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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.194 2002/12/15 21:01:34 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 /* decls for local routines only used within this module */
  50 static void InitPlan(QueryDesc *queryDesc);
  51 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  52                                   Index resultRelationIndex,
  53                                   List *rangeTable,
  54                                   CmdType operation);
  55 static TupleTableSlot *ExecutePlan(EState *estate, PlanState *planstate,
  56                         CmdType operation,
  57                         long numberTuples,
  58                         ScanDirection direction,
  59                         DestReceiver *destfunc);
  60 static void ExecSelect(TupleTableSlot *slot,
  61                    DestReceiver *destfunc,
  62                    EState *estate);
  63 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  64                    EState *estate);
  65 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  66                    EState *estate);
  67 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  68                    EState *estate);
  69 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  70 static void EndEvalPlanQual(EState *estate);
  71 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  72
  73 /* end of local decls */
  74
  75
  76 /* ----------------------------------------------------------------
  77  *              ExecutorStart
  78  *
  79  *              This routine must be called at the beginning of any execution of any
  80  *              query plan
  81  *
  82  * Takes a QueryDesc previously created by CreateQueryDesc (it's not real
  83  * clear why we bother to separate the two functions, but...).  The tupDesc
  84  * field of the QueryDesc is filled in to describe the tuples that will be
  85  * returned, and the internal fields (estate and planstate) are set up.
  86  *
  87  * NB: the CurrentMemoryContext when this is called will become the parent
  88  * of the per-query context used for this Executor invocation.
  89  * ----------------------------------------------------------------
  90  */
  91 void
  92 ExecutorStart(QueryDesc *queryDesc)
  93 {
  94         EState     *estate;
  95         MemoryContext oldcontext;
  96
  97         /* sanity checks: queryDesc must not be started already */
  98         Assert(queryDesc != NULL);
  99         Assert(queryDesc->estate == NULL);
 100
 101         /*
 102          * Build EState, switch into per-query memory context for startup.
 103          */
 104         estate = CreateExecutorState();
 105         queryDesc->estate = estate;
 106
 107         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 108
 109         /*
 110          * Fill in parameters, if any, from queryDesc
 111          */
 112         estate->es_param_list_info = queryDesc->params;
 113
 114         if (queryDesc->plantree->nParamExec > 0)
 115                 estate->es_param_exec_vals = (ParamExecData *)
 116                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 117
 118         estate->es_instrument = queryDesc->doInstrument;
 119
 120         /*
 121          * Make our own private copy of the current query snapshot data.
 122          *
 123          * This "freezes" our idea of which tuples are good and which are not for
 124          * the life of this query, even if it outlives the current command and
 125          * current snapshot.
 126          */
 127         estate->es_snapshot = CopyQuerySnapshot();
 128
 129         /*
 130          * Initialize the plan state tree
 131          */
 132         InitPlan(queryDesc);
 133
 134         MemoryContextSwitchTo(oldcontext);
 135 }
 136
 137 /* ----------------------------------------------------------------
 138  *              ExecutorRun
 139  *
 140  *              This is the main routine of the executor module. It accepts
 141  *              the query descriptor from the traffic cop and executes the
 142  *              query plan.
 143  *
 144  *              ExecutorStart must have been called already.
 145  *
 146  *              If direction is NoMovementScanDirection then nothing is done
 147  *              except to start up/shut down the destination.  Otherwise,
 148  *              we retrieve up to 'count' tuples in the specified direction.
 149  *
 150  *              Note: count = 0 is interpreted as no portal limit, e.g. run to
 151  *              completion.
 152  *
 153  * ----------------------------------------------------------------
 154  */
 155 TupleTableSlot *
 156 ExecutorRun(QueryDesc *queryDesc,
 157                         ScanDirection direction, long count)
 158 {
 159         EState     *estate;
 160         CmdType         operation;
 161         CommandDest dest;
 162         DestReceiver *destfunc;
 163         TupleTableSlot *result;
 164         MemoryContext oldcontext;
 165
 166         /* sanity checks */
 167         Assert(queryDesc != NULL);
 168
 169         estate = queryDesc->estate;
 170
 171         Assert(estate != NULL);
 172
 173         /*
 174          * Switch into per-query memory context
 175          */
 176         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 177
 178         /*
 179          * extract information from the query descriptor and the query
 180          * feature.
 181          */
 182         operation = queryDesc->operation;
 183         dest = queryDesc->dest;
 184
 185         /*
 186          * startup tuple receiver
 187          */
 188         estate->es_processed = 0;
 189         estate->es_lastoid = InvalidOid;
 190
 191         destfunc = DestToFunction(dest);
 192         (*destfunc->setup) (destfunc, (int) operation,
 193                                                 queryDesc->portalName, queryDesc->tupDesc);
 194
 195         /*
 196          * run plan
 197          */
 198         if (direction == NoMovementScanDirection)
 199                 result = NULL;
 200         else
 201                 result = ExecutePlan(estate,
 202                                                          queryDesc->planstate,
 203                                                          operation,
 204                                                          count,
 205                                                          direction,
 206                                                          destfunc);
 207
 208         /*
 209          * shutdown receiver
 210          */
 211         (*destfunc->cleanup) (destfunc);
 212
 213         MemoryContextSwitchTo(oldcontext);
 214
 215         return result;
 216 }
 217
 218 /* ----------------------------------------------------------------
 219  *              ExecutorEnd
 220  *
 221  *              This routine must be called at the end of execution of any
 222  *              query plan
 223  * ----------------------------------------------------------------
 224  */
 225 void
 226 ExecutorEnd(QueryDesc *queryDesc)
 227 {
 228         EState     *estate;
 229         MemoryContext oldcontext;
 230
 231         /* sanity checks */
 232         Assert(queryDesc != NULL);
 233
 234         estate = queryDesc->estate;
 235
 236         Assert(estate != NULL);
 237
 238         /*
 239          * Switch into per-query memory context to run ExecEndPlan
 240          */
 241         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 242
 243         ExecEndPlan(queryDesc->planstate, estate);
 244
 245         /*
 246          * Must switch out of context before destroying it
 247          */
 248         MemoryContextSwitchTo(oldcontext);
 249
 250         /*
 251          * Release EState and per-query memory context.  This should release
 252          * everything the executor has allocated.
 253          */
 254         FreeExecutorState(estate);
 255
 256         /* Reset queryDesc fields that no longer point to anything */
 257         queryDesc->tupDesc = NULL;
 258         queryDesc->estate = NULL;
 259         queryDesc->planstate = NULL;
 260 }
 261
 262
 263 /*
 264  * ExecCheckRTPerms
 265  *              Check access permissions for all relations listed in a range table.
 266  */
 267 void
 268 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 269 {
 270         List       *lp;
 271
 272         foreach(lp, rangeTable)
 273         {
 274                 RangeTblEntry *rte = lfirst(lp);
 275
 276                 ExecCheckRTEPerms(rte, operation);
 277         }
 278 }
 279
 280 /*
 281  * ExecCheckRTEPerms
 282  *              Check access permissions for a single RTE.
 283  */
 284 static void
 285 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 286 {
 287         Oid                     relOid;
 288         AclId           userid;
 289         AclResult       aclcheck_result;
 290
 291         /*
 292          * If it's a subquery, recursively examine its rangetable.
