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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.195 2002/12/18 00:14:47 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, e.g. 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  *              Retrieves all tuples if numberTuples is 0
 850  *
 851  *              result is either a slot containing the last tuple in the case
 852  *              of a SELECT or NULL otherwise.
 853  *
 854  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 855  * user can see it
 856  * ----------------------------------------------------------------
 857  */
 858 static TupleTableSlot *
 859 ExecutePlan(EState *estate,
 860                         PlanState *planstate,
 861                         CmdType operation,
 862                         long numberTuples,
 863                         ScanDirection direction,
 864                         DestReceiver *destfunc)
 865 {
 866         JunkFilter                      *junkfilter;
 867         TupleTableSlot          *slot;
 868         ItemPointer                      tupleid = NULL;
 869         ItemPointerData          tuple_ctid;
 870         long                             current_tuple_count;
 871         TupleTableSlot          *result;
 872
 873         /*
 874          * initialize local variables
 875          */
 876         slot = NULL;
 877         current_tuple_count = 0;
 878         result = NULL;
 879
 880         /*
 881          * Set the direction.
 882          */
 883         estate->es_direction = direction;
 884
 885         /*
 886          * Process BEFORE EACH STATEMENT triggers
 887          */
 888         switch (operation)
 889         {
 890                 case CMD_UPDATE:
 891                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 892                         break;
 893                 case CMD_DELETE:
 894                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 895                         break;
 896                 case CMD_INSERT:
 897                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 898                         break;
 899                 default:
 900                         /* do nothing */
 901                         break;
 902         }
 903
 904         /*
 905          * Loop until we've processed the proper number of tuples from the
 906          * plan.
 907          */
 908
 909         for (;;)
 910         {
 911                 /* Reset the per-output-tuple exprcontext */
 912                 ResetPerTupleExprContext(estate);
 913
 914                 /*
 915                  * Execute the plan and obtain a tuple
 916                  */
 917 lnext:  ;
 918                 if (estate->es_useEvalPlan)
 919                 {
 920                         slot = EvalPlanQualNext(estate);
 921                         if (TupIsNull(slot))
 922                                 slot = ExecProcNode(planstate);
 923                 }
 924                 else
 925                         slot = ExecProcNode(planstate);
 926
 927                 /*
 928                  * if the tuple is null, then we assume there is nothing more to
 929                  * process so we just return null...
 930                  */
 931                 if (TupIsNull(slot))
 932                 {
 933                         result = NULL;
 934                         break;
 935                 }
 936
 937                 /*
 938                  * if we have a junk filter, then project a new tuple with the
 939                  * junk removed.
 940                  *
 941                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 942                  * (Formerly, we stored it back over the "dirty" tuple, which is
 943                  * WRONG because that tuple slot has the wrong descriptor.)
 944                  *
 945                  * Also, extract all the junk information we need.
 946                  */
 947                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 948                 {
 949                         Datum           datum;
 950                         HeapTuple       newTuple;
 951                         bool            isNull;
 952
 953                         /*
 954                          * extract the 'ctid' junk attribute.
 955                          */
 956                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 957                         {
 958                                 if (!ExecGetJunkAttribute(junkfilter,
 959                                                                                   slot,
 960                                                                                   "ctid",
 961                                                                                   &datum,
 962                                                                                   &isNull))
 963                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 964
 965                                 /* shouldn't ever get a null result... */
 966                                 if (isNull)
 967                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 968
 969                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 970                                 tuple_ctid = *tupleid;  /* make sure we don't free the
 971                                                                                  * ctid!! */
 972                                 tupleid = &tuple_ctid;
 973                         }
 974                         else if (estate->es_rowMark != NIL)
 975                         {
 976                                 List       *l;
 977
 978                 lmark:  ;
 979                                 foreach(l, estate->es_rowMark)
 980                                 {
 981                                         execRowMark *erm = lfirst(l);
 982                                         Buffer          buffer;
 983                                         HeapTupleData tuple;
 984                                         TupleTableSlot *newSlot;
 985                                         int                     test;
 986
 987                                         if (!ExecGetJunkAttribute(junkfilter,
 988                                                                                           slot,
 989                                                                                           erm->resname,
 990                                                                                           &datum,
 991                                                                                           &isNull))
 992                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
 993                                                          erm->resname);
 994
 995                                         /* shouldn't ever get a null result... */
 996                                         if (isNull)
 997                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
 998                                                          erm->resname);
 999
1000                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1001                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1002                                                                                         estate->es_snapshot->curcid);
1003                                         ReleaseBuffer(buffer);
1004                                         switch (test)
1005                                         {
1006                                                 case HeapTupleSelfUpdated:
1007                                                         /* treat it as deleted; do not process */
1008                                                         goto lnext;
1009
1010                                                 case HeapTupleMayBeUpdated:
1011                                                         break;
1012
1013                                                 case HeapTupleUpdated:
1014                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1015                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1016                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1017                                                                   (ItemPointer) DatumGetPointer(datum))))
1018                                                         {
1019                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1020                                                                 if (!(TupIsNull(newSlot)))
1021                                                                 {
1022                                                                         slot = newSlot;
1023                                                                         estate->es_useEvalPlan = true;
1024                                                                         goto lmark;
1025                                                                 }
1026                                                         }
1027
1028                                                         /*
1029                                                          * if tuple was deleted or PlanQual failed for
1030                                                          * updated tuple - we must not return this
1031                                                          * tuple!
