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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.196 2003/01/08 23:32:29 tgl 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 EvalPlanQualStart(evalPlanQual *epq, EState *estate,
  89                                                           evalPlanQual *priorepq);
  90 static void EvalPlanQualStop(evalPlanQual *epq);
  91
  92 /* end of local decls */
  93
  94
  95 /* ----------------------------------------------------------------
  96  *              ExecutorStart
  97  *
  98  *              This routine must be called at the beginning of any execution of any
  99  *              query plan
 100  *
 101  * Takes a QueryDesc previously created by CreateQueryDesc (it's not real
 102  * clear why we bother to separate the two functions, but...).  The tupDesc
 103  * field of the QueryDesc is filled in to describe the tuples that will be
 104  * returned, and the internal fields (estate and planstate) are set up.
 105  *
 106  * NB: the CurrentMemoryContext when this is called will become the parent
 107  * of the per-query context used for this Executor invocation.
 108  * ----------------------------------------------------------------
 109  */
 110 void
 111 ExecutorStart(QueryDesc *queryDesc)
 112 {
 113         EState     *estate;
 114         MemoryContext oldcontext;
 115
 116         /* sanity checks: queryDesc must not be started already */
 117         Assert(queryDesc != NULL);
 118         Assert(queryDesc->estate == NULL);
 119
 120         /*
 121          * Build EState, switch into per-query memory context for startup.
 122          */
 123         estate = CreateExecutorState();
 124         queryDesc->estate = estate;
 125
 126         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 127
 128         /*
 129          * Fill in parameters, if any, from queryDesc
 130          */
 131         estate->es_param_list_info = queryDesc->params;
 132
 133         if (queryDesc->plantree->nParamExec > 0)
 134                 estate->es_param_exec_vals = (ParamExecData *)
 135                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 136
 137         estate->es_instrument = queryDesc->doInstrument;
 138
 139         /*
 140          * Make our own private copy of the current query snapshot data.
 141          *
 142          * This "freezes" our idea of which tuples are good and which are not for
 143          * the life of this query, even if it outlives the current command and
 144          * current snapshot.
 145          */
 146         estate->es_snapshot = CopyQuerySnapshot();
 147
 148         /*
 149          * Initialize the plan state tree
 150          */
 151         InitPlan(queryDesc);
 152
 153         MemoryContextSwitchTo(oldcontext);
 154 }
 155
 156 /* ----------------------------------------------------------------
 157  *              ExecutorRun
 158  *
 159  *              This is the main routine of the executor module. It accepts
 160  *              the query descriptor from the traffic cop and executes the
 161  *              query plan.
 162  *
 163  *              ExecutorStart must have been called already.
 164  *
 165  *              If direction is NoMovementScanDirection then nothing is done
 166  *              except to start up/shut down the destination.  Otherwise,
 167  *              we retrieve up to 'count' tuples in the specified direction.
 168  *
 169  *              Note: count = 0 is interpreted as no portal limit, i.e., run to
 170  *              completion.
 171  *
 172  * ----------------------------------------------------------------
 173  */
 174 TupleTableSlot *
 175 ExecutorRun(QueryDesc *queryDesc,
 176                         ScanDirection direction, long count)
 177 {
 178         EState     *estate;
 179         CmdType         operation;
 180         CommandDest dest;
 181         DestReceiver *destfunc;
 182         TupleTableSlot *result;
 183         MemoryContext oldcontext;
 184
 185         /* sanity checks */
 186         Assert(queryDesc != NULL);
 187
 188         estate = queryDesc->estate;
 189
 190         Assert(estate != NULL);
 191
 192         /*
 193          * Switch into per-query memory context
 194          */
 195         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 196
 197         /*
 198          * extract information from the query descriptor and the query
 199          * feature.
 200          */
 201         operation = queryDesc->operation;
 202         dest = queryDesc->dest;
 203
 204         /*
 205          * startup tuple receiver
 206          */
 207         estate->es_processed = 0;
 208         estate->es_lastoid = InvalidOid;
 209
 210         destfunc = DestToFunction(dest);
 211         (*destfunc->setup) (destfunc, (int) operation,
 212                                                 queryDesc->portalName, queryDesc->tupDesc);
 213
 214         /*
 215          * run plan
 216          */
 217         if (direction == NoMovementScanDirection)
 218                 result = NULL;
 219         else
 220                 result = ExecutePlan(estate,
 221                                                          queryDesc->planstate,
 222                                                          operation,
 223                                                          count,
 224                                                          direction,
 225                                                          destfunc);
 226
 227         /*
 228          * shutdown receiver
 229          */
 230         (*destfunc->cleanup) (destfunc);
 231
 232         MemoryContextSwitchTo(oldcontext);
 233
 234         return result;
 235 }
 236
 237 /* ----------------------------------------------------------------
 238  *              ExecutorEnd
 239  *
 240  *              This routine must be called at the end of execution of any
 241  *              query plan
 242  * ----------------------------------------------------------------
 243  */
 244 void
 245 ExecutorEnd(QueryDesc *queryDesc)
 246 {
 247         EState     *estate;
 248         MemoryContext oldcontext;
 249
 250         /* sanity checks */
 251         Assert(queryDesc != NULL);
 252
 253         estate = queryDesc->estate;
 254
 255         Assert(estate != NULL);
 256
 257         /*
 258          * Switch into per-query memory context to run ExecEndPlan
 259          */
 260         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 261
 262         ExecEndPlan(queryDesc->planstate, estate);
 263
 264         /*
 265          * Must switch out of context before destroying it
 266          */
 267         MemoryContextSwitchTo(oldcontext);
 268
 269         /*
 270          * Release EState and per-query memory context.  This should release
 271          * everything the executor has allocated.
 272          */
 273         FreeExecutorState(estate);
 274
 275         /* Reset queryDesc fields that no longer point to anything */
 276         queryDesc->tupDesc = NULL;
 277         queryDesc->estate = NULL;
 278         queryDesc->planstate = NULL;
 279 }
 280
 281
 282 /*
 283  * ExecCheckRTPerms
 284  *              Check access permissions for all relations listed in a range table.
 285  */
 286 void
 287 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 288 {
 289         List       *lp;
 290
 291         foreach(lp, rangeTable)
 292         {
 293                 RangeTblEntry *rte = lfirst(lp);
 294
 295                 ExecCheckRTEPerms(rte, operation);
 296         }
 297 }
 298
 299 /*
 300  * ExecCheckRTEPerms
 301  *              Check access permissions for a single RTE.
 302  */
 303 static void
 304 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 305 {
 306         Oid                     relOid;
 307         AclId           userid;
 308         AclResult       aclcheck_result;
 309
 310         /*
 311          * If it's a subquery, recursively examine its rangetable.
 312          */
 313         if (rte->rtekind == RTE_SUBQUERY)
 314         {
 315                 ExecCheckRTPerms(rte->subquery->rtable, operation);
 316                 return;
 317         }
 318
 319         /*
 320          * Otherwise, only plain-relation RTEs need to be checked here.
 321          * Function RTEs are checked by init_fcache when the function is prepared
 322          * for execution. Join and special RTEs need no checks.
 323          */
 324         if (rte->rtekind != RTE_RELATION)
 325                 return;
 326
 327         relOid = rte->relid;
 328
 329         /*
 330          * userid to check as: current user unless we have a setuid
 331          * indication.