 293          */
 294         if (rte->rtekind == RTE_SUBQUERY)
 295         {
 296                 ExecCheckRTPerms(rte->subquery->rtable, operation);
 297                 return;
 298         }
 299
 300         /*
 301          * Otherwise, only plain-relation RTEs need to be checked here.
 302          * Function RTEs are checked by init_fcache when the function is prepared
 303          * for execution. Join and special RTEs need no checks.
 304          */
 305         if (rte->rtekind != RTE_RELATION)
 306                 return;
 307
 308         relOid = rte->relid;
 309
 310         /*
 311          * userid to check as: current user unless we have a setuid
 312          * indication.
 313          *
 314          * Note: GetUserId() is presently fast enough that there's no harm in
 315          * calling it separately for each RTE.  If that stops being true, we
 316          * could call it once in ExecCheckRTPerms and pass the userid down
 317          * from there.  But for now, no need for the extra clutter.
 318          */
 319         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 320
 321 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 322
 323         if (rte->checkForRead)
 324         {
 325                 aclcheck_result = CHECK(ACL_SELECT);
 326                 if (aclcheck_result != ACLCHECK_OK)
 327                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 328         }
 329
 330         if (rte->checkForWrite)
 331         {
 332                 /*
 333                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 334                  * Right now we don't distinguish that from true update as far as
 335                  * permissions checks are concerned.
 336                  */
 337                 switch (operation)
 338                 {
 339                         case CMD_INSERT:
 340                                 aclcheck_result = CHECK(ACL_INSERT);
 341                                 break;
 342                         case CMD_SELECT:
 343                         case CMD_UPDATE:
 344                                 aclcheck_result = CHECK(ACL_UPDATE);
 345                                 break;
 346                         case CMD_DELETE:
 347                                 aclcheck_result = CHECK(ACL_DELETE);
 348                                 break;
 349                         default:
 350                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 351                                          operation);
 352                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 353                                 break;
 354                 }
 355                 if (aclcheck_result != ACLCHECK_OK)
 356                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 357         }
 358 }
 359
 360
 361 /* ===============================================================
 362  * ===============================================================
 363                                                  static routines follow
 364  * ===============================================================
 365  * ===============================================================
 366  */
 367
 368 typedef struct execRowMark
 369 {
 370         Relation        relation;
 371         Index           rti;
 372         char            resname[32];
 373 } execRowMark;
 374
 375 typedef struct evalPlanQual
 376 {
 377         Plan       *plan;                       /* XXX temporary */
 378         PlanState  *planstate;
 379         Index           rti;
 380         EState          estate;
 381         struct evalPlanQual *free;
 382 } evalPlanQual;
 383
 384 /* ----------------------------------------------------------------
 385  *              InitPlan
 386  *
 387  *              Initializes the query plan: open files, allocate storage
 388  *              and start up the rule manager
 389  * ----------------------------------------------------------------
 390  */
 391 static void
 392 InitPlan(QueryDesc *queryDesc)
 393 {
 394         CmdType         operation = queryDesc->operation;
 395         Query *parseTree = queryDesc->parsetree;
 396         Plan *plan = queryDesc->plantree;
 397         EState *estate = queryDesc->estate;
 398         PlanState  *planstate;
 399         List       *rangeTable;
 400         Relation        intoRelationDesc;
 401         TupleDesc       tupType;
 402
 403         /*
 404          * Do permissions checks.  It's sufficient to examine the query's
 405          * top rangetable here --- subplan RTEs will be checked during
 406          * ExecInitSubPlan().
 407          */
 408         ExecCheckRTPerms(parseTree->rtable, operation);
 409
 410         /*
 411          * get information from query descriptor
 412          */
 413         rangeTable = parseTree->rtable;
 414
 415         /*
 416          * initialize the node's execution state
 417          */
 418         estate->es_range_table = rangeTable;
 419
 420         /*
 421          * if there is a result relation, initialize result relation stuff
 422          */
 423         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 424         {
 425                 List       *resultRelations = parseTree->resultRelations;
 426                 int                     numResultRelations;
 427                 ResultRelInfo *resultRelInfos;
 428
 429                 if (resultRelations != NIL)
 430                 {
 431                         /*
 432                          * Multiple result relations (due to inheritance)
 433                          * parseTree->resultRelations identifies them all
 434                          */
 435                         ResultRelInfo *resultRelInfo;
 436
 437                         numResultRelations = length(resultRelations);
 438                         resultRelInfos = (ResultRelInfo *)
 439                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 440                         resultRelInfo = resultRelInfos;
 441                         while (resultRelations != NIL)
 442                         {
 443                                 initResultRelInfo(resultRelInfo,
 444                                                                   lfirsti(resultRelations),
 445                                                                   rangeTable,
 446                                                                   operation);
 447                                 resultRelInfo++;
 448                                 resultRelations = lnext(resultRelations);
 449                         }
 450                 }
 451                 else
 452                 {
 453                         /*
 454                          * Single result relation identified by
 455                          * parseTree->resultRelation
 456                          */
 457                         numResultRelations = 1;
 458                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 459                         initResultRelInfo(resultRelInfos,
 460                                                           parseTree->resultRelation,
 461                                                           rangeTable,
 462                                                           operation);
 463                 }
 464
 465                 estate->es_result_relations = resultRelInfos;
 466                 estate->es_num_result_relations = numResultRelations;
 467                 /* Initialize to first or only result rel */
 468                 estate->es_result_relation_info = resultRelInfos;
 469         }
 470         else
 471         {
 472                 /*
 473                  * if no result relation, then set state appropriately
 474                  */
 475                 estate->es_result_relations = NULL;
 476                 estate->es_num_result_relations = 0;
 477                 estate->es_result_relation_info = NULL;
 478         }
 479
 480         /*
 481          * Have to lock relations selected for update
 482          */
 483         estate->es_rowMark = NIL;
 484         if (parseTree->rowMarks != NIL)
 485         {
 486                 List       *l;
 487
 488                 foreach(l, parseTree->rowMarks)
 489                 {
 490                         Index           rti = lfirsti(l);
 491                         Oid                     relid = getrelid(rti, rangeTable);
 492                         Relation        relation;
 493                         execRowMark *erm;
 494
 495                         relation = heap_open(relid, RowShareLock);
 496                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 497                         erm->relation = relation;
 498                         erm->rti = rti;
 499                         snprintf(erm->resname, 32, "ctid%u", rti);
 500                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 501                 }
 502         }
 503
 504         /*
 505          * initialize the executor "tuple" table.  We need slots for all the
 506          * plan nodes, plus possibly output slots for the junkfilter(s). At
 507          * this point we aren't sure if we need junkfilters, so just add slots
 508          * for them unconditionally.
 509          */
 510         {
 511                 int                     nSlots = ExecCountSlotsNode(plan);
 512
 513                 if (parseTree->resultRelations != NIL)
 514                         nSlots += length(parseTree->resultRelations);
 515                 else
 516                         nSlots += 1;
 517                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 518         }
 519
 520         /* mark EvalPlanQual not active */
 521         estate->es_origPlan = plan;
 522         estate->es_evalPlanQual = NULL;
 523         estate->es_evTuple = NULL;
 524         estate->es_evTupleNull = NULL;
 525         estate->es_useEvalPlan = false;
 526
 527         /*
 528          * initialize the private state information for all the nodes in the
 529          * query tree.  This opens files, allocates storage and leaves us
 530          * ready to start processing tuples.