1032                                                          */
1033                                                         goto lnext;
1034
1035                                                 default:
1036                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1037                                                         return (NULL);
1038                                         }
1039                                 }
1040                         }
1041
1042                         /*
1043                          * Finally create a new "clean" tuple with all junk attributes
1044                          * removed
1045                          */
1046                         newTuple = ExecRemoveJunk(junkfilter, slot);
1047
1048                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1049                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1050                                                                   InvalidBuffer,                /* this tuple has no
1051                                                                                                                  * buffer */
1052                                                                   true);                /* tuple should be pfreed */
1053                 }
1054
1055                 /*
1056                  * now that we have a tuple, do the appropriate thing with it..
1057                  * either return it to the user, add it to a relation someplace,
1058                  * delete it from a relation, or modify some of its attributes.
1059                  */
1060                 switch (operation)
1061                 {
1062                         case CMD_SELECT:
1063                                 ExecSelect(slot,        /* slot containing tuple */
1064                                                    destfunc,    /* destination's tuple-receiver
1065                                                                                  * obj */
1066                                                    estate);
1067                                 result = slot;
1068                                 break;
1069
1070                         case CMD_INSERT:
1071                                 ExecInsert(slot, tupleid, estate);
1072                                 result = NULL;
1073                                 break;
1074
1075                         case CMD_DELETE:
1076                                 ExecDelete(slot, tupleid, estate);
1077                                 result = NULL;
1078                                 break;
1079
1080                         case CMD_UPDATE:
1081                                 ExecUpdate(slot, tupleid, estate);
1082                                 result = NULL;
1083                                 break;
1084
1085                         default:
1086                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1087                                 result = NULL;
1088                                 break;
1089                 }
1090
1091                 /*
1092                  * check our tuple count.. if we've processed the proper number
1093                  * then quit, else loop again and process more tuples.  Zero
1094                  * number_tuples means no limit.
1095                  */
1096                 current_tuple_count++;
1097                 if (numberTuples == current_tuple_count)
1098                         break;
1099         }
1100
1101         /*
1102          * Process AFTER EACH STATEMENT triggers
1103          */
1104         switch (operation)
1105         {
1106                 case CMD_UPDATE:
1107                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1108                         break;
1109                 case CMD_DELETE:
1110                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1111                         break;
1112                 case CMD_INSERT:
1113                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1114                         break;
1115                 default:
1116                         /* do nothing */
1117                         break;
1118         }
1119
1120         /*
1121          * here, result is either a slot containing a tuple in the case of a
1122          * SELECT or NULL otherwise.
1123          */
1124         return result;
1125 }
1126
1127 /* ----------------------------------------------------------------
1128  *              ExecSelect
1129  *
1130  *              SELECTs are easy.. we just pass the tuple to the appropriate
1131  *              print function.  The only complexity is when we do a
1132  *              "SELECT INTO", in which case we insert the tuple into
1133  *              the appropriate relation (note: this is a newly created relation
1134  *              so we don't need to worry about indices or locks.)