 332          *
 333          * Note: GetUserId() is presently fast enough that there's no harm in
 334          * calling it separately for each RTE.  If that stops being true, we
 335          * could call it once in ExecCheckRTPerms and pass the userid down
 336          * from there.  But for now, no need for the extra clutter.
 337          */
 338         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 339
 340 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 341
 342         if (rte->checkForRead)
 343         {
 344                 aclcheck_result = CHECK(ACL_SELECT);
 345                 if (aclcheck_result != ACLCHECK_OK)
 346                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 347         }
 348
 349         if (rte->checkForWrite)
 350         {
 351                 /*
 352                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 353                  * Right now we don't distinguish that from true update as far as
 354                  * permissions checks are concerned.
 355                  */
 356                 switch (operation)
 357                 {
 358                         case CMD_INSERT:
 359                                 aclcheck_result = CHECK(ACL_INSERT);
 360                                 break;
 361                         case CMD_SELECT:
 362                         case CMD_UPDATE:
 363                                 aclcheck_result = CHECK(ACL_UPDATE);
 364                                 break;
 365                         case CMD_DELETE:
 366                                 aclcheck_result = CHECK(ACL_DELETE);
 367                                 break;
 368                         default:
 369                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 370                                          operation);
 371                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 372                                 break;
 373                 }
 374                 if (aclcheck_result != ACLCHECK_OK)
 375                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 376         }
 377 }
 378
 379
 380 /* ===============================================================
 381  * ===============================================================
 382                                                  static routines follow
 383  * ===============================================================
 384  * ===============================================================
 385  */
 386
 387
 388 /* ----------------------------------------------------------------
 389  *              InitPlan
 390  *
 391  *              Initializes the query plan: open files, allocate storage
 392  *              and start up the rule manager
 393  * ----------------------------------------------------------------
 394  */
 395 static void
 396 InitPlan(QueryDesc *queryDesc)
 397 {
 398         CmdType         operation = queryDesc->operation;
 399         Query *parseTree = queryDesc->parsetree;
 400         Plan *plan = queryDesc->plantree;
 401         EState *estate = queryDesc->estate;
 402         PlanState  *planstate;
 403         List       *rangeTable;
 404         Relation        intoRelationDesc;
 405         TupleDesc       tupType;
 406
 407         /*
 408          * Do permissions checks.  It's sufficient to examine the query's
 409          * top rangetable here --- subplan RTEs will be checked during
 410          * ExecInitSubPlan().
 411          */
 412         ExecCheckRTPerms(parseTree->rtable, operation);
 413
 414         /*
 415          * get information from query descriptor
 416          */
 417         rangeTable = parseTree->rtable;
 418
 419         /*
 420          * initialize the node's execution state
 421          */
 422         estate->es_range_table = rangeTable;
 423
 424         /*
 425          * if there is a result relation, initialize result relation stuff
 426          */
 427         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 428         {
 429                 List       *resultRelations = parseTree->resultRelations;
 430                 int                     numResultRelations;
 431                 ResultRelInfo *resultRelInfos;
 432
 433                 if (resultRelations != NIL)
 434                 {
 435                         /*
 436                          * Multiple result relations (due to inheritance)
 437                          * parseTree->resultRelations identifies them all
 438                          */
 439                         ResultRelInfo *resultRelInfo;
 440
 441                         numResultRelations = length(resultRelations);
 442                         resultRelInfos = (ResultRelInfo *)
 443                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 444                         resultRelInfo = resultRelInfos;
 445                         while (resultRelations != NIL)
 446                         {
 447                                 initResultRelInfo(resultRelInfo,
 448                                                                   lfirsti(resultRelations),
 449                                                                   rangeTable,
 450                                                                   operation);
 451                                 resultRelInfo++;
 452                                 resultRelations = lnext(resultRelations);
 453                         }
 454                 }
 455                 else
 456                 {
 457                         /*
 458                          * Single result relation identified by
 459                          * parseTree->resultRelation
 460                          */
 461                         numResultRelations = 1;
 462                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 463                         initResultRelInfo(resultRelInfos,
 464                                                           parseTree->resultRelation,
 465                                                           rangeTable,
 466                                                           operation);
 467                 }
 468
 469                 estate->es_result_relations = resultRelInfos;
 470                 estate->es_num_result_relations = numResultRelations;
 471                 /* Initialize to first or only result rel */
 472                 estate->es_result_relation_info = resultRelInfos;
 473         }
 474         else
 475         {
 476                 /*
 477                  * if no result relation, then set state appropriately
 478                  */
 479                 estate->es_result_relations = NULL;
 480                 estate->es_num_result_relations = 0;
 481                 estate->es_result_relation_info = NULL;
 482         }
 483
 484         /*
 485          * Have to lock relations selected for update
 486          */
 487         estate->es_rowMark = NIL;
 488         if (parseTree->rowMarks != NIL)
 489         {
 490                 List       *l;
 491
 492                 foreach(l, parseTree->rowMarks)
 493                 {
 494                         Index           rti = lfirsti(l);
 495                         Oid                     relid = getrelid(rti, rangeTable);
 496                         Relation        relation;
 497                         execRowMark *erm;
 498
 499                         relation = heap_open(relid, RowShareLock);
 500                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 501                         erm->relation = relation;
 502                         erm->rti = rti;
 503                         snprintf(erm->resname, 32, "ctid%u", rti);
 504                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 505                 }
 506         }
 507
 508         /*
 509          * initialize the executor "tuple" table.  We need slots for all the
 510          * plan nodes, plus possibly output slots for the junkfilter(s). At
 511          * this point we aren't sure if we need junkfilters, so just add slots
 512          * for them unconditionally.
 513          */
 514         {
 515                 int                     nSlots = ExecCountSlotsNode(plan);
 516
 517                 if (parseTree->resultRelations != NIL)
 518                         nSlots += length(parseTree->resultRelations);
 519                 else
 520                         nSlots += 1;
 521                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 522         }
 523
 524         /* mark EvalPlanQual not active */
 525         estate->es_topPlan = plan;
 526         estate->es_evalPlanQual = NULL;
 527         estate->es_evTupleNull = NULL;
 528         estate->es_evTuple = NULL;
 529         estate->es_useEvalPlan = false;
 530
 531         /*
 532          * initialize the private state information for all the nodes in the
 533          * query tree.  This opens files, allocates storage and leaves us
 534          * ready to start processing tuples.
 535          */
 536         planstate = ExecInitNode(plan, estate);
 537
 538         /*
 539          * Get the tuple descriptor describing the type of tuples to return.
 540          * (this is especially important if we are creating a relation with
 541          * "SELECT INTO")
 542          */
 543         tupType = ExecGetTupType(planstate);
 544
 545         /*
 546          * Initialize the junk filter if needed. SELECT and INSERT queries
 547          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 548          * DELETE always need one, since there's always a junk 'ctid'
 549          * attribute present --- no need to look first.
 550          */
 551         {
 552                 bool            junk_filter_needed = false;
 553                 List       *tlist;
 554
 555                 switch (operation)
 556                 {
 557                         case CMD_SELECT:
 558                         case CMD_INSERT:
 559                                 foreach(tlist, plan->targetlist)
 560                                 {
 561                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 562
 563                                         if (tle->resdom->resjunk)
 564                                         {
 565                                                 junk_filter_needed = true;
 566                                                 break;
 567                                         }
 568                                 }
 569                                 break;
 570                         case CMD_UPDATE:
 571                         case CMD_DELETE:
 572                                 junk_filter_needed = true;
 573                                 break;
 574                         default:
 575                                 break;
 576                 }
 577
 578                 if (junk_filter_needed)
 579                 {
 580                         /*
 581                          * If there are multiple result relations, each one needs its
 582                          * own junk filter.  Note this is only possible for
 583                          * UPDATE/DELETE, so we can't be fooled by some needing a
 584                          * filter and some not.