 531          */
 532         planstate = ExecInitNode(plan, estate);
 533
 534         /*
 535          * Get the tuple descriptor describing the type of tuples to return.
 536          * (this is especially important if we are creating a relation with
 537          * "SELECT INTO")
 538          */
 539         tupType = ExecGetTupType(planstate);
 540
 541         /*
 542          * Initialize the junk filter if needed. SELECT and INSERT queries
 543          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 544          * DELETE always need one, since there's always a junk 'ctid'
 545          * attribute present --- no need to look first.
 546          */
 547         {
 548                 bool            junk_filter_needed = false;
 549                 List       *tlist;
 550
 551                 switch (operation)
 552                 {
 553                         case CMD_SELECT:
 554                         case CMD_INSERT:
 555                                 foreach(tlist, plan->targetlist)
 556                                 {
 557                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 558
 559                                         if (tle->resdom->resjunk)
 560                                         {
 561                                                 junk_filter_needed = true;
 562                                                 break;
 563                                         }
 564                                 }
 565                                 break;
 566                         case CMD_UPDATE:
 567                         case CMD_DELETE:
 568                                 junk_filter_needed = true;
 569                                 break;
 570                         default:
 571                                 break;
 572                 }
 573
 574                 if (junk_filter_needed)
 575                 {
 576                         /*
 577                          * If there are multiple result relations, each one needs its
 578                          * own junk filter.  Note this is only possible for
 579                          * UPDATE/DELETE, so we can't be fooled by some needing a
 580                          * filter and some not.
 581                          */
 582                         if (parseTree->resultRelations != NIL)
 583                         {
 584                                 PlanState **appendplans;
 585                                 int                     as_nplans;
 586                                 ResultRelInfo *resultRelInfo;
 587                                 int                     i;
 588
 589                                 /* Top plan had better be an Append here. */
 590                                 Assert(IsA(plan, Append));
 591                                 Assert(((Append *) plan)->isTarget);
 592                                 Assert(IsA(planstate, AppendState));
 593                                 appendplans = ((AppendState *) planstate)->appendplans;
 594                                 as_nplans = ((AppendState *) planstate)->as_nplans;
 595                                 Assert(as_nplans == estate->es_num_result_relations);
 596                                 resultRelInfo = estate->es_result_relations;
 597                                 for (i = 0; i < as_nplans; i++)
 598                                 {
 599                                         PlanState  *subplan = appendplans[i];
 600                                         JunkFilter *j;
 601
 602                                         j = ExecInitJunkFilter(subplan->plan->targetlist,
 603                                                                                    ExecGetTupType(subplan),
 604                                                           ExecAllocTableSlot(estate->es_tupleTable));
 605                                         resultRelInfo->ri_junkFilter = j;
 606                                         resultRelInfo++;
 607                                 }
 608
 609                                 /*
 610                                  * Set active junkfilter too; at this point ExecInitAppend
 611                                  * has already selected an active result relation...
 612                                  */
 613                                 estate->es_junkFilter =
 614                                         estate->es_result_relation_info->ri_junkFilter;
 615                         }
 616                         else
 617                         {
 618                                 /* Normal case with just one JunkFilter */
 619                                 JunkFilter *j;
 620
 621                                 j = ExecInitJunkFilter(planstate->plan->targetlist,
 622                                                                            tupType,
 623                                                           ExecAllocTableSlot(estate->es_tupleTable));
 624                                 estate->es_junkFilter = j;
 625                                 if (estate->es_result_relation_info)
 626                                         estate->es_result_relation_info->ri_junkFilter = j;
 627
 628                                 /* For SELECT, want to return the cleaned tuple type */
 629                                 if (operation == CMD_SELECT)
 630                                         tupType = j->jf_cleanTupType;
 631                         }
 632                 }
 633                 else
 634                         estate->es_junkFilter = NULL;
 635         }
 636
 637         /*
 638          * initialize the "into" relation
 639          */
 640         intoRelationDesc = (Relation) NULL;
 641
 642         if (operation == CMD_SELECT)
 643         {
 644                 if (!parseTree->isPortal)
 645                 {
 646                         /*
 647                          * a select into table --- need to create the "into" table
 648                          */
 649                         if (parseTree->into != NULL)
 650                         {
 651                                 char       *intoName;
 652                                 Oid                     namespaceId;
 653                                 AclResult       aclresult;
 654                                 Oid                     intoRelationId;
 655                                 TupleDesc       tupdesc;
 656
 657                                 /*
 658                                  * find namespace to create in, check permissions
 659                                  */
 660                                 intoName = parseTree->into->relname;
 661                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 662
 663                                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 664                                                                                                   ACL_CREATE);
 665                                 if (aclresult != ACLCHECK_OK)
 666                                         aclcheck_error(aclresult,
 667                                                                    get_namespace_name(namespaceId));
 668
 669                                 /*
 670                                  * have to copy tupType to get rid of constraints
 671                                  */
 672                                 tupdesc = CreateTupleDescCopy(tupType);
 673
 674                                 /*
 675                                  * Formerly we forced the output table to have OIDs, but
 676                                  * as of 7.3 it will not have OIDs, because it's too late
 677                                  * here to change the tupdescs of the already-initialized
 678                                  * plan tree.  (Perhaps we could recurse and change them
 679                                  * all, but it's not really worth the trouble IMHO...)
 680                                  */
 681
 682                                 intoRelationId =
 683                                         heap_create_with_catalog(intoName,
 684                                                                                          namespaceId,
 685                                                                                          tupdesc,
 686                                                                                          RELKIND_RELATION,
 687                                                                                          false,
 688                                                                                          ONCOMMIT_NOOP,
 689                                                                                          allowSystemTableMods);
 690
 691                                 FreeTupleDesc(tupdesc);
 692
 693                                 /*
 694                                  * Advance command counter so that the newly-created
 695                                  * relation's catalog tuples will be visible to heap_open.
 696                                  */
 697                                 CommandCounterIncrement();
 698
 699                                 /*
 700                                  * If necessary, create a TOAST table for the into
 701                                  * relation. Note that AlterTableCreateToastTable ends
 702                                  * with CommandCounterIncrement(), so that the TOAST table
 703                                  * will be visible for insertion.
 704                                  */
 705                                 AlterTableCreateToastTable(intoRelationId, true);
 706
 707                                 intoRelationDesc = heap_open(intoRelationId,
 708                                                                                          AccessExclusiveLock);
 709                         }
 710                 }
 711         }
 712
 713         estate->es_into_relation_descriptor = intoRelationDesc;
 714
 715         queryDesc->tupDesc = tupType;
 716         queryDesc->planstate = planstate;
 717 }
 718
 719 /*
 720  * Initialize ResultRelInfo data for one result relation
 721  */
 722 static void
 723 initResultRelInfo(ResultRelInfo *resultRelInfo,
 724                                   Index resultRelationIndex,
 725                                   List *rangeTable,
 726                                   CmdType operation)
 727 {
 728         Oid                     resultRelationOid;
 729         Relation        resultRelationDesc;
 730
 731         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 732         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 733
 734         switch (resultRelationDesc->rd_rel->relkind)
 735         {
 736                 case RELKIND_SEQUENCE:
 737                         elog(ERROR, "You can't change sequence relation %s",
 738                                  RelationGetRelationName(resultRelationDesc));
 739                         break;
 740                 case RELKIND_TOASTVALUE:
 741                         elog(ERROR, "You can't change toast relation %s",
 742                                  RelationGetRelationName(resultRelationDesc));
 743                         break;
 744                 case RELKIND_VIEW:
 745                         elog(ERROR, "You can't change view relation %s",
 746                                  RelationGetRelationName(resultRelationDesc));
 747                         break;
 748         }
 749
 750         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 751         resultRelInfo->type = T_ResultRelInfo;
 752         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 753         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 754         resultRelInfo->ri_NumIndices = 0;
 755         resultRelInfo->ri_IndexRelationDescs = NULL;
 756         resultRelInfo->ri_IndexRelationInfo = NULL;
 757         /* make a copy so as not to depend on relcache info not changing... */
 758         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 759         resultRelInfo->ri_TrigFunctions = NULL;
 760         resultRelInfo->ri_ConstraintExprs = NULL;
 761         resultRelInfo->ri_junkFilter = NULL;
 762
 763         /*
 764          * If there are indices on the result relation, open them and save
 765          * descriptors in the result relation info, so that we can add new
 766          * index entries for the tuples we add/update.  We need not do this
 767          * for a DELETE, however, since deletion doesn't affect indexes.