1135  * ----------------------------------------------------------------
1136  */
1137 static void
1138 ExecSelect(TupleTableSlot *slot,
1139                    DestReceiver *destfunc,
1140                    EState *estate)
1141 {
1142         HeapTuple       tuple;
1143         TupleDesc       attrtype;
1144
1145         /*
1146          * get the heap tuple out of the tuple table slot
1147          */
1148         tuple = slot->val;
1149         attrtype = slot->ttc_tupleDescriptor;
1150
1151         /*
1152          * insert the tuple into the "into relation"
1153          */
1154         if (estate->es_into_relation_descriptor != NULL)
1155         {
1156                 heap_insert(estate->es_into_relation_descriptor, tuple,
1157                                         estate->es_snapshot->curcid);
1158                 IncrAppended();
1159         }
1160
1161         /*
1162          * send the tuple to the front end (or the screen)
1163          */
1164         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1165         IncrRetrieved();
1166         (estate->es_processed)++;
1167 }
1168
1169 /* ----------------------------------------------------------------
1170  *              ExecInsert
1171  *
1172  *              INSERTs are trickier.. we have to insert the tuple into
1173  *              the base relation and insert appropriate tuples into the
1174  *              index relations.
1175  * ----------------------------------------------------------------
1176  */
1177 static void
1178 ExecInsert(TupleTableSlot *slot,
1179                    ItemPointer tupleid,
1180                    EState *estate)
1181 {
1182         HeapTuple       tuple;
1183         ResultRelInfo *resultRelInfo;
1184         Relation        resultRelationDesc;
1185         int                     numIndices;
1186         Oid                     newId;
1187
1188         /*
1189          * get the heap tuple out of the tuple table slot
1190          */
1191         tuple = slot->val;
1192
1193         /*
1194          * get information on the (current) result relation
1195          */
1196         resultRelInfo = estate->es_result_relation_info;
1197         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1198
1199         /* BEFORE ROW INSERT Triggers */
1200         if (resultRelInfo->ri_TrigDesc &&
1201                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1202         {
1203                 HeapTuple       newtuple;
1204
1205                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1206
1207                 if (newtuple == NULL)   /* "do nothing" */
1208                         return;
1209
1210                 if (newtuple != tuple)  /* modified by Trigger(s) */
1211                 {
1212                         /*
1213                          * Insert modified tuple into tuple table slot, replacing the
1214                          * original.  We assume that it was allocated in per-tuple
1215                          * memory context, and therefore will go away by itself. The
1216                          * tuple table slot should not try to clear it.
1217                          */
1218                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1219                         tuple = newtuple;
1220                 }
1221         }
1222
1223         /*
1224          * Check the constraints of the tuple
1225          */
1226         if (resultRelationDesc->rd_att->constr)
1227                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1228
1229         /*
1230          * insert the tuple
1231          */
1232         newId = heap_insert(resultRelationDesc, tuple,
1233                                                 estate->es_snapshot->curcid);
1234
1235         IncrAppended();
1236         (estate->es_processed)++;
1237         estate->es_lastoid = newId;
1238         setLastTid(&(tuple->t_self));
1239
1240         /*
1241          * process indices
1242          *
1243          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1244          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1245          * field.
1246          */
1247         numIndices = resultRelInfo->ri_NumIndices;
1248         if (numIndices > 0)
1249                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1250
1251         /* AFTER ROW INSERT Triggers */
1252         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1253 }
1254
1255 /* ----------------------------------------------------------------
1256  *              ExecDelete
1257  *
1258  *              DELETE is like UPDATE, we delete the tuple and its
1259  *              index tuples.
1260  * ----------------------------------------------------------------
1261  */
1262 static void
1263 ExecDelete(TupleTableSlot *slot,
1264                    ItemPointer tupleid,
1265                    EState *estate)
1266 {
1267         ResultRelInfo *resultRelInfo;
1268         Relation        resultRelationDesc;
1269         ItemPointerData ctid;
1270         int                     result;
1271
1272         /*
1273          * get information on the (current) result relation
1274          */
1275         resultRelInfo = estate->es_result_relation_info;
1276         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1277
1278         /* BEFORE ROW DELETE Triggers */
1279         if (resultRelInfo->ri_TrigDesc &&
1280           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1281         {
1282                 bool            dodelete;
1283
1284                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1285
1286                 if (!dodelete)                  /* "do nothing" */
1287                         return;
1288         }
1289
1290         /*
1291          * delete the tuple
1292          */
1293 ldelete:;
1294         result = heap_delete(resultRelationDesc, tupleid,
1295                                                  &ctid,
1296                                                  estate->es_snapshot->curcid);
1297         switch (result)
1298         {
1299                 case HeapTupleSelfUpdated:
1300                         /* already deleted by self; nothing to do */
1301                         return;
1302
1303                 case HeapTupleMayBeUpdated:
1304                         break;
1305
1306                 case HeapTupleUpdated:
1307                         if (XactIsoLevel == XACT_SERIALIZABLE)
1308                                 elog(ERROR, "Can't serialize access due to concurrent update");
1309                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1310                         {
1311                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1312                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1313
1314                                 if (!TupIsNull(epqslot))
1315                                 {
1316                                         *tupleid = ctid;
1317                                         goto ldelete;
1318                                 }
1319                         }
1320                         /* tuple already deleted; nothing to do */
1321                         return;
1322
1323                 default:
1324                         elog(ERROR, "Unknown status %u from heap_delete", result);
1325                         return;
1326         }
1327
1328         IncrDeleted();
1329         (estate->es_processed)++;
1330
1331         /*
1332          * Note: Normally one would think that we have to delete index tuples
1333          * associated with the heap tuple now..
