         evalPlanQual *epq = estate->es_evalPlanQual;
1854         MemoryContext oldcontext;
1855         TupleTableSlot *slot;
1856
1857         Assert(epq->rti != 0);
1858
1859 lpqnext:;
1860         oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt);
1861         slot = ExecProcNode(epq->planstate);
1862         MemoryContextSwitchTo(oldcontext);
1863
1864         /*
1865          * No more tuples for this PQ. Continue previous one.
1866          */
1867         if (TupIsNull(slot))
1868         {
1869                 evalPlanQual *oldepq;
1870
1871                 /* stop execution */
1872                 EvalPlanQualStop(epq);
1873                 /* pop old PQ from the stack */
1874                 oldepq = epq->next;
1875                 if (oldepq == NULL)
1876                 {
1877                         /* this is the first (oldest) PQ - mark as free */
1878                         epq->rti = 0;
1879                         estate->es_useEvalPlan = false;
1880                         /* and continue Query execution */
1881                         return (NULL);
1882                 }
1883                 Assert(oldepq->rti != 0);
1884                 /* push current PQ to freePQ stack */
1885                 oldepq->free = epq;
1886                 epq = oldepq;
1887                 estate->es_evalPlanQual = epq;
1888                 goto lpqnext;
1889         }
1890
1891         return (slot);
1892 }
1893
1894 static void
1895 EndEvalPlanQual(EState *estate)
1896 {
1897         evalPlanQual *epq = estate->es_evalPlanQual;
1898
1899         if (epq->rti == 0)                      /* plans already shutdowned */
1900         {
1901                 Assert(epq->next == NULL);
1902                 return;
1903         }
1904
1905         for (;;)
1906         {
1907                 evalPlanQual *oldepq;
1908
1909                 /* stop execution */
1910                 EvalPlanQualStop(epq);
1911                 /* pop old PQ from the stack */
1912                 oldepq = epq->next;
1913                 if (oldepq == NULL)
1914                 {
1915                         /* this is the first (oldest) PQ - mark as free */
1916                         epq->rti = 0;
1917                         estate->es_useEvalPlan = false;
1918                         break;
1919                 }
1920                 Assert(oldepq->rti != 0);
1921                 /* push current PQ to freePQ stack */
1922                 oldepq->free = epq;
1923                 epq = oldepq;
1924                 estate->es_evalPlanQual = epq;
1925         }
1926 }
1927
1928 /*
1929  * Start execution of one level of PlanQual.
1930  *
1931  * This is a cut-down version of ExecutorStart(): we copy some state from
1932  * the top-level estate rather than initializing it fresh.
1933  */
1934 static void
1935 EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
1936 {
1937         EState     *epqstate;
1938         int                     rtsize;
1939         MemoryContext oldcontext;
1940
1941         rtsize = length(estate->es_range_table);
1942
1943         epq->estate = epqstate = CreateExecutorState();
1944
1945         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1946
1947         /*
1948          * The epqstates share the top query's copy of unchanging state such
1949          * as the snapshot, rangetable, result-rel info, and external Param info.
1950          * They need their own copies of local state, including a tuple table,
1951          * es_param_exec_vals, etc.
1952          */
1953         epqstate->es_direction = ForwardScanDirection;
1954         epqstate->es_snapshot = estate->es_snapshot;
1955         epqstate->es_range_table = estate->es_range_table;
1956         epqstate->es_result_relations = estate->es_result_relations;
1957         epqstate->es_num_result_relations = estate->es_num_result_relations;
1958         epqstate->es_result_relation_info = estate->es_result_relation_info;
1959         epqstate->es_junkFilter = estate->es_junkFilter;
1960         epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor;
1961         epqstate->es_param_list_info = estate->es_param_list_info;
1962         if (estate->es_topPlan->nParamExec > 0)
1963                 epqstate->es_param_exec_vals = (ParamExecData *)
1964                         palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
1965         epqstate->es_rowMark = estate->es_rowMark;
1966         epqstate->es_instrument = estate->es_instrument;
1967         epqstate->es_topPlan = estate->es_topPlan;
1968         /*
1969          * Each epqstate must have its own es_evTupleNull state, but
1970          * all the stack entries share es_evTuple state.  This allows
1971          * sub-rechecks to inherit the value being examined by an
1972          * outer recheck.
1973          */
1974         epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool));
1975         if (priorepq == NULL)
1976                 /* first PQ stack entry */
1977                 epqstate->es_evTuple = (HeapTuple *)
1978                         palloc0(rtsize * sizeof(HeapTuple));
1979         else
1980                 /* later stack entries share the same storage */
1981                 epqstate->es_evTuple = priorepq->estate->es_evTuple;
1982
1983         epqstate->es_tupleTable =
1984                 ExecCreateTupleTable(estate->es_tupleTable->size);
1985
1986         epq->planstate = ExecInitNode(estate->es_topPlan, epqstate);
1987
1988         MemoryContextSwitchTo(oldcontext);
1989 }
1990
1991 /*
1992  * End execution of one level of PlanQual.
1993  *
1994  * This is a cut-down version of ExecutorEnd(); basically we want to do most
1995  * of the normal cleanup, but *not* close result relations (which we are
1996  * just sharing from the outer query).
1997  */
1998 static void
1999 EvalPlanQualStop(evalPlanQual *epq)
2000 {
2001         EState     *epqstate = epq->estate;
2002         MemoryContext oldcontext;
2003
2004         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
2005
2006         ExecEndNode(epq->planstate);
2007
2008         ExecDropTupleTable(epqstate->es_tupleTable, true);
2009         epqstate->es_tupleTable = NULL;
2010
2011         if (epqstate->es_evTuple[epq->rti - 1] != NULL)
2012         {
2013                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
2014                 epqstate->es_evTuple[epq->rti - 1] = NULL;
2015         }
2016
2017         MemoryContextSwitchTo(oldcontext);
2018
2019         FreeExecutorState(epqstate);
2020
2021         epq->estate = NULL;
2022         epq->planstate = NULL;
2023 }