 768          */
 769         if (resultRelationDesc->rd_rel->relhasindex &&
 770                 operation != CMD_DELETE)
 771                 ExecOpenIndices(resultRelInfo);
 772 }
 773
 774 /* ----------------------------------------------------------------
 775  *              ExecEndPlan
 776  *
 777  *              Cleans up the query plan -- closes files and frees up storage
 778  *
 779  * NOTE: we are no longer very worried about freeing storage per se
 780  * in this code; FreeExecutorState should be guaranteed to release all
 781  * memory that needs to be released.  What we are worried about doing
 782  * is closing relations and dropping buffer pins.  Thus, for example,
 783  * tuple tables must be cleared or dropped to ensure pins are released.
 784  * ----------------------------------------------------------------
 785  */
 786 void
 787 ExecEndPlan(PlanState *planstate, EState *estate)
 788 {
 789         ResultRelInfo *resultRelInfo;
 790         int                     i;
 791         List       *l;
 792
 793         /*
 794          * shut down any PlanQual processing we were doing
 795          */
 796         if (estate->es_evalPlanQual != NULL)
 797                 EndEvalPlanQual(estate);
 798
 799         /*
 800          * shut down the node-type-specific query processing
 801          */
 802         ExecEndNode(planstate);
 803
 804         /*
 805          * destroy the executor "tuple" table.
 806          */
 807         ExecDropTupleTable(estate->es_tupleTable, true);
 808         estate->es_tupleTable = NULL;
 809
 810         /*
 811          * close the result relation(s) if any, but hold locks until xact
 812          * commit.
 813          */
 814         resultRelInfo = estate->es_result_relations;
 815         for (i = estate->es_num_result_relations; i > 0; i--)
 816         {
 817                 /* Close indices and then the relation itself */
 818                 ExecCloseIndices(resultRelInfo);
 819                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 820                 resultRelInfo++;
 821         }
 822
 823         /*
 824          * close the "into" relation if necessary, again keeping lock
 825          */
 826         if (estate->es_into_relation_descriptor != NULL)
 827                 heap_close(estate->es_into_relation_descriptor, NoLock);
 828
 829         /*
 830          * close any relations selected FOR UPDATE, again keeping locks
 831          */
 832         foreach(l, estate->es_rowMark)
 833         {
 834                 execRowMark *erm = lfirst(l);
 835
 836                 heap_close(erm->relation, NoLock);
 837         }
 838 }
 839
 840 /* ----------------------------------------------------------------
 841  *              ExecutePlan
 842  *
 843  *              processes the query plan to retrieve 'numberTuples' tuples in the
 844  *              direction specified.
 845  *              Retrieves all tuples if numberTuples is 0
 846  *
 847  *              result is either a slot containing the last tuple in the case
 848  *              of a SELECT or NULL otherwise.
 849  *
 850  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 851  * user can see it
 852  * ----------------------------------------------------------------
 853  */
 854 static TupleTableSlot *
 855 ExecutePlan(EState *estate,
 856                         PlanState *planstate,
 857                         CmdType operation,
 858                         long numberTuples,
 859                         ScanDirection direction,
 860                         DestReceiver *destfunc)
 861 {
 862         JunkFilter                      *junkfilter;
 863         TupleTableSlot          *slot;
 864         ItemPointer                      tupleid = NULL;
 865         ItemPointerData          tuple_ctid;
 866         long                             current_tuple_count;
 867         TupleTableSlot          *result;
 868
 869         /*
 870          * initialize local variables
 871          */
 872         slot = NULL;
 873         current_tuple_count = 0;
 874         result = NULL;
 875
 876         /*
 877          * Set the direction.
 878          */
 879         estate->es_direction = direction;
 880
 881         /*
 882          * Process BEFORE EACH STATEMENT triggers
 883          */
 884         switch (operation)
 885         {
 886                 case CMD_UPDATE:
 887                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 888                         break;
 889                 case CMD_DELETE:
 890                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 891                         break;
 892                 case CMD_INSERT:
 893                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 894                         break;
 895                 default:
 896                         /* do nothing */
 897                         break;
 898         }
 899
 900         /*
 901          * Loop until we've processed the proper number of tuples from the
 902          * plan.
 903          */
 904
 905         for (;;)
 906         {
 907                 /* Reset the per-output-tuple exprcontext */
 908                 ResetPerTupleExprContext(estate);
 909
 910                 /*
 911                  * Execute the plan and obtain a tuple
 912                  */
 913 lnext:  ;
 914                 if (estate->es_useEvalPlan)
 915                 {
 916                         slot = EvalPlanQualNext(estate);
 917                         if (TupIsNull(slot))
 918                                 slot = ExecProcNode(planstate);
 919                 }
 920                 else
 921                         slot = ExecProcNode(planstate);
 922
 923                 /*
 924                  * if the tuple is null, then we assume there is nothing more to
 925                  * process so we just return null...
 926                  */
 927                 if (TupIsNull(slot))
 928                 {
 929                         result = NULL;
 930                         break;
 931                 }
 932
 933                 /*
 934                  * if we have a junk filter, then project a new tuple with the
 935                  * junk removed.
 936                  *
 937                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 938                  * (Formerly, we stored it back over the "dirty" tuple, which is
 939                  * WRONG because that tuple slot has the wrong descriptor.)
 940                  *
 941                  * Also, extract all the junk information we need.
 942                  */
 943                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 944                 {
 945                         Datum           datum;
 946                         HeapTuple       newTuple;
 947                         bool            isNull;
 948
 949                         /*
 950                          * extract the 'ctid' junk attribute.