 585                          */
 586                         if (parseTree->resultRelations != NIL)
 587                         {
 588                                 PlanState **appendplans;
 589                                 int                     as_nplans;
 590                                 ResultRelInfo *resultRelInfo;
 591                                 int                     i;
 592
 593                                 /* Top plan had better be an Append here. */
 594                                 Assert(IsA(plan, Append));
 595                                 Assert(((Append *) plan)->isTarget);
 596                                 Assert(IsA(planstate, AppendState));
 597                                 appendplans = ((AppendState *) planstate)->appendplans;
 598                                 as_nplans = ((AppendState *) planstate)->as_nplans;
 599                                 Assert(as_nplans == estate->es_num_result_relations);
 600                                 resultRelInfo = estate->es_result_relations;
 601                                 for (i = 0; i < as_nplans; i++)
 602                                 {
 603                                         PlanState  *subplan = appendplans[i];
 604                                         JunkFilter *j;
 605
 606                                         j = ExecInitJunkFilter(subplan->plan->targetlist,
 607                                                                                    ExecGetTupType(subplan),
 608                                                           ExecAllocTableSlot(estate->es_tupleTable));
 609                                         resultRelInfo->ri_junkFilter = j;
 610                                         resultRelInfo++;
 611                                 }
 612
 613                                 /*
 614                                  * Set active junkfilter too; at this point ExecInitAppend
 615                                  * has already selected an active result relation...
 616                                  */
 617                                 estate->es_junkFilter =
 618                                         estate->es_result_relation_info->ri_junkFilter;
 619                         }
 620                         else
 621                         {
 622                                 /* Normal case with just one JunkFilter */
 623                                 JunkFilter *j;
 624
 625                                 j = ExecInitJunkFilter(planstate->plan->targetlist,
 626                                                                            tupType,
 627                                                           ExecAllocTableSlot(estate->es_tupleTable));
 628                                 estate->es_junkFilter = j;
 629                                 if (estate->es_result_relation_info)
 630                                         estate->es_result_relation_info->ri_junkFilter = j;
 631
 632                                 /* For SELECT, want to return the cleaned tuple type */
 633                                 if (operation == CMD_SELECT)
 634                                         tupType = j->jf_cleanTupType;
 635                         }
 636                 }
 637                 else
 638                         estate->es_junkFilter = NULL;
 639         }
 640
 641         /*
 642          * initialize the "into" relation
 643          */
 644         intoRelationDesc = (Relation) NULL;
 645
 646         if (operation == CMD_SELECT)
 647         {
 648                 if (!parseTree->isPortal)
 649                 {
 650                         /*
 651                          * a select into table --- need to create the "into" table
 652                          */
 653                         if (parseTree->into != NULL)
 654                         {
 655                                 char       *intoName;
 656                                 Oid                     namespaceId;
 657                                 AclResult       aclresult;
 658                                 Oid                     intoRelationId;
 659                                 TupleDesc       tupdesc;
 660
 661                                 /*
 662                                  * find namespace to create in, check permissions
 663                                  */
 664                                 intoName = parseTree->into->relname;
 665                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 666
 667                                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 668                                                                                                   ACL_CREATE);
 669                                 if (aclresult != ACLCHECK_OK)
 670                                         aclcheck_error(aclresult,
 671                                                                    get_namespace_name(namespaceId));
 672
 673                                 /*
 674                                  * have to copy tupType to get rid of constraints
 675                                  */
 676                                 tupdesc = CreateTupleDescCopy(tupType);
 677
 678                                 /*
 679                                  * Formerly we forced the output table to have OIDs, but
 680                                  * as of 7.3 it will not have OIDs, because it's too late
 681                                  * here to change the tupdescs of the already-initialized
 682                                  * plan tree.  (Perhaps we could recurse and change them
 683                                  * all, but it's not really worth the trouble IMHO...)
 684                                  */
 685
 686                                 intoRelationId =
 687                                         heap_create_with_catalog(intoName,
 688                                                                                          namespaceId,
 689                                                                                          tupdesc,
 690                                                                                          RELKIND_RELATION,
 691                                                                                          false,
 692                                                                                          ONCOMMIT_NOOP,
 693                                                                                          allowSystemTableMods);
 694
 695                                 FreeTupleDesc(tupdesc);
 696
 697                                 /*
 698                                  * Advance command counter so that the newly-created
 699                                  * relation's catalog tuples will be visible to heap_open.
 700                                  */
 701                                 CommandCounterIncrement();
 702
 703                                 /*
 704                                  * If necessary, create a TOAST table for the into
 705                                  * relation. Note that AlterTableCreateToastTable ends
 706                                  * with CommandCounterIncrement(), so that the TOAST table
 707                                  * will be visible for insertion.
 708                                  */
 709                                 AlterTableCreateToastTable(intoRelationId, true);
 710
 711                                 intoRelationDesc = heap_open(intoRelationId,
 712                                                                                          AccessExclusiveLock);
 713                         }
 714                 }
 715         }
 716
 717         estate->es_into_relation_descriptor = intoRelationDesc;
 718
 719         queryDesc->tupDesc = tupType;
 720         queryDesc->planstate = planstate;
 721 }
 722
 723 /*
 724  * Initialize ResultRelInfo data for one result relation
 725  */
 726 static void
 727 initResultRelInfo(ResultRelInfo *resultRelInfo,
 728                                   Index resultRelationIndex,
 729                                   List *rangeTable,
 730                                   CmdType operation)
 731 {
 732         Oid                     resultRelationOid;
 733         Relation        resultRelationDesc;
 734
 735         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 736         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 737
 738         switch (resultRelationDesc->rd_rel->relkind)
 739         {
 740                 case RELKIND_SEQUENCE:
 741                         elog(ERROR, "You can't change sequence relation %s",
 742                                  RelationGetRelationName(resultRelationDesc));
 743                         break;
 744                 case RELKIND_TOASTVALUE:
 745                         elog(ERROR, "You can't change toast relation %s",
 746                                  RelationGetRelationName(resultRelationDesc));
 747                         break;
 748                 case RELKIND_VIEW:
 749                         elog(ERROR, "You can't change view relation %s",
 750                                  RelationGetRelationName(resultRelationDesc));
 751                         break;
 752         }
 753
 754         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 755         resultRelInfo->type = T_ResultRelInfo;
 756         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 757         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 758         resultRelInfo->ri_NumIndices = 0;
 759         resultRelInfo->ri_IndexRelationDescs = NULL;
 760         resultRelInfo->ri_IndexRelationInfo = NULL;
 761         /* make a copy so as not to depend on relcache info not changing... */
 762         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 763         resultRelInfo->ri_TrigFunctions = NULL;
 764         resultRelInfo->ri_ConstraintExprs = NULL;
 765         resultRelInfo->ri_junkFilter = NULL;
 766
 767         /*
 768          * If there are indices on the result relation, open them and save
 769          * descriptors in the result relation info, so that we can add new
 770          * index entries for the tuples we add/update.  We need not do this
 771          * for a DELETE, however, since deletion doesn't affect indexes.