1334          *
1335          * ... but in POSTGRES, we have no need to do this because the vacuum
1336          * daemon automatically opens an index scan and deletes index tuples
1337          * when it finds deleted heap tuples. -cim 9/27/89
1338          */
1339
1340         /* AFTER ROW DELETE Triggers */
1341         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1342 }
1343
1344 /* ----------------------------------------------------------------
1345  *              ExecUpdate
1346  *
1347  *              note: we can't run UPDATE queries with transactions
1348  *              off because UPDATEs are actually INSERTs and our
1349  *              scan will mistakenly loop forever, updating the tuple
1350  *              it just inserted..      This should be fixed but until it
1351  *              is, we don't want to get stuck in an infinite loop
1352  *              which corrupts your database..
1353  * ----------------------------------------------------------------
1354  */
1355 static void
1356 ExecUpdate(TupleTableSlot *slot,
1357                    ItemPointer tupleid,
1358                    EState *estate)
1359 {
1360         HeapTuple       tuple;
1361         ResultRelInfo *resultRelInfo;
1362         Relation        resultRelationDesc;
1363         ItemPointerData ctid;
1364         int                     result;
1365         int                     numIndices;
1366
1367         /*
1368          * abort the operation if not running transactions
1369          */
1370         if (IsBootstrapProcessingMode())
1371         {
1372                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1373                 return;
1374         }
1375
1376         /*
1377          * get the heap tuple out of the tuple table slot
1378          */
1379         tuple = slot->val;
1380
1381         /*
1382          * get information on the (current) result relation
1383          */
1384         resultRelInfo = estate->es_result_relation_info;
1385         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1386
1387         /* BEFORE ROW UPDATE Triggers */
1388         if (resultRelInfo->ri_TrigDesc &&
1389           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1390         {
1391                 HeapTuple       newtuple;
1392
1393                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1394                                                                                 tupleid, tuple);
1395
1396                 if (newtuple == NULL)   /* "do nothing" */
1397                         return;
1398
1399                 if (newtuple != tuple)  /* modified by Trigger(s) */
1400                 {
1401                         /*
1402                          * Insert modified tuple into tuple table slot, replacing the
1403                          * original.  We assume that it was allocated in per-tuple
1404                          * memory context, and therefore will go away by itself. The
1405                          * tuple table slot should not try to clear it.
1406                          */
1407                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1408                         tuple = newtuple;
1409                 }
1410         }
1411
1412         /*
1413          * Check the constraints of the tuple
1414          *
1415          * If we generate a new candidate tuple after EvalPlanQual testing, we
1416          * must loop back here and recheck constraints.  (We don't need to
1417          * redo triggers, however.      If there are any BEFORE triggers then
1418          * trigger.c will have done mark4update to lock the correct tuple, so
1419          * there's no need to do them again.)