 951                          */
 952                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 953                         {
 954                                 if (!ExecGetJunkAttribute(junkfilter,
 955                                                                                   slot,
 956                                                                                   "ctid",
 957                                                                                   &datum,
 958                                                                                   &isNull))
 959                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 960
 961                                 /* shouldn't ever get a null result... */
 962                                 if (isNull)
 963                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 964
 965                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 966                                 tuple_ctid = *tupleid;  /* make sure we don't free the
 967                                                                                  * ctid!! */
 968                                 tupleid = &tuple_ctid;
 969                         }
 970                         else if (estate->es_rowMark != NIL)
 971                         {
 972                                 List       *l;
 973
 974                 lmark:  ;
 975                                 foreach(l, estate->es_rowMark)
 976                                 {
 977                                         execRowMark *erm = lfirst(l);
 978                                         Buffer          buffer;
 979                                         HeapTupleData tuple;
 980                                         TupleTableSlot *newSlot;
 981                                         int                     test;
 982
 983                                         if (!ExecGetJunkAttribute(junkfilter,
 984                                                                                           slot,
 985                                                                                           erm->resname,
 986                                                                                           &datum,
 987                                                                                           &isNull))
 988                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
 989                                                          erm->resname);
 990
 991                                         /* shouldn't ever get a null result... */
 992                                         if (isNull)
 993                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
 994                                                          erm->resname);
 995
 996                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
 997                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
 998                                                                                         estate->es_snapshot->curcid);
 999                                         ReleaseBuffer(buffer);
1000                                         switch (test)
1001                                         {
1002                                                 case HeapTupleSelfUpdated:
1003                                                         /* treat it as deleted; do not process */
1004                                                         goto lnext;
1005
1006                                                 case HeapTupleMayBeUpdated:
1007                                                         break;
1008
1009                                                 case HeapTupleUpdated:
1010                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1011                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1012                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1013                                                                   (ItemPointer) DatumGetPointer(datum))))
1014                                                         {
1015                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1016                                                                 if (!(TupIsNull(newSlot)))
1017                                                                 {
1018                                                                         slot = newSlot;
1019                                                                         estate->es_useEvalPlan = true;
1020                                                                         goto lmark;
1021                                                                 }
1022                                                         }
1023
1024                                                         /*
1025                                                          * if tuple was deleted or PlanQual failed for
1026                                                          * updated tuple - we must not return this
1027                                                          * tuple!
1028                                                          */
1029                                                         goto lnext;
1030
1031                                                 default:
1032                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1033                                                         return (NULL);
1034                                         }
1035                                 }
1036                         }
1037
1038                         /*
1039                          * Finally create a new "clean" tuple with all junk attributes
1040                          * removed
1041                          */
1042                         newTuple = ExecRemoveJunk(junkfilter, slot);
1043
1044                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1045                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1046                                                                   InvalidBuffer,                /* this tuple has no
1047                                                                                                                  * buffer */
1048                                                                   true);                /* tuple should be pfreed */
1049                 }
1050
1051                 /*
1052                  * now that we have a tuple, do the appropriate thing with it..
1053                  * either return it to the user, add it to a relation someplace,
1054                  * delete it from a relation, or modify some of its attributes.
1055                  */
1056                 switch (operation)
1057                 {
1058                         case CMD_SELECT:
1059                                 ExecSelect(slot,        /* slot containing tuple */
1060                                                    destfunc,    /* destination's tuple-receiver
1061                                                                                  * obj */
1062                                                    estate);
1063                                 result = slot;
1064                                 break;
1065
1066                         case CMD_INSERT:
1067                                 ExecInsert(slot, tupleid, estate);
1068                                 result = NULL;
1069                                 break;
1070
1071                         case CMD_DELETE:
1072                                 ExecDelete(slot, tupleid, estate);
1073                                 result = NULL;
1074                                 break;
1075
1076                         case CMD_UPDATE:
1077                                 ExecUpdate(slot, tupleid, estate);
1078                                 result = NULL;
1079                                 break;
1080
1081                         default:
1082                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1083                                 result = NULL;
1084                                 break;
1085                 }
1086
1087                 /*
1088                  * check our tuple count.. if we've processed the proper number
1089                  * then quit, else loop again and process more tuples.  Zero
1090                  * number_tuples means no limit.
1091                  */
1092                 current_tuple_count++;
1093                 if (numberTuples == current_tuple_count)
1094                         break;
1095         }
1096
1097         /*
1098          * Process AFTER EACH STATEMENT triggers
1099          */
1100         switch (operation)
1101         {
1102                 case CMD_UPDATE:
1103                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1104                         break;
1105                 case CMD_DELETE:
1106                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1107                         break;
1108                 case CMD_INSERT:
1109                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1110                         break;
1111                 default:
1112                         /* do nothing */
1113                         break;
1114         }
1115
1116         /*
1117          * here, result is either a slot containing a tuple in the case of a
1118          * SELECT or NULL otherwise.
1119          */
1120         return result;
1121 }
1122
1123 /* ----------------------------------------------------------------
1124  *              ExecSelect
1125  *
1126  *              SELECTs are easy.. we just pass the tuple to the appropriate
1127  *              print function.  The only complexity is when we do a
1128  *              "SELECT INTO", in which case we insert the tuple into
1129  *              the appropriate relation (note: this is a newly created relation
1130  *              so we don't need to worry about indices or locks.)
1131  * ----------------------------------------------------------------
1132  */
1133 static void
1134 ExecSelect(TupleTableSlot *slot,
1135                    DestReceiver *destfunc,
1136                    EState *estate)
1137 {
1138         HeapTuple       tuple;
1139         TupleDesc       attrtype;
1140
1141         /*
1142          * get the heap tuple out of the tuple table slot
1143          */
1144         tuple = slot->val;
1145         attrtype = slot->ttc_tupleDescriptor;
1146
1147         /*
1148          * insert the tuple into the "into relation"
1149          */
1150         if (estate->es_into_relation_descriptor != NULL)
1151         {
1152                 heap_insert(estate->es_into_relation_descriptor, tuple,
1153                                         estate->es_snapshot->curcid);
1154                 IncrAppended();
1155         }
1156
1157         /*
1158          * send the tuple to the front end (or the screen)
1159          */
1160         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1161         IncrRetrieved();
1162         (estate->es_processed)++;
1163 }
1164
1165 /* ----------------------------------------------------------------
1166  *              ExecInsert
1167  *
1168  *              INSERTs are trickier.. we have to insert the tuple into
1169  *              the base relation and insert appropriate tuples into the
1170  *              index relations.
1171  * ----------------------------------------------------------------
1172  */
1173 static void
1174 ExecInsert(TupleTableSlot *slot,
1175                    ItemPointer tupleid,
1176                    EState *estate)
1177 {
1178         HeapTuple       tuple;
1179         ResultRelInfo *resultRelInfo;
1180         Relation        resultRelationDesc;
1181         int                     numIndices;
1182         Oid                     newId;
1183
1184         /*
1185          * get the heap tuple out of the tuple table slot
1186          */
1187         tuple = slot->val;
1188
1189         /*
1190          * get information on the (current) result relation
1191          */
1192         resultRelInfo = estate->es_result_relation_info;
1193         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1194
1195         /* BEFORE ROW INSERT Triggers */
1196         if (resultRelInfo->ri_TrigDesc &&
1197                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1198         {
1199                 HeapTuple       newtuple;
1200
1201                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1202
1203                 if (newtuple == NULL)   /* "do nothing" */
1204                         return;
1205
1206                 if (newtuple != tuple)  /* modified by Trigger(s) */
1207                 {
1208                         /*
1209                          * Insert modified tuple into tuple table slot, replacing the
1210                          * original.  We assume that it was allocated in per-tuple
1211                          * memory context, and therefore will go away by itself. The
1212                          * tuple table slot should not try to clear it.