 772          */
 773         if (resultRelationDesc->rd_rel->relhasindex &&
 774                 operation != CMD_DELETE)
 775                 ExecOpenIndices(resultRelInfo);
 776 }
 777
 778 /* ----------------------------------------------------------------
 779  *              ExecEndPlan
 780  *
 781  *              Cleans up the query plan -- closes files and frees up storage
 782  *
 783  * NOTE: we are no longer very worried about freeing storage per se
 784  * in this code; FreeExecutorState should be guaranteed to release all
 785  * memory that needs to be released.  What we are worried about doing
 786  * is closing relations and dropping buffer pins.  Thus, for example,
 787  * tuple tables must be cleared or dropped to ensure pins are released.
 788  * ----------------------------------------------------------------
 789  */
 790 void
 791 ExecEndPlan(PlanState *planstate, EState *estate)
 792 {
 793         ResultRelInfo *resultRelInfo;
 794         int                     i;
 795         List       *l;
 796
 797         /*
 798          * shut down any PlanQual processing we were doing
 799          */
 800         if (estate->es_evalPlanQual != NULL)
 801                 EndEvalPlanQual(estate);
 802
 803         /*
 804          * shut down the node-type-specific query processing
 805          */
 806         ExecEndNode(planstate);
 807
 808         /*
 809          * destroy the executor "tuple" table.
 810          */
 811         ExecDropTupleTable(estate->es_tupleTable, true);
 812         estate->es_tupleTable = NULL;
 813
 814         /*
 815          * close the result relation(s) if any, but hold locks until xact
 816          * commit.
 817          */
 818         resultRelInfo = estate->es_result_relations;
 819         for (i = estate->es_num_result_relations; i > 0; i--)
 820         {
 821                 /* Close indices and then the relation itself */
 822                 ExecCloseIndices(resultRelInfo);
 823                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 824                 resultRelInfo++;
 825         }
 826
 827         /*
 828          * close the "into" relation if necessary, again keeping lock
 829          */
 830         if (estate->es_into_relation_descriptor != NULL)
 831                 heap_close(estate->es_into_relation_descriptor, NoLock);
 832
 833         /*
 834          * close any relations selected FOR UPDATE, again keeping locks
 835          */
 836         foreach(l, estate->es_rowMark)
 837         {
 838                 execRowMark *erm = lfirst(l);
 839
 840                 heap_close(erm->relation, NoLock);
 841         }
 842 }
 843
 844 /* ----------------------------------------------------------------
 845  *              ExecutePlan
 846  *
 847  *              processes the query plan to retrieve 'numberTuples' tuples in the
 848  *              direction specified.
 849  *
 850  *              Retrieves all tuples if numberTuples is 0
 851  *
 852  *              result is either a slot containing the last tuple in the case
 853  *              of a SELECT or NULL otherwise.
 854  *
 855  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 856  * user can see it
 857  * ----------------------------------------------------------------
 858  */
 859 static TupleTableSlot *
 860 ExecutePlan(EState *estate,
 861                         PlanState *planstate,
 862                         CmdType operation,
 863                         long numberTuples,
 864                         ScanDirection direction,
 865                         DestReceiver *destfunc)
 866 {
 867         JunkFilter                      *junkfilter;
 868         TupleTableSlot          *slot;
 869         ItemPointer                      tupleid = NULL;
 870         ItemPointerData          tuple_ctid;
 871         long                             current_tuple_count;
 872         TupleTableSlot          *result;
 873
 874         /*
 875          * initialize local variables
 876          */
 877         slot = NULL;
 878         current_tuple_count = 0;
 879         result = NULL;
 880
 881         /*
 882          * Set the direction.
 883          */
 884         estate->es_direction = direction;
 885
 886         /*
 887          * Process BEFORE EACH STATEMENT triggers
 888          */
 889         switch (operation)
 890         {
 891                 case CMD_UPDATE:
 892                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 893                         break;
 894                 case CMD_DELETE:
 895                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 896                         break;
 897                 case CMD_INSERT:
 898                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 899                         break;
 900                 default:
 901                         /* do nothing */
 902                         break;
 903         }
 904
 905         /*
 906          * Loop until we've processed the proper number of tuples from the
 907          * plan.
 908          */
 909
 910         for (;;)
 911         {
 912                 /* Reset the per-output-tuple exprcontext */
 913                 ResetPerTupleExprContext(estate);
 914
 915                 /*
 916                  * Execute the plan and obtain a tuple
 917                  */
 918 lnext:  ;
 919                 if (estate->es_useEvalPlan)
 920                 {
 921                         slot = EvalPlanQualNext(estate);
 922                         if (TupIsNull(slot))
 923                                 slot = ExecProcNode(planstate);
 924                 }
 925                 else
 926                         slot = ExecProcNode(planstate);
 927
 928                 /*
 929                  * if the tuple is null, then we assume there is nothing more to
 930                  * process so we just return null...
 931                  */
 932                 if (TupIsNull(slot))
 933                 {
 934                         result = NULL;
 935                         break;
 936                 }
 937
 938                 /*
 939                  * if we have a junk filter, then project a new tuple with the
 940                  * junk removed.
 941                  *
 942                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 943                  * (Formerly, we stored it back over the "dirty" tuple, which is
 944                  * WRONG because that tuple slot has the wrong descriptor.)
 945                  *
 946                  * Also, extract all the junk information we need.
 947                  */
 948                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 949                 {
 950                         Datum           datum;
 951                         HeapTuple       newTuple;
 952                         bool            isNull;
 953
 954                         /*
 955                          * extract the 'ctid' junk attribute.
 956                          */
 957                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 958                         {
 959                                 if (!ExecGetJunkAttribute(junkfilter,
 960                                                                                   slot,
 961                                                                                   "ctid",
 962                                                                                   &datum,
 963                                                                                   &isNull))
 964                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 965
 966                                 /* shouldn't ever get a null result... */
 967                                 if (isNull)
 968                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 969
 970                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 971                                 tuple_ctid = *tupleid;  /* make sure we don't free the
 972                                                                                  * ctid!! */
 973                                 tupleid = &tuple_ctid;
 974                         }
 975                         else if (estate->es_rowMark != NIL)
 976                         {
 977                                 List       *l;
 978
 979                 lmark:  ;
 980                                 foreach(l, estate->es_rowMark)
 981                                 {
 982                                         execRowMark *erm = lfirst(l);
 983                                         Buffer          buffer;
 984                                         HeapTupleData tuple;
 985                                         TupleTableSlot *newSlot;
 986                                         int                     test;
 987
 988                                         if (!ExecGetJunkAttribute(junkfilter,
 989                                                                                           slot,
 990                                                                                           erm->resname,
 991                                                                                           &datum,
 992                                                                                           &isNull))
 993                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
 994                                                          erm->resname);
 995
 996                                         /* shouldn't ever get a null result... */
 997                                         if (isNull)
 998                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
 999                                                          erm->resname);
1000
1001                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1002                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1003                                                                                         estate->es_snapshot->curcid);
1004                                         ReleaseBuffer(buffer);
1005                                         switch (test)
1006                                         {
1007                                                 case HeapTupleSelfUpdated:
1008                                                         /* treat it as deleted; do not process */
1009                                                         goto lnext;
1010
1011                                                 case HeapTupleMayBeUpdated:
1012                                                         break;
1013
1014                                                 case HeapTupleUpdated:
1015                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1016                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1017                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1018                                                                   (ItemPointer) DatumGetPointer(datum))))
1019                                                         {
1020                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1021                                                                 if (!(TupIsNull(newSlot)))
1022                                                                 {
1023                                                                         slot = newSlot;
1024                                                                         estate->es_useEvalPlan = true;
1025                                                                         goto lmark;
1026                                                                 }
1027                                                         }
1028
1029                                                         /*
1030                                                          * if tuple was deleted or PlanQual failed for
1031                                                          * updated tuple - we must not return this
1032                                                          * tuple!