1420          */
1421 lreplace:;
1422         if (resultRelationDesc->rd_att->constr)
1423                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1424
1425         /*
1426          * replace the heap tuple
1427          */
1428         result = heap_update(resultRelationDesc, tupleid, tuple,
1429                                                  &ctid,
1430                                                  estate->es_snapshot->curcid);
1431         switch (result)
1432         {
1433                 case HeapTupleSelfUpdated:
1434                         /* already deleted by self; nothing to do */
1435                         return;
1436
1437                 case HeapTupleMayBeUpdated:
1438                         break;
1439
1440                 case HeapTupleUpdated:
1441                         if (XactIsoLevel == XACT_SERIALIZABLE)
1442                                 elog(ERROR, "Can't serialize access due to concurrent update");
1443                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1444                         {
1445                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1446                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1447
1448                                 if (!TupIsNull(epqslot))
1449                                 {
1450                                         *tupleid = ctid;
1451                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1452                                         slot = ExecStoreTuple(tuple,
1453                                                                         estate->es_junkFilter->jf_resultSlot,
1454                                                                                   InvalidBuffer, true);
1455                                         goto lreplace;
1456                                 }
1457                         }
1458                         /* tuple already deleted; nothing to do */
1459                         return;
1460
1461                 default:
1462                         elog(ERROR, "Unknown status %u from heap_update", result);
1463                         return;
1464         }
1465
1466         IncrReplaced();
1467         (estate->es_processed)++;
1468
1469         /*
1470          * Note: instead of having to update the old index tuples associated
1471          * with the heap tuple, all we do is form and insert new index tuples.
1472          * This is because UPDATEs are actually DELETEs and INSERTs and index
1473          * tuple deletion is done automagically by the vacuum daemon. All we
1474          * do is insert new index tuples.  -cim 9/27/89
1475          */
1476
1477         /*
1478          * process indices
1479          *
1480          * heap_update updates a tuple in the base relation by invalidating it
1481          * and then inserting a new tuple to the relation.      As a side effect,
1482          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1483          * field.  So we now insert index tuples using the new tupleid stored
1484          * there.
1485          */
1486
1487         numIndices = resultRelInfo->ri_NumIndices;
1488         if (numIndices > 0)
1489                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1490
1491         /* AFTER ROW UPDATE Triggers */
1492         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1493 }
1494
1495 static char *
1496 ExecRelCheck(ResultRelInfo *resultRelInfo,
1497                          TupleTableSlot *slot, EState *estate)
1498 {
1499         Relation        rel = resultRelInfo->ri_RelationDesc;
1500         int                     ncheck = rel->rd_att->constr->num_check;
1501         ConstrCheck *check = rel->rd_att->constr->check;
1502         ExprContext *econtext;
1503         MemoryContext oldContext;
1504         List       *qual;
1505         int                     i;
1506
1507         /*
1508          * If first time through for this result relation, build expression
1509          * nodetrees for rel's constraint expressions.  Keep them in the
1510          * per-query memory context so they'll survive throughout the query.
1511          */
1512         if (resultRelInfo->ri_ConstraintExprs == NULL)
1513         {
1514                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1515                 resultRelInfo->ri_ConstraintExprs =
1516                         (List **) palloc(ncheck * sizeof(List *));
1517                 for (i = 0; i < ncheck; i++)
1518                 {
1519                         qual = (List *) stringToNode(check[i].ccbin);
1520                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1521                                 ExecPrepareExpr((Expr *) qual, estate);
1522                 }
1523                 MemoryContextSwitchTo(oldContext);
1524         }
1525
1526         /*
1527          * We will use the EState's per-tuple context for evaluating
1528          * constraint expressions (creating it if it's not already there).
1529          */
1530         econtext = GetPerTupleExprContext(estate);
1531
1532         /* Arrange for econtext's scan tuple to be the tuple under test */
1533         econtext->ecxt_scantuple = slot;
1534
1535         /* And evaluate the constraints */
1536         for (i = 0; i < ncheck; i++)
1537         {
1538                 qual = resultRelInfo->ri_ConstraintExprs[i];
1539
1540                 /*
1541                  * NOTE: SQL92 specifies that a NULL result from a constraint
1542                  * expression is not to be treated as a failure.  Therefore, tell
1543                  * ExecQual to return TRUE for NULL.
1544                  */
1545                 if (!ExecQual(qual, econtext, true))
1546                         return check[i].ccname;
1547         }
1548
1549         /* NULL result means no error */
1550         return (char *) NULL;
1551 }
1552
1553 void
1554 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1555                                 TupleTableSlot *slot, EState *estate)
1556 {
1557         Relation        rel = resultRelInfo->ri_RelationDesc;
1558         HeapTuple       tuple = slot->val;
1559         TupleConstr *constr = rel->rd_att->constr;
1560
1561         Assert(constr);
1562
1563         if (constr->has_not_null)
1564         {
1565                 int                     natts = rel->rd_att->natts;
1566                 int                     attrChk;
1567
1568                 for (attrChk = 1; attrChk <= natts; attrChk++)
1569                 {
1570                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1571                                 heap_attisnull(tuple, attrChk))
1572                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1573                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1574                 }
1575         }
1576
1577         if (constr->num_check > 0)
1578         {
1579                 char       *failed;
1580
1581                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1582                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1583                                  caller, failed, RelationGetRelationName(rel));
1584         }
1585 }
1586
1587 /*
1588  * Check a modified tuple to see if we want to process its updated version
1589  * under READ COMMITTED rules.