1213                          */
1214                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1215                         tuple = newtuple;
1216                 }
1217         }
1218
1219         /*
1220          * Check the constraints of the tuple
1221          */
1222         if (resultRelationDesc->rd_att->constr)
1223                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1224
1225         /*
1226          * insert the tuple
1227          */
1228         newId = heap_insert(resultRelationDesc, tuple,
1229                                                 estate->es_snapshot->curcid);
1230
1231         IncrAppended();
1232         (estate->es_processed)++;
1233         estate->es_lastoid = newId;
1234         setLastTid(&(tuple->t_self));
1235
1236         /*
1237          * process indices
1238          *
1239          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1240          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1241          * field.
1242          */
1243         numIndices = resultRelInfo->ri_NumIndices;
1244         if (numIndices > 0)
1245                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1246
1247         /* AFTER ROW INSERT Triggers */
1248         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1249 }
1250
1251 /* ----------------------------------------------------------------
1252  *              ExecDelete
1253  *
1254  *              DELETE is like UPDATE, we delete the tuple and its
1255  *              index tuples.
1256  * ----------------------------------------------------------------
1257  */
1258 static void
1259 ExecDelete(TupleTableSlot *slot,
1260                    ItemPointer tupleid,
1261                    EState *estate)
1262 {
1263         ResultRelInfo *resultRelInfo;
1264         Relation        resultRelationDesc;
1265         ItemPointerData ctid;
1266         int                     result;
1267
1268         /*
1269          * get information on the (current) result relation
1270          */
1271         resultRelInfo = estate->es_result_relation_info;
1272         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1273
1274         /* BEFORE ROW DELETE Triggers */
1275         if (resultRelInfo->ri_TrigDesc &&
1276           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1277         {
1278                 bool            dodelete;
1279
1280                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1281
1282                 if (!dodelete)                  /* "do nothing" */
1283                         return;
1284         }
1285
1286         /*
1287          * delete the tuple
1288          */
1289 ldelete:;
1290         result = heap_delete(resultRelationDesc, tupleid,
1291                                                  &ctid,
1292                                                  estate->es_snapshot->curcid);
1293         switch (result)
1294         {
1295                 case HeapTupleSelfUpdated:
1296                         /* already deleted by self; nothing to do */
1297                         return;
1298
1299                 case HeapTupleMayBeUpdated:
1300                         break;
1301
1302                 case HeapTupleUpdated:
1303                         if (XactIsoLevel == XACT_SERIALIZABLE)
1304                                 elog(ERROR, "Can't serialize access due to concurrent update");
1305                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1306                         {
1307                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1308                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1309
1310                                 if (!TupIsNull(epqslot))
1311                                 {
1312                                         *tupleid = ctid;
1313                                         goto ldelete;
1314                                 }
1315                         }
1316                         /* tuple already deleted; nothing to do */
1317                         return;
1318
1319                 default:
1320                         elog(ERROR, "Unknown status %u from heap_delete", result);
1321                         return;
1322         }
1323
1324         IncrDeleted();
1325         (estate->es_processed)++;
1326
1327         /*
1328          * Note: Normally one would think that we have to delete index tuples
1329          * associated with the heap tuple now..
1330          *
1331          * ... but in POSTGRES, we have no need to do this because the vacuum
1332          * daemon automatically opens an index scan and deletes index tuples
1333          * when it finds deleted heap tuples. -cim 9/27/89
1334          */
1335
1336         /* AFTER ROW DELETE Triggers */
1337         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1338 }
1339
1340 /* ----------------------------------------------------------------
1341  *              ExecUpdate
1342  *
1343  *              note: we can't run UPDATE queries with transactions
1344  *              off because UPDATEs are actually INSERTs and our
1345  *              scan will mistakenly loop forever, updating the tuple
1346  *              it just inserted..      This should be fixed but until it
1347  *              is, we don't want to get stuck in an infinite loop
1348  *              which corrupts your database..
1349  * ----------------------------------------------------------------
1350  */
1351 static void
1352 ExecUpdate(TupleTableSlot *slot,
1353                    ItemPointer tupleid,
1354                    EState *estate)
1355 {
1356         HeapTuple       tuple;
1357         ResultRelInfo *resultRelInfo;
1358         Relation        resultRelationDesc;
1359         ItemPointerData ctid;
1360         int                     result;
1361         int                     numIndices;
1362
1363         /*
1364          * abort the operation if not running transactions
1365          */
1366         if (IsBootstrapProcessingMode())
1367         {
1368                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1369                 return;
1370         }
1371
1372         /*
1373          * get the heap tuple out of the tuple table slot
1374          */
1375         tuple = slot->val;
1376
1377         /*
1378          * get information on the (current) result relation
1379          */
1380         resultRelInfo = estate->es_result_relation_info;
1381         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1382
1383         /* BEFORE ROW UPDATE Triggers */
1384         if (resultRelInfo->ri_TrigDesc &&
1385           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1386         {
1387                 HeapTuple       newtuple;
1388
1389                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1390                                                                                 tupleid, tuple);
1391
1392                 if (newtuple == NULL)   /* "do nothing" */
1393                         return;
1394
1395                 if (newtuple != tuple)  /* modified by Trigger(s) */
1396                 {
1397                         /*
1398                          * Insert modified tuple into tuple table slot, replacing the
1399                          * original.  We assume that it was allocated in per-tuple
1400                          * memory context, and therefore will go away by itself. The
1401                          * tuple table slot should not try to clear it.
1402                          */
1403                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1404                         tuple = newtuple;
1405                 }
1406         }
1407
1408         /*
1409          * Check the constraints of the tuple
1410          *
1411          * If we generate a new candidate tuple after EvalPlanQual testing, we
1412          * must loop back here and recheck constraints.  (We don't need to
1413          * redo triggers, however.      If there are any BEFORE triggers then
1414          * trigger.c will have done mark4update to lock the correct tuple, so
1415          * there's no need to do them again.)
1416          */
1417 lreplace:;
1418         if (resultRelationDesc->rd_att->constr)
1419                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1420
1421         /*
1422          * replace the heap tuple
1423          */
1424         result = heap_update(resultRelationDesc, tupleid, tuple,
1425                                                  &ctid,
1426                                                  estate->es_snapshot->curcid);
1427         switch (result)
1428         {
1429                 case HeapTupleSelfUpdated:
1430                         /* already deleted by self; nothing to do */
1431                         return;
1432
1433                 case HeapTupleMayBeUpdated:
1434                         break;
1435
1436                 case HeapTupleUpdated:
1437                         if (XactIsoLevel == XACT_SERIALIZABLE)
1438                                 elog(ERROR, "Can't serialize access due to concurrent update");
1439                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1440                         {
1441                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1442                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1443
1444                                 if (!TupIsNull(epqslot))
1445                                 {
1446                                         *tupleid = ctid;
1447                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1448                                         slot = ExecStoreTuple(tuple,
1449                                                                         estate->es_junkFilter->jf_resultSlot,
1450                                                                                   InvalidBuffer, true);
1451                                         goto lreplace;
1452                                 }
1453                         }
1454                         /* tuple already deleted; nothing to do */
1455                         return;
1456
1457                 default:
1458                         elog(ERROR, "Unknown status %u from heap_update", result);
1459                         return;
1460         }
1461
1462         IncrReplaced();
1463         (estate->es_processed)++;
1464
1465         /*
1466          * Note: instead of having to update the old index tuples associated
1467          * with the heap tuple, all we do is form and insert new index tuples.