1033                                                          */
1034                                                         goto lnext;
1035
1036                                                 default:
1037                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1038                                                         return (NULL);
1039                                         }
1040                                 }
1041                         }
1042
1043                         /*
1044                          * Finally create a new "clean" tuple with all junk attributes
1045                          * removed
1046                          */
1047                         newTuple = ExecRemoveJunk(junkfilter, slot);
1048
1049                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1050                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1051                                                                   InvalidBuffer,                /* this tuple has no
1052                                                                                                                  * buffer */
1053                                                                   true);                /* tuple should be pfreed */
1054                 }
1055
1056                 /*
1057                  * now that we have a tuple, do the appropriate thing with it..
1058                  * either return it to the user, add it to a relation someplace,
1059                  * delete it from a relation, or modify some of its attributes.
1060                  */
1061                 switch (operation)
1062                 {
1063                         case CMD_SELECT:
1064                                 ExecSelect(slot,        /* slot containing tuple */
1065                                                    destfunc,    /* destination's tuple-receiver
1066                                                                                  * obj */
1067                                                    estate);
1068                                 result = slot;
1069                                 break;
1070
1071                         case CMD_INSERT:
1072                                 ExecInsert(slot, tupleid, estate);
1073                                 result = NULL;
1074                                 break;
1075
1076                         case CMD_DELETE:
1077                                 ExecDelete(slot, tupleid, estate);
1078                                 result = NULL;
1079                                 break;
1080
1081                         case CMD_UPDATE:
1082                                 ExecUpdate(slot, tupleid, estate);
1083                                 result = NULL;
1084                                 break;
1085
1086                         default:
1087                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1088                                 result = NULL;
1089                                 break;
1090                 }
1091
1092                 /*
1093                  * check our tuple count.. if we've processed the proper number
1094                  * then quit, else loop again and process more tuples.  Zero
1095                  * numberTuples means no limit.
1096                  */
1097                 current_tuple_count++;
1098                 if (numberTuples && numberTuples == current_tuple_count)
1099                         break;
1100         }
1101
1102         /*
1103          * Process AFTER EACH STATEMENT triggers
1104          */
1105         switch (operation)
1106         {
1107                 case CMD_UPDATE:
1108                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1109                         break;
1110                 case CMD_DELETE:
1111                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1112                         break;
1113                 case CMD_INSERT:
1114                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1115                         break;
1116                 default:
1117                         /* do nothing */
1118                         break;
1119         }
1120
1121         /*
1122          * here, result is either a slot containing a tuple in the case of a
1123          * SELECT or NULL otherwise.
1124          */
1125         return result;
1126 }
1127
1128 /* ----------------------------------------------------------------
1129  *              ExecSelect
1130  *
1131  *              SELECTs are easy.. we just pass the tuple to the appropriate
1132  *              print function.  The only complexity is when we do a
1133  *              "SELECT INTO", in which case we insert the tuple into
1134  *              the appropriate relation (note: this is a newly created relation
1135  *              so we don't need to worry about indices or locks.)
1136  * ----------------------------------------------------------------
1137  */
1138 static void
1139 ExecSelect(TupleTableSlot *slot,
1140                    DestReceiver *destfunc,
1141                    EState *estate)
1142 {
1143         HeapTuple       tuple;
1144         TupleDesc       attrtype;
1145
1146         /*
1147          * get the heap tuple out of the tuple table slot
1148          */
1149         tuple = slot->val;
1150         attrtype = slot->ttc_tupleDescriptor;
1151
1152         /*
1153          * insert the tuple into the "into relation"
1154          */
1155         if (estate->es_into_relation_descriptor != NULL)
1156         {
1157                 heap_insert(estate->es_into_relation_descriptor, tuple,
1158                                         estate->es_snapshot->curcid);
1159                 IncrAppended();
1160         }
1161
1162         /*
1163          * send the tuple to the front end (or the screen)
1164          */
1165         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1166         IncrRetrieved();
1167         (estate->es_processed)++;
1168 }
1169
1170 /* ----------------------------------------------------------------
1171  *              ExecInsert
1172  *
1173  *              INSERTs are trickier.. we have to insert the tuple into
1174  *              the base relation and insert appropriate tuples into the
1175  *              index relations.
1176  * ----------------------------------------------------------------
1177  */
1178 static void
1179 ExecInsert(TupleTableSlot *slot,
1180                    ItemPointer tupleid,
1181                    EState *estate)
1182 {
1183         HeapTuple       tuple;
1184         ResultRelInfo *resultRelInfo;
1185         Relation        resultRelationDesc;
1186         int                     numIndices;
1187         Oid                     newId;
1188
1189         /*
1190          * get the heap tuple out of the tuple table slot
1191          */
1192         tuple = slot->val;
1193
1194         /*
1195          * get information on the (current) result relation
1196          */
1197         resultRelInfo = estate->es_result_relation_info;
1198         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1199
1200         /* BEFORE ROW INSERT Triggers */
1201         if (resultRelInfo->ri_TrigDesc &&
1202                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1203         {
1204                 HeapTuple       newtuple;
1205
1206                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1207
1208                 if (newtuple == NULL)   /* "do nothing" */
1209                         return;
1210
1211                 if (newtuple != tuple)  /* modified by Trigger(s) */
1212                 {
1213                         /*
1214                          * Insert modified tuple into tuple table slot, replacing the
1215                          * original.  We assume that it was allocated in per-tuple
1216                          * memory context, and therefore will go away by itself. The
1217                          * tuple table slot should not try to clear it.
1218                          */
1219                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1220                         tuple = newtuple;
1221                 }
1222         }
1223
1224         /*
1225          * Check the constraints of the tuple
1226          */
1227         if (resultRelationDesc->rd_att->constr)
1228                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1229
1230         /*
1231          * insert the tuple
1232          */
1233         newId = heap_insert(resultRelationDesc, tuple,
1234                                                 estate->es_snapshot->curcid);
1235
1236         IncrAppended();
1237         (estate->es_processed)++;
1238         estate->es_lastoid = newId;
1239         setLastTid(&(tuple->t_self));
1240
1241         /*
1242          * process indices
1243          *
1244          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1245          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1246          * field.
1247          */
1248         numIndices = resultRelInfo->ri_NumIndices;
1249         if (numIndices > 0)
1250                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1251
1252         /* AFTER ROW INSERT Triggers */
1253         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1254 }
1255
1256 /* ----------------------------------------------------------------
1257  *              ExecDelete
1258  *
1259  *              DELETE is like UPDATE, we delete the tuple and its
1260  *              index tuples.