1590  *
1591  * See backend/executor/README for some info about how this works.
1592  */
1593 TupleTableSlot *
1594 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1595 {
1596         evalPlanQual *epq;
1597         EState     *epqstate;
1598         Relation        relation;
1599         HeapTupleData tuple;
1600         HeapTuple       copyTuple = NULL;
1601         bool            endNode;
1602
1603         Assert(rti != 0);
1604
1605         /*
1606          * find relation containing target tuple
1607          */
1608         if (estate->es_result_relation_info != NULL &&
1609                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1610                 relation = estate->es_result_relation_info->ri_RelationDesc;
1611         else
1612         {
1613                 List       *l;
1614
1615                 relation = NULL;
1616                 foreach(l, estate->es_rowMark)
1617                 {
1618                         if (((execRowMark *) lfirst(l))->rti == rti)
1619                         {
1620                                 relation = ((execRowMark *) lfirst(l))->relation;
1621                                 break;
1622                         }
1623                 }
1624                 if (relation == NULL)
1625                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1626         }
1627
1628         /*
1629          * fetch tid tuple
1630          *
1631          * Loop here to deal with updated or busy tuples
1632          */
1633         tuple.t_self = *tid;
1634         for (;;)
1635         {
1636                 Buffer          buffer;
1637
1638                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1639                 {
1640                         TransactionId xwait = SnapshotDirty->xmax;
1641
1642                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1643                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1644
1645                         /*
1646                          * If tuple is being updated by other transaction then we have
1647                          * to wait for its commit/abort.
1648                          */
1649                         if (TransactionIdIsValid(xwait))
1650                         {
1651                                 ReleaseBuffer(buffer);
1652                                 XactLockTableWait(xwait);
1653                                 continue;
1654                         }
1655
1656                         /*
1657                          * We got tuple - now copy it for use by recheck query.
1658                          */
1659                         copyTuple = heap_copytuple(&tuple);
1660                         ReleaseBuffer(buffer);
1661                         break;
1662                 }
1663
1664                 /*
1665                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1666                  * Note that it's possible to get invalid SnapshotDirty->tid if
1667                  * tuple updated by this transaction. Have we to check this ?
1668                  */
1669                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1670                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1671                 {
1672                         /* updated, so look at the updated copy */
1673                         tuple.t_self = SnapshotDirty->tid;
1674                         continue;
1675                 }
1676
1677                 /*
1678                  * Deleted or updated by this transaction; forget it.
1679                  */
1680                 return NULL;
1681         }
1682
1683         /*
1684          * For UPDATE/DELETE we have to return tid of actual row we're
1685          * executing PQ for.
1686          */
1687         *tid = tuple.t_self;
1688
1689         /*
1690          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1691          */
1692         epq = estate->es_evalPlanQual;
1693         endNode = true;
1694
1695         if (epq != NULL && epq->rti == 0)
1696         {
1697                 /* Top PQ stack entry is idle, so re-use it */
1698                 Assert(!(estate->es_useEvalPlan) && epq->next == NULL);
1699                 epq->rti = rti;
1700                 endNode = false;
1701         }
1702
1703         /*
1704          * If this is request for another RTE - Ra, - then we have to check
1705          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1706          * updated again and we have to re-start old execution for Ra and
1707          * forget all what we done after Ra was suspended. Cool? -:))
1708          */
1709         if (epq != NULL && epq->rti != rti &&
1710                 epq->estate->es_evTuple[rti - 1] != NULL)
1711         {
1712                 do
1713                 {
1714                         evalPlanQual *oldepq;
1715
1716                         /* stop execution */
1717                         EvalPlanQualStop(epq);
1718                         /* pop previous PlanQual from the stack */
1719                         oldepq = epq->next;
1720                         Assert(oldepq && oldepq->rti != 0);
1721                         /* push current PQ to freePQ stack */
1722                         oldepq->free = epq;
1723                         epq = oldepq;
1724                         estate->es_evalPlanQual = epq;
1725                 } while (epq->rti != rti);
1726         }
1727
1728         /*
1729          * If we are requested for another RTE then we have to suspend
1730          * execution of current PlanQual and start execution for new one.