1468          * This is because UPDATEs are actually DELETEs and INSERTs and index
1469          * tuple deletion is done automagically by the vacuum daemon. All we
1470          * do is insert new index tuples.  -cim 9/27/89
1471          */
1472
1473         /*
1474          * process indices
1475          *
1476          * heap_update updates a tuple in the base relation by invalidating it
1477          * and then inserting a new tuple to the relation.      As a side effect,
1478          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1479          * field.  So we now insert index tuples using the new tupleid stored
1480          * there.
1481          */
1482
1483         numIndices = resultRelInfo->ri_NumIndices;
1484         if (numIndices > 0)
1485                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1486
1487         /* AFTER ROW UPDATE Triggers */
1488         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1489 }
1490
1491 static char *
1492 ExecRelCheck(ResultRelInfo *resultRelInfo,
1493                          TupleTableSlot *slot, EState *estate)
1494 {
1495         Relation        rel = resultRelInfo->ri_RelationDesc;
1496         int                     ncheck = rel->rd_att->constr->num_check;
1497         ConstrCheck *check = rel->rd_att->constr->check;
1498         ExprContext *econtext;
1499         MemoryContext oldContext;
1500         List       *qual;
1501         int                     i;
1502
1503         /*
1504          * If first time through for this result relation, build expression
1505          * nodetrees for rel's constraint expressions.  Keep them in the
1506          * per-query memory context so they'll survive throughout the query.
1507          */
1508         if (resultRelInfo->ri_ConstraintExprs == NULL)
1509         {
1510                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1511                 resultRelInfo->ri_ConstraintExprs =
1512                         (List **) palloc(ncheck * sizeof(List *));
1513                 for (i = 0; i < ncheck; i++)
1514                 {
1515                         qual = (List *) stringToNode(check[i].ccbin);
1516                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1517                                 ExecPrepareExpr((Expr *) qual, estate);
1518                 }
1519                 MemoryContextSwitchTo(oldContext);
1520         }
1521
1522         /*
1523          * We will use the EState's per-tuple context for evaluating
1524          * constraint expressions (creating it if it's not already there).
1525          */
1526         econtext = GetPerTupleExprContext(estate);
1527
1528         /* Arrange for econtext's scan tuple to be the tuple under test */
1529         econtext->ecxt_scantuple = slot;
1530
1531         /* And evaluate the constraints */
1532         for (i = 0; i < ncheck; i++)
1533         {
1534                 qual = resultRelInfo->ri_ConstraintExprs[i];
1535
1536                 /*
1537                  * NOTE: SQL92 specifies that a NULL result from a constraint
1538                  * expression is not to be treated as a failure.  Therefore, tell
1539                  * ExecQual to return TRUE for NULL.
1540                  */
1541                 if (!ExecQual(qual, econtext, true))
1542                         return check[i].ccname;
1543         }
1544
1545         /* NULL result means no error */
1546         return (char *) NULL;
1547 }
1548
1549 void
1550 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1551                                 TupleTableSlot *slot, EState *estate)
1552 {
1553         Relation        rel = resultRelInfo->ri_RelationDesc;
1554         HeapTuple       tuple = slot->val;
1555         TupleConstr *constr = rel->rd_att->constr;
1556
1557         Assert(constr);
1558
1559         if (constr->has_not_null)
1560         {
1561                 int                     natts = rel->rd_att->natts;
1562                 int                     attrChk;
1563
1564                 for (attrChk = 1; attrChk <= natts; attrChk++)
1565                 {
1566                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1567                                 heap_attisnull(tuple, attrChk))
1568                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1569                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1570                 }
1571         }
1572
1573         if (constr->num_check > 0)
1574         {
1575                 char       *failed;
1576
1577                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1578                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1579                                  caller, failed, RelationGetRelationName(rel));
1580         }
1581 }
1582
1583 /*
1584  * Check a modified tuple to see if we want to process its updated version
1585  * under READ COMMITTED rules.
1586  *
1587  * See backend/executor/README for some info about how this works.
1588  */
1589 TupleTableSlot *
1590 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1591 {
1592         evalPlanQual *epq;
1593         EState     *epqstate;
1594         Relation        relation;
1595         HeapTupleData tuple;
1596         HeapTuple       copyTuple = NULL;
1597         int                     rtsize;
1598         bool            endNode;
1599
1600         Assert(rti != 0);
1601
1602         /*
1603          * find relation containing target tuple
1604          */
1605         if (estate->es_result_relation_info != NULL &&
1606                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1607                 relation = estate->es_result_relation_info->ri_RelationDesc;
1608         else
1609         {
1610                 List       *l;
1611
1612                 relation = NULL;
1613                 foreach(l, estate->es_rowMark)
1614                 {
1615                         if (((execRowMark *) lfirst(l))->rti == rti)
1616                         {
1617                                 relation = ((execRowMark *) lfirst(l))->relation;
1618                                 break;
1619                         }
1620                 }
1621                 if (relation == NULL)
1622                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1623         }
1624
1625         /*
1626          * fetch tid tuple
1627          *
1628          * Loop here to deal with updated or busy tuples
1629          */
1630         tuple.t_self = *tid;
1631         for (;;)
1632         {
1633                 Buffer          buffer;
1634
1635                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1636                 {
1637                         TransactionId xwait = SnapshotDirty->xmax;
1638
1639                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1640                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1641
1642                         /*
1643                          * If tuple is being updated by other transaction then we have
1644                          * to wait for its commit/abort.
1645                          */
1646                         if (TransactionIdIsValid(xwait))
1647                         {
1648                                 ReleaseBuffer(buffer);
1649                                 XactLockTableWait(xwait);
1650                                 continue;
1651                         }
1652
1653                         /*
1654                          * We got tuple - now copy it for use by recheck query.
1655                          */
1656                         copyTuple = heap_copytuple(&tuple);
1657                         ReleaseBuffer(buffer);
1658                         break;
1659                 }
1660
1661                 /*
1662                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1663                  * Note that it's possible to get invalid SnapshotDirty->tid if
1664                  * tuple updated by this transaction. Have we to check this ?
1665                  */
1666                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1667                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1668                 {
1669                         /* updated, so look at the updated copy */
1670                         tuple.t_self = SnapshotDirty->tid;
1671                         continue;
1672                 }
1673
1674                 /*
1675                  * Deleted or updated by this transaction; forget it.
1676                  */
1677                 return NULL;
1678         }
1679
1680         /*
1681          * For UPDATE/DELETE we have to return tid of actual row we're
1682          * executing PQ for.
1683          */
1684         *tid = tuple.t_self;
1685
1686         /*
1687          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1688          */
1689         epq = (evalPlanQual *) estate->es_evalPlanQual;
1690         rtsize = length(estate->es_range_table);
1691         endNode = true;
1692
1693         if (epq != NULL && epq->rti == 0)
1694         {
1695                 /* Top PQ stack entry is idle, so re-use it */
1696                 Assert(!(estate->es_useEvalPlan) &&
1697                            epq->estate.es_evalPlanQual == NULL);
1698                 epq->rti = rti;
1699                 endNode = false;
1700         }
1701
1702         /*
1703          * If this is request for another RTE - Ra, - then we have to check
1704          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1705          * updated again and we have to re-start old execution for Ra and
1706          * forget all what we done after Ra was suspended. Cool? -:))
1707          */
1708         if (epq != NULL && epq->rti != rti &&
1709                 epq->estate.es_evTuple[rti - 1] != NULL)
1710         {
1711                 do
1712                 {
1713                         evalPlanQual *oldepq;
1714
1715                         /* pop previous PlanQual from the stack */
1716                         epqstate = &(epq->estate);
1717                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1718                         Assert(oldepq->rti != 0);
1719                         /* stop execution */
1720                         ExecEndNode(epq->planstate);
1721                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1722                         epqstate->es_tupleTable = NULL;
1723                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1724                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1725                         /* push current PQ to freePQ stack */
1726                         oldepq->free = epq;
1727                         epq = oldepq;
1728                         estate->es_evalPlanQual = (Pointer) epq;
1729                 } while (epq->rti != rti);
1730         }
1731
1732         /*
1733          * If we are requested for another RTE then we have to suspend
1734          * execution of current PlanQual and start execution for new one.