1261  * ----------------------------------------------------------------
1262  */
1263 static void
1264 ExecDelete(TupleTableSlot *slot,
1265                    ItemPointer tupleid,
1266                    EState *estate)
1267 {
1268         ResultRelInfo *resultRelInfo;
1269         Relation        resultRelationDesc;
1270         ItemPointerData ctid;
1271         int                     result;
1272
1273         /*
1274          * get information on the (current) result relation
1275          */
1276         resultRelInfo = estate->es_result_relation_info;
1277         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1278
1279         /* BEFORE ROW DELETE Triggers */
1280         if (resultRelInfo->ri_TrigDesc &&
1281           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1282         {
1283                 bool            dodelete;
1284
1285                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1286
1287                 if (!dodelete)                  /* "do nothing" */
1288                         return;
1289         }
1290
1291         /*
1292          * delete the tuple
1293          */
1294 ldelete:;
1295         result = heap_delete(resultRelationDesc, tupleid,
1296                                                  &ctid,
1297                                                  estate->es_snapshot->curcid);
1298         switch (result)
1299         {
1300                 case HeapTupleSelfUpdated:
1301                         /* already deleted by self; nothing to do */
1302                         return;
1303
1304                 case HeapTupleMayBeUpdated:
1305                         break;
1306
1307                 case HeapTupleUpdated:
1308                         if (XactIsoLevel == XACT_SERIALIZABLE)
1309                                 elog(ERROR, "Can't serialize access due to concurrent update");
1310                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1311                         {
1312                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1313                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1314
1315                                 if (!TupIsNull(epqslot))
1316                                 {
1317                                         *tupleid = ctid;
1318                                         goto ldelete;
1319                                 }
1320                         }
1321                         /* tuple already deleted; nothing to do */
1322                         return;
1323
1324                 default:
1325                         elog(ERROR, "Unknown status %u from heap_delete", result);
1326                         return;
1327         }
1328
1329         IncrDeleted();
1330         (estate->es_processed)++;
1331
1332         /*
1333          * Note: Normally one would think that we have to delete index tuples
1334          * associated with the heap tuple now..
1335          *
1336          * ... but in POSTGRES, we have no need to do this because the vacuum
1337          * daemon automatically opens an index scan and deletes index tuples
1338          * when it finds deleted heap tuples. -cim 9/27/89
1339          */
1340
1341         /* AFTER ROW DELETE Triggers */
1342         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1343 }
1344
1345 /* ----------------------------------------------------------------
1346  *              ExecUpdate
1347  *
1348  *              note: we can't run UPDATE queries with transactions
1349  *              off because UPDATEs are actually INSERTs and our
1350  *              scan will mistakenly loop forever, updating the tuple
1351  *              it just inserted..      This should be fixed but until it
1352  *              is, we don't want to get stuck in an infinite loop
1353  *              which corrupts your database..
1354  * ----------------------------------------------------------------
1355  */
1356 static void
1357 ExecUpdate(TupleTableSlot *slot,
1358                    ItemPointer tupleid,
1359                    EState *estate)
1360 {
1361         HeapTuple       tuple;
1362         ResultRelInfo *resultRelInfo;
1363         Relation        resultRelationDesc;
1364         ItemPointerData ctid;
1365         int                     result;
1366         int                     numIndices;
1367
1368         /*
1369          * abort the operation if not running transactions
1370          */
1371         if (IsBootstrapProcessingMode())
1372         {
1373                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1374                 return;
1375         }
1376
1377         /*
1378          * get the heap tuple out of the tuple table slot
1379          */
1380         tuple = slot->val;
1381
1382         /*
1383          * get information on the (current) result relation
1384          */
1385         resultRelInfo = estate->es_result_relation_info;
1386         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1387
1388         /* BEFORE ROW UPDATE Triggers */
1389         if (resultRelInfo->ri_TrigDesc &&
1390           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1391         {
1392                 HeapTuple       newtuple;
1393
1394                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1395                                                                                 tupleid, tuple);
1396
1397                 if (newtuple == NULL)   /* "do nothing" */
1398                         return;
1399
1400                 if (newtuple != tuple)  /* modified by Trigger(s) */
1401                 {
1402                         /*
1403                          * Insert modified tuple into tuple table slot, replacing the
1404                          * original.  We assume that it was allocated in per-tuple
1405                          * memory context, and therefore will go away by itself. The
1406                          * tuple table slot should not try to clear it.
1407                          */
1408                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1409                         tuple = newtuple;
1410                 }
1411         }
1412
1413         /*
1414          * Check the constraints of the tuple
1415          *
1416          * If we generate a new candidate tuple after EvalPlanQual testing, we
1417          * must loop back here and recheck constraints.  (We don't need to
1418          * redo triggers, however.      If there are any BEFORE triggers then
1419          * trigger.c will have done mark4update to lock the correct tuple, so
1420          * there's no need to do them again.)
1421          */
1422 lreplace:;
1423         if (resultRelationDesc->rd_att->constr)
1424                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1425
1426         /*
1427          * replace the heap tuple
1428          */
1429         result = heap_update(resultRelationDesc, tupleid, tuple,
1430                                                  &ctid,
1431                                                  estate->es_snapshot->curcid);
1432         switch (result)
1433         {
1434                 case HeapTupleSelfUpdated:
1435                         /* already deleted by self; nothing to do */
1436                         return;
1437
1438                 case HeapTupleMayBeUpdated:
1439                         break;
1440
1441                 case HeapTupleUpdated:
1442                         if (XactIsoLevel == XACT_SERIALIZABLE)
1443                                 elog(ERROR, "Can't serialize access due to concurrent update");
1444                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1445                         {
1446                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1447                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1448
1449                                 if (!TupIsNull(epqslot))
1450                                 {
1451                                         *tupleid = ctid;
1452                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1453                                         slot = ExecStoreTuple(tuple,
1454                                                                         estate->es_junkFilter->jf_resultSlot,
1455                                                                                   InvalidBuffer, true);
1456                                         goto lreplace;
1457                                 }
1458                         }
1459                         /* tuple already deleted; nothing to do */
1460                         return;
1461
1462                 default:
1463                         elog(ERROR, "Unknown status %u from heap_update", result);
1464                         return;
1465         }
1466
1467         IncrReplaced();
1468         (estate->es_processed)++;
1469
1470         /*
1471          * Note: instead of having to update the old index tuples associated
1472          * with the heap tuple, all we do is form and insert new index tuples.
1473          * This is because UPDATEs are actually DELETEs and INSERTs and index
1474          * tuple deletion is done automagically by the vacuum daemon. All we
1475          * do is insert new index tuples.  -cim 9/27/89
1476          */
1477
1478         /*
1479          * process indices
1480          *
1481          * heap_update updates a tuple in the base relation by invalidating it
1482          * and then inserting a new tuple to the relation.      As a side effect,
1483          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1484          * field.  So we now insert index tuples using the new tupleid stored
1485          * there.
1486          */
1487
1488         numIndices = resultRelInfo->ri_NumIndices;
1489         if (numIndices > 0)
1490                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1491
1492         /* AFTER ROW UPDATE Triggers */
1493         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1494 }
1495
1496 static char *
1497 ExecRelCheck(ResultRelInfo *resultRelInfo,
1498                          TupleTableSlot *slot, EState *estate)
1499 {
1500         Relation        rel = resultRelInfo->ri_RelationDesc;
1501         int                     ncheck = rel->rd_att->constr->num_check;
1502         ConstrCheck *check = rel->rd_att->constr->check;
1503         ExprContext *econtext;
1504         MemoryContext oldContext;
1505         List       *qual;
1506         int                     i;
1507
1508         /*
1509          * If first time through for this result relation, build expression
1510          * nodetrees for rel's constraint expressions.  Keep them in the
1511          * per-query memory context so they'll survive throughout the query.