1731          */
1732         if (epq == NULL || epq->rti != rti)
1733         {
1734                 /* try to reuse plan used previously */
1735                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1736
1737                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1738                 {
1739                         newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual));
1740                         newepq->free = NULL;
1741                         newepq->estate = NULL;
1742                         newepq->planstate = NULL;
1743                 }
1744                 else
1745                 {
1746                         /* recycle previously used PlanQual */
1747                         Assert(newepq->estate == NULL);
1748                         epq->free = NULL;
1749                 }
1750                 /* push current PQ to the stack */
1751                 newepq->next = epq;
1752                 epq = newepq;
1753                 estate->es_evalPlanQual = epq;
1754                 epq->rti = rti;
1755                 endNode = false;
1756         }
1757
1758         Assert(epq->rti == rti);
1759
1760         /*
1761          * Ok - we're requested for the same RTE.  Unfortunately we still have
1762          * to end and restart execution of the plan, because ExecReScan
1763          * wouldn't ensure that upper plan nodes would reset themselves.  We
1764          * could make that work if insertion of the target tuple were
1765          * integrated with the Param mechanism somehow, so that the upper plan
1766          * nodes know that their children's outputs have changed.
1767          *
1768          * Note that the stack of free evalPlanQual nodes is quite useless at
1769          * the moment, since it only saves us from pallocing/releasing the
1770          * evalPlanQual nodes themselves.  But it will be useful once we
1771          * implement ReScan instead of end/restart for re-using PlanQual nodes.
1772          */
1773         if (endNode)
1774         {
1775                 /* stop execution */
1776                 EvalPlanQualStop(epq);
1777         }
1778
1779         /*
1780          * Initialize new recheck query.
1781          *
1782          * Note: if we were re-using PlanQual plans via ExecReScan, we'd need
1783          * to instead copy down changeable state from the top plan (including
1784          * es_result_relation_info, es_junkFilter) and reset locally changeable
1785          * state in the epq (including es_param_exec_vals, es_evTupleNull).
1786          */
1787         EvalPlanQualStart(epq, estate, epq->next);
1788
1789         /*
1790          * free old RTE' tuple, if any, and store target tuple where
1791          * relation's scan node will see it
1792          */
1793         epqstate = epq->estate;
1794         if (epqstate->es_evTuple[rti - 1] != NULL)
1795                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1796         epqstate->es_evTuple[rti - 1] = copyTuple;
1797
1798         return EvalPlanQualNext(estate);
1799 }
1800
1801 static TupleTableSlot *
1802 EvalPlanQualNext(EState *estate)
1803 {
1804         evalPlanQual *epq = estate->es_evalPlanQual;
1805         MemoryContext oldcontext;
1806         TupleTableSlot *slot;
1807
1808         Assert(epq->rti != 0);
1809
1810 lpqnext:;
1811         oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt);
1812         slot = ExecProcNode(epq->planstate);
1813         MemoryContextSwitchTo(oldcontext);
1814
1815         /*
1816          * No more tuples for this PQ. Continue previous one.
1817          */
1818         if (TupIsNull(slot))
1819         {
1820                 evalPlanQual *oldepq;
1821
1822                 /* stop execution */
1823                 EvalPlanQualStop(epq);
1824                 /* pop old PQ from the stack */
1825                 oldepq = epq->next;
1826                 if (oldepq == NULL)
1827                 {
1828                         /* this is the first (oldest) PQ - mark as free */
1829                         epq->rti = 0;
1830                         estate->es_useEvalPlan = false;
1831                         /* and continue Query execution */
1832                         return (NULL);
1833                 }
1834                 Assert(oldepq->rti != 0);
1835                 /* push current PQ to freePQ stack */
1836                 oldepq->free = epq;
1837                 epq = oldepq;
1838                 estate->es_evalPlanQual = epq;
1839                 goto lpqnext;
1840         }
1841
1842         return (slot);
1843 }
1844
1845 static void
1846 EndEvalPlanQual(EState *estate)
1847 {
1848         evalPlanQual *epq = estate->es_evalPlanQual;
1849
1850         if (epq->rti == 0)                      /* plans already shutdowned */
1851         {
1852                 Assert(epq->next == NULL);
1853                 return;
1854         }
1855
1856         for (;;)
1857         {
1858                 evalPlanQual *oldepq;
1859
1860                 /* stop execution */
1861                 EvalPlanQualStop(epq);
1862                 /* pop old PQ from the stack */
1863                 oldepq = epq->next;
1864                 if (oldepq == NULL)
1865                 {
1866                         /* this is the first (oldest) PQ - mark as free */
1867                         epq->rti = 0;
1868                         estate->es_useEvalPlan = false;
1869                         break;
1870                 }
1871                 Assert(oldepq->rti != 0);
1872                 /* push current PQ to freePQ stack */
1873                 oldepq->free = epq;
1874                 epq = oldepq;
1875                 estate->es_evalPlanQual = epq;
1876         }
1877 }
1878
1879 /*
1880  * Start execution of one level of PlanQual.