1735          */
1736         if (epq == NULL || epq->rti != rti)
1737         {
1738                 /* try to reuse plan used previously */
1739                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1740
1741                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1742                 {
1743                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1744                         newepq->free = NULL;
1745
1746                         /*
1747                          * Each stack level has its own copy of the plan tree.  This
1748                          * is wasteful, but necessary until plan trees are fully
1749                          * read-only.
1750                          */
1751                         newepq->plan = copyObject(estate->es_origPlan);
1752
1753                         /*
1754                          * Init stack level's EState.  We share top level's copy of
1755                          * es_result_relations array and other non-changing status. We
1756                          * need our own tupletable, es_param_exec_vals, and other
1757                          * changeable state.
1758                          */
1759                         epqstate = &(newepq->estate);
1760                         memcpy(epqstate, estate, sizeof(EState));
1761                         epqstate->es_direction = ForwardScanDirection;
1762                         if (estate->es_origPlan->nParamExec > 0)
1763                                 epqstate->es_param_exec_vals = (ParamExecData *)
1764                                         palloc(estate->es_origPlan->nParamExec *
1765                                                    sizeof(ParamExecData));
1766                         epqstate->es_tupleTable = NULL;
1767                         epqstate->es_per_tuple_exprcontext = NULL;
1768
1769                         /*
1770                          * Each epqstate must have its own es_evTupleNull state, but
1771                          * all the stack entries share es_evTuple state.  This allows
1772                          * sub-rechecks to inherit the value being examined by an
1773                          * outer recheck.
1774                          */
1775                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1776                         if (epq == NULL)
1777                                 /* first PQ stack entry */
1778                                 epqstate->es_evTuple = (HeapTuple *)
1779                                         palloc0(rtsize * sizeof(HeapTuple));
1780                         else
1781                                 /* later stack entries share the same storage */
1782                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1783                 }
1784                 else
1785                 {
1786                         /* recycle previously used EState */
1787                         epqstate = &(newepq->estate);
1788                 }
1789                 /* push current PQ to the stack */
1790                 epqstate->es_evalPlanQual = (Pointer) epq;
1791                 epq = newepq;
1792                 estate->es_evalPlanQual = (Pointer) epq;
1793                 epq->rti = rti;
1794                 endNode = false;
1795         }
1796
1797         Assert(epq->rti == rti);
1798         epqstate = &(epq->estate);
1799
1800         /*
1801          * Ok - we're requested for the same RTE.  Unfortunately we still have
1802          * to end and restart execution of the plan, because ExecReScan
1803          * wouldn't ensure that upper plan nodes would reset themselves.  We
1804          * could make that work if insertion of the target tuple were
1805          * integrated with the Param mechanism somehow, so that the upper plan
1806          * nodes know that their children's outputs have changed.
1807          */
1808         if (endNode)
1809         {
1810                 /* stop execution */
1811                 ExecEndNode(epq->planstate);
1812                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1813                 epqstate->es_tupleTable = NULL;
1814         }
1815
1816         /*
1817          * free old RTE' tuple, if any, and store target tuple where
1818          * relation's scan node will see it
1819          */
1820         if (epqstate->es_evTuple[rti - 1] != NULL)
1821                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1822         epqstate->es_evTuple[rti - 1] = copyTuple;
1823
1824         /*
1825          * Initialize for new recheck query; be careful to copy down state
1826          * that might have changed in top EState.
1827          */
1828         epqstate->es_result_relation_info = estate->es_result_relation_info;
1829         epqstate->es_junkFilter = estate->es_junkFilter;
1830         if (estate->es_origPlan->nParamExec > 0)
1831                 memset(epqstate->es_param_exec_vals, 0,
1832                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1833         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1834         epqstate->es_useEvalPlan = false;
1835         Assert(epqstate->es_tupleTable == NULL);
1836         epqstate->es_tupleTable =
1837                 ExecCreateTupleTable(estate->es_tupleTable->size);
1838
1839         epq->planstate = ExecInitNode(epq->plan, epqstate);
1840
1841         return EvalPlanQualNext(estate);
1842 }
1843
1844 static TupleTableSlot *
1845 EvalPlanQualNext(EState *estate)
1846 {
1847         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1848         EState     *epqstate = &(epq->estate);
1849         evalPlanQual *oldepq;
1850         TupleTableSlot *slot;
1851
1852         Assert(epq->rti != 0);
1853
1854 lpqnext:;
1855         slot = ExecProcNode(epq->planstate);
1856
1857         /*
1858          * No more tuples for this PQ. Continue previous one.
1859          */
1860         if (TupIsNull(slot))
1861         {
1862                 /* stop execution */
1863                 ExecEndNode(epq->planstate);
1864                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1865                 epqstate->es_tupleTable = NULL;
1866                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1867                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1868                 /* pop old PQ from the stack */
1869                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1870                 if (oldepq == (evalPlanQual *) NULL)
1871                 {
1872                         epq->rti = 0;           /* this is the first (oldest) */
1873                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1874                         return (NULL);          /* continue Query execution   */
1875                 }
1876                 Assert(oldepq->rti != 0);
1877                 /* push current PQ to freePQ stack */
1878                 oldepq->free = epq;
1879                 epq = oldepq;
1880                 epqstate = &(epq->estate);
1881                 estate->es_evalPlanQual = (Pointer) epq;
1882                 goto lpqnext;
1883         }
1884
1885         return (slot);
1886 }
1887
1888 static void
1889 EndEvalPlanQual(EState *estate)
1890 {
1891         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1892         EState     *epqstate = &(epq->estate);
1893         evalPlanQual *oldepq;
1894
1895         if (epq->rti == 0)                      /* plans already shutdowned */
1896         {
1897                 Assert(epq->estate.es_evalPlanQual == NULL);
1898                 return;
1899         }
1900
1901         for (;;)
1902         {
1903                 /* stop execution */
1904                 ExecEndNode(epq->planstate);
1905                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1906                 epqstate->es_tupleTable = NULL;
1907                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1908                 {
1909                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1910                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1911                 }
1912                 /* pop old PQ from the stack */
1913                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1914                 if (oldepq == (evalPlanQual *) NULL)
1915                 {
1916                         epq->rti = 0;           /* this is the first (oldest) */
1917                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1918                         break;
1919                 }
1920                 Assert(oldepq->rti != 0);
1921                 /* push current PQ to freePQ stack */
1922                 oldepq->free = epq;
1923                 epq = oldepq;
1924                 epqstate = &(epq->estate);
1925                 estate->es_evalPlanQual = (Pointer) epq;
1926         }
1927 }