1512          */
1513         if (resultRelInfo->ri_ConstraintExprs == NULL)
1514         {
1515                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1516                 resultRelInfo->ri_ConstraintExprs =
1517                         (List **) palloc(ncheck * sizeof(List *));
1518                 for (i = 0; i < ncheck; i++)
1519                 {
1520                         qual = (List *) stringToNode(check[i].ccbin);
1521                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1522                                 ExecPrepareExpr((Expr *) qual, estate);
1523                 }
1524                 MemoryContextSwitchTo(oldContext);
1525         }
1526
1527         /*
1528          * We will use the EState's per-tuple context for evaluating
1529          * constraint expressions (creating it if it's not already there).
1530          */
1531         econtext = GetPerTupleExprContext(estate);
1532
1533         /* Arrange for econtext's scan tuple to be the tuple under test */
1534         econtext->ecxt_scantuple = slot;
1535
1536         /* And evaluate the constraints */
1537         for (i = 0; i < ncheck; i++)
1538         {
1539                 qual = resultRelInfo->ri_ConstraintExprs[i];
1540
1541                 /*
1542                  * NOTE: SQL92 specifies that a NULL result from a constraint
1543                  * expression is not to be treated as a failure.  Therefore, tell
1544                  * ExecQual to return TRUE for NULL.
1545                  */
1546                 if (!ExecQual(qual, econtext, true))
1547                         return check[i].ccname;
1548         }
1549
1550         /* NULL result means no error */
1551         return (char *) NULL;
1552 }
1553
1554 void
1555 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1556                                 TupleTableSlot *slot, EState *estate)
1557 {
1558         Relation        rel = resultRelInfo->ri_RelationDesc;
1559         HeapTuple       tuple = slot->val;
1560         TupleConstr *constr = rel->rd_att->constr;
1561
1562         Assert(constr);
1563
1564         if (constr->has_not_null)
1565         {
1566                 int                     natts = rel->rd_att->natts;
1567                 int                     attrChk;
1568
1569                 for (attrChk = 1; attrChk <= natts; attrChk++)
1570                 {
1571                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1572                                 heap_attisnull(tuple, attrChk))
1573                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1574                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1575                 }
1576         }
1577
1578         if (constr->num_check > 0)
1579         {
1580                 char       *failed;
1581
1582                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1583                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1584                                  caller, failed, RelationGetRelationName(rel));
1585         }
1586 }
1587
1588 /*
1589  * Check a modified tuple to see if we want to process its updated version
1590  * under READ COMMITTED rules.
1591  *
1592  * See backend/executor/README for some info about how this works.
1593  */
1594 TupleTableSlot *
1595 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1596 {
1597         evalPlanQual *epq;
1598         EState     *epqstate;
1599         Relation        relation;
1600         HeapTupleData tuple;
1601         HeapTuple       copyTuple = NULL;
1602         bool            endNode;
1603
1604         Assert(rti != 0);
1605
1606         /*
1607          * find relation containing target tuple
1608          */
1609         if (estate->es_result_relation_info != NULL &&
1610                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1611                 relation = estate->es_result_relation_info->ri_RelationDesc;
1612         else
1613         {
1614                 List       *l;
1615
1616                 relation = NULL;
1617                 foreach(l, estate->es_rowMark)
1618                 {
1619                         if (((execRowMark *) lfirst(l))->rti == rti)
1620                         {
1621                                 relation = ((execRowMark *) lfirst(l))->relation;
1622                                 break;
1623                         }
1624                 }
1625                 if (relation == NULL)
1626                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1627         }
1628
1629         /*
1630          * fetch tid tuple
1631          *
1632          * Loop here to deal with updated or busy tuples
1633          */
1634         tuple.t_self = *tid;
1635         for (;;)
1636         {
1637                 Buffer          buffer;
1638
1639                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1640                 {
1641                         TransactionId xwait = SnapshotDirty->xmax;
1642
1643                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1644                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1645
1646                         /*
1647                          * If tuple is being updated by other transaction then we have
1648                          * to wait for its commit/abort.
1649                          */
1650                         if (TransactionIdIsValid(xwait))
1651                         {
1652                                 ReleaseBuffer(buffer);
1653                                 XactLockTableWait(xwait);
1654                                 continue;
1655                         }
1656
1657                         /*
1658                          * We got tuple - now copy it for use by recheck query.
1659                          */
1660                         copyTuple = heap_copytuple(&tuple);
1661                         ReleaseBuffer(buffer);
1662                         break;
1663                 }
1664
1665                 /*
1666                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1667                  * Note that it's possible to get invalid SnapshotDirty->tid if
1668                  * tuple updated by this transaction. Have we to check this ?
1669                  */
1670                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1671                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1672                 {
1673                         /* updated, so look at the updated copy */
1674                         tuple.t_self = SnapshotDirty->tid;
1675                         continue;
1676                 }
1677
1678                 /*
1679                  * Deleted or updated by this transaction; forget it.
1680                  */
1681                 return NULL;
1682         }
1683
1684         /*
1685          * For UPDATE/DELETE we have to return tid of actual row we're
1686          * executing PQ for.
1687          */
1688         *tid = tuple.t_self;
1689
1690         /*
1691          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1692          */
1693         epq = estate->es_evalPlanQual;
1694         endNode = true;
1695
1696         if (epq != NULL && epq->rti == 0)
1697         {
1698                 /* Top PQ stack entry is idle, so re-use it */
1699                 Assert(!(estate->es_useEvalPlan) && epq->next == NULL);
1700                 epq->rti = rti;
1701                 endNode = false;
1702         }
1703
1704         /*
1705          * If this is request for another RTE - Ra, - then we have to check
1706          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1707          * updated again and we have to re-start old execution for Ra and
1708          * forget all what we done after Ra was suspended. Cool? -:))
1709          */
1710         if (epq != NULL && epq->rti != rti &&
1711                 epq->estate->es_evTuple[rti - 1] != NULL)
1712         {
1713                 do
1714                 {
1715                         evalPlanQual *oldepq;
1716
1717                         /* stop execution */
1718                         EvalPlanQualStop(epq);
1719                         /* pop previous PlanQual from the stack */
1720                         oldepq = epq->next;
1721                         Assert(oldepq && oldepq->rti != 0);
1722                         /* push current PQ to freePQ stack */
1723                         oldepq->free = epq;
1724                         epq = oldepq;
1725                         estate->es_evalPlanQual = epq;
1726                 } while (epq->rti != rti);
1727         }
1728
1729         /*
1730          * If we are requested for another RTE then we have to suspend
1731          * execution of current PlanQual and start execution for new one.
1732          */
1733         if (epq == NULL || epq->rti != rti)
1734         {
1735                 /* try to reuse plan used previously */
1736                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1737
1738                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1739                 {
1740                         newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual));
1741                         newepq->free = NULL;
1742                         newepq->estate = NULL;
1743                         newepq->planstate = NULL;
1744                 }
1745                 else
1746                 {
1747                         /* recycle previously used PlanQual */
1748                         Assert(newepq->estate == NULL);
1749                         epq->free = NULL;
1750                 }
1751                 /* push current PQ to the stack */
1752                 newepq->next = epq;
1753                 epq = newepq;
1754                 estate->es_evalPlanQual = epq;
1755                 epq->rti = rti;
1756                 endNode = false;
1757         }
1758
1759         Assert(epq->rti == rti);
1760
1761         /*
1762          * Ok - we're requested for the same RTE.  Unfortunately we still have
1763          * to end and restart execution of the plan, because ExecReScan
1764          * wouldn't ensure that upper plan nodes would reset themselves.  We
1765          * could make that work if insertion of the target tuple were
1766          * integrated with the Param mechanism somehow, so that the upper plan
1767          * nodes know that their children's outputs have changed.