1881  *
1882  * This is a cut-down version of ExecutorStart(): we copy some state from
1883  * the top-level estate rather than initializing it fresh.
1884  */
1885 static void
1886 EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
1887 {
1888         EState     *epqstate;
1889         int                     rtsize;
1890         MemoryContext oldcontext;
1891
1892         rtsize = length(estate->es_range_table);
1893
1894         epq->estate = epqstate = CreateExecutorState();
1895
1896         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1897
1898         /*
1899          * The epqstates share the top query's copy of unchanging state such
1900          * as the snapshot, rangetable, result-rel info, and external Param info.
1901          * They need their own copies of local state, including a tuple table,
1902          * es_param_exec_vals, etc.
1903          */
1904         epqstate->es_direction = ForwardScanDirection;
1905         epqstate->es_snapshot = estate->es_snapshot;
1906         epqstate->es_range_table = estate->es_range_table;
1907         epqstate->es_result_relations = estate->es_result_relations;
1908         epqstate->es_num_result_relations = estate->es_num_result_relations;
1909         epqstate->es_result_relation_info = estate->es_result_relation_info;
1910         epqstate->es_junkFilter = estate->es_junkFilter;
1911         epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor;
1912         epqstate->es_param_list_info = estate->es_param_list_info;
1913         if (estate->es_topPlan->nParamExec > 0)
1914                 epqstate->es_param_exec_vals = (ParamExecData *)
1915                         palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
1916         epqstate->es_rowMark = estate->es_rowMark;
1917         epqstate->es_instrument = estate->es_instrument;
1918         epqstate->es_topPlan = estate->es_topPlan;
1919         /*
1920          * Each epqstate must have its own es_evTupleNull state, but
1921          * all the stack entries share es_evTuple state.  This allows
1922          * sub-rechecks to inherit the value being examined by an
1923          * outer recheck.
1924          */
1925         epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool));
1926         if (priorepq == NULL)
1927                 /* first PQ stack entry */
1928                 epqstate->es_evTuple = (HeapTuple *)
1929                         palloc0(rtsize * sizeof(HeapTuple));
1930         else
1931                 /* later stack entries share the same storage */
1932                 epqstate->es_evTuple = priorepq->estate->es_evTuple;
1933
1934         epqstate->es_tupleTable =
1935                 ExecCreateTupleTable(estate->es_tupleTable->size);
1936
1937         epq->planstate = ExecInitNode(estate->es_topPlan, epqstate);
1938
1939         MemoryContextSwitchTo(oldcontext);
1940 }
1941
1942 /*
1943  * End execution of one level of PlanQual.
1944  *
1945  * This is a cut-down version of ExecutorEnd(); basically we want to do most
1946  * of the normal cleanup, but *not* close result relations (which we are
1947  * just sharing from the outer query).
1948  */
1949 static void
1950 EvalPlanQualStop(evalPlanQual *epq)
1951 {
1952         EState     *epqstate = epq->estate;
1953         MemoryContext oldcontext;
1954
1955         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1956
1957         ExecEndNode(epq->planstate);
1958
1959         ExecDropTupleTable(epqstate->es_tupleTable, true);
1960         epqstate->es_tupleTable = NULL;
1961
1962         if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1963         {
1964                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1965                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1966         }
1967
1968         MemoryContextSwitchTo(oldcontext);
1969
1970         FreeExecutorState(epqstate);
1971
1972         epq->estate = NULL;
1973         epq->planstate = NULL;
1974 }