1768          *
1769          * Note that the stack of free evalPlanQual nodes is quite useless at
1770          * the moment, since it only saves us from pallocing/releasing the
1771          * evalPlanQual nodes themselves.  But it will be useful once we
1772          * implement ReScan instead of end/restart for re-using PlanQual nodes.
1773          */
1774         if (endNode)
1775         {
1776                 /* stop execution */
1777                 EvalPlanQualStop(epq);
1778         }
1779
1780         /*
1781          * Initialize new recheck query.
1782          *
1783          * Note: if we were re-using PlanQual plans via ExecReScan, we'd need
1784          * to instead copy down changeable state from the top plan (including
1785          * es_result_relation_info, es_junkFilter) and reset locally changeable
1786          * state in the epq (including es_param_exec_vals, es_evTupleNull).
1787          */
1788         EvalPlanQualStart(epq, estate, epq->next);
1789
1790         /*
1791          * free old RTE' tuple, if any, and store target tuple where
1792          * relation's scan node will see it
1793          */
1794         epqstate = epq->estate;
1795         if (epqstate->es_evTuple[rti - 1] != NULL)
1796                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1797         epqstate->es_evTuple[rti - 1] = copyTuple;
1798
1799         return EvalPlanQualNext(estate);
1800 }
1801
1802 static TupleTableSlot *
1803 EvalPlanQualNext(EState *estate)
1804 {
1805         evalPlanQual *epq = estate->es_evalPlanQual;
1806         MemoryContext oldcontext;
1807         TupleTableSlot *slot;
1808
1809         Assert(epq->rti != 0);
1810
1811 lpqnext:;
1812         oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt);
1813         slot = ExecProcNode(epq->planstate);
1814         MemoryContextSwitchTo(oldcontext);
1815
1816         /*
1817          * No more tuples for this PQ. Continue previous one.
1818          */
1819         if (TupIsNull(slot))
1820         {
1821                 evalPlanQual *oldepq;
1822
1823                 /* stop execution */
1824                 EvalPlanQualStop(epq);
1825                 /* pop old PQ from the stack */
1826                 oldepq = epq->next;
1827                 if (oldepq == NULL)
1828                 {
1829                         /* this is the first (oldest) PQ - mark as free */
1830                         epq->rti = 0;
1831                         estate->es_useEvalPlan = false;
1832                         /* and continue Query execution */
1833                         return (NULL);
1834                 }
1835                 Assert(oldepq->rti != 0);
1836                 /* push current PQ to freePQ stack */
1837                 oldepq->free = epq;
1838                 epq = oldepq;
1839                 estate->es_evalPlanQual = epq;
1840                 goto lpqnext;
1841         }
1842
1843         return (slot);
1844 }
1845
1846 static void
1847 EndEvalPlanQual(EState *estate)
1848 {
1849         evalPlanQual *epq = estate->es_evalPlanQual;
1850
1851         if (epq->rti == 0)                      /* plans already shutdowned */
1852         {
1853                 Assert(epq->next == NULL);
1854                 return;
1855         }
1856
1857         for (;;)
1858         {
1859                 evalPlanQual *oldepq;
1860
1861                 /* stop execution */
1862                 EvalPlanQualStop(epq);
1863                 /* pop old PQ from the stack */
1864                 oldepq = epq->next;
1865                 if (oldepq == NULL)
1866                 {
1867                         /* this is the first (oldest) PQ - mark as free */
1868                         epq->rti = 0;
1869                         estate->es_useEvalPlan = false;
1870                         break;
1871                 }
1872                 Assert(oldepq->rti != 0);
1873                 /* push current PQ to freePQ stack */
1874                 oldepq->free = epq;
1875                 epq = oldepq;
1876                 estate->es_evalPlanQual = epq;
1877         }
1878 }
1879
1880 /*
1881  * Start execution of one level of PlanQual.
1882  *
1883  * This is a cut-down version of ExecutorStart(): we copy some state from
1884  * the top-level estate rather than initializing it fresh.
1885  */
1886 static void
1887 EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
1888 {
1889         EState     *epqstate;
1890         int                     rtsize;
1891         MemoryContext oldcontext;
1892
1893         rtsize = length(estate->es_range_table);
1894
1895         epq->estate = epqstate = CreateExecutorState();
1896
1897         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1898
1899         /*
1900          * The epqstates share the top query's copy of unchanging state such
1901          * as the snapshot, rangetable, result-rel info, and external Param info.
1902          * They need their own copies of local state, including a tuple table,
1903          * es_param_exec_vals, etc.
1904          */
1905         epqstate->es_direction = ForwardScanDirection;
1906         epqstate->es_snapshot = estate->es_snapshot;
1907         epqstate->es_range_table = estate->es_range_table;
1908         epqstate->es_result_relations = estate->es_result_relations;
1909         epqstate->es_num_result_relations = estate->es_num_result_relations;
1910         epqstate->es_result_relation_info = estate->es_result_relation_info;
1911         epqstate->es_junkFilter = estate->es_junkFilter;
1912         epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor;
1913         epqstate->es_param_list_info = estate->es_param_list_info;
1914         if (estate->es_topPlan->nParamExec > 0)
1915                 epqstate->es_param_exec_vals = (ParamExecData *)
1916                         palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
1917         epqstate->es_rowMark = estate->es_rowMark;
1918         epqstate->es_instrument = estate->es_instrument;
1919         epqstate->es_topPlan = estate->es_topPlan;
1920         /*
1921          * Each epqstate must have its own es_evTupleNull state, but
1922          * all the stack entries share es_evTuple state.  This allows
1923          * sub-rechecks to inherit the value being examined by an
1924          * outer recheck.
1925          */
1926         epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool));
1927         if (priorepq == NULL)
1928                 /* first PQ stack entry */
1929                 epqstate->es_evTuple = (HeapTuple *)
1930                         palloc0(rtsize * sizeof(HeapTuple));
1931         else
1932                 /* later stack entries share the same storage */
1933                 epqstate->es_evTuple = priorepq->estate->es_evTuple;
1934
1935         epqstate->es_tupleTable =
1936                 ExecCreateTupleTable(estate->es_tupleTable->size);
1937
1938         epq->planstate = ExecInitNode(estate->es_topPlan, epqstate);
1939
1940         MemoryContextSwitchTo(oldcontext);
1941 }
1942
1943 /*
1944  * End execution of one level of PlanQual.
1945  *
1946  * This is a cut-down version of ExecutorEnd(); basically we want to do most
1947  * of the normal cleanup, but *not* close result relations (which we are
1948  * just sharing from the outer query).
1949  */
1950 static void
1951 EvalPlanQualStop(evalPlanQual *epq)
1952 {
1953         EState     *epqstate = epq->estate;
1954         MemoryContext oldcontext;
1955
1956         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1957
1958         ExecEndNode(epq->planstate);
1959
1960         ExecDropTupleTable(epqstate->es_tupleTable, true);
1961         epqstate->es_tupleTable = NULL;
1962
1963         if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1964         {
1965                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1966                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1967         }
1968
1969         MemoryContextSwitchTo(oldcontext);
1970
1971         FreeExecutorState(epqstate);
1972
1973         epq->estate = NULL;
1974         epq->planstate = NULL;
1975 }