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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.193 2002/12/15 16:17:45 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  */
 780 void
 781 ExecEndPlan(PlanState *planstate, EState *estate)
 782 {
 783         ResultRelInfo *resultRelInfo;
 784         int                     i;
 785         List       *l;
 786
 787         /*
 788          * shut down any PlanQual processing we were doing
 789          */
 790         if (estate->es_evalPlanQual != NULL)
 791                 EndEvalPlanQual(estate);
 792
 793         /*
 794          * shut down the node-type-specific query processing
 795          */
 796         ExecEndNode(planstate);
 797
 798         /*
 799          * destroy the executor "tuple" table.
 800          */
 801         ExecDropTupleTable(estate->es_tupleTable, true);
 802         estate->es_tupleTable = NULL;
 803
 804         /*
 805          * close the result relation(s) if any, but hold locks until xact
 806          * commit.      Also clean up junkfilters if present.
 807          */
 808         resultRelInfo = estate->es_result_relations;
 809         for (i = estate->es_num_result_relations; i > 0; i--)
 810         {
 811                 /* Close indices and then the relation itself */
 812                 ExecCloseIndices(resultRelInfo);
 813                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 814                 /* Delete the junkfilter if any */
 815                 if (resultRelInfo->ri_junkFilter != NULL)
 816                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 817                 resultRelInfo++;
 818         }
 819
 820         /*
 821          * close the "into" relation if necessary, again keeping lock
 822          */
 823         if (estate->es_into_relation_descriptor != NULL)
 824                 heap_close(estate->es_into_relation_descriptor, NoLock);
 825
 826         /*
 827          * There might be a junkfilter without a result relation.
 828          */
 829         if (estate->es_num_result_relations == 0 &&
 830                 estate->es_junkFilter != NULL)
 831         {
 832                 ExecFreeJunkFilter(estate->es_junkFilter);
 833                 estate->es_junkFilter = NULL;
 834         }
 835
 836         /*
 837          * close any relations selected FOR UPDATE, again keeping locks
 838          */
 839         foreach(l, estate->es_rowMark)
 840         {
 841                 execRowMark *erm = lfirst(l);
 842
 843                 heap_close(erm->relation, NoLock);
 844         }
 845 }
 846
 847 /* ----------------------------------------------------------------
 848  *              ExecutePlan
 849  *
 850  *              processes the query plan to retrieve 'numberTuples' tuples in the
 851  *              direction specified.
 852  *              Retrieves all tuples if numberTuples is 0
 853  *
 854  *              result is either a slot containing the last tuple in the case
 855  *              of a SELECT or NULL otherwise.
 856  *
 857  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 858  * user can see it
 859  * ----------------------------------------------------------------
 860  */
 861 static TupleTableSlot *
 862 ExecutePlan(EState *estate,
 863                         PlanState *planstate,
 864                         CmdType operation,
 865                         long numberTuples,
 866                         ScanDirection direction,
 867                         DestReceiver *destfunc)
 868 {
 869         JunkFilter                      *junkfilter;
 870         TupleTableSlot          *slot;
 871         ItemPointer                      tupleid = NULL;
 872         ItemPointerData          tuple_ctid;
 873         long                             current_tuple_count;
 874         TupleTableSlot          *result;
 875
 876         /*
 877          * initialize local variables
 878          */
 879         slot = NULL;
 880         current_tuple_count = 0;
 881         result = NULL;
 882
 883         /*
 884          * Set the direction.
 885          */
 886         estate->es_direction = direction;
 887
 888         /*
 889          * Process BEFORE EACH STATEMENT triggers
 890          */
 891         switch (operation)
 892         {
 893                 case CMD_UPDATE:
 894                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 895                         break;
 896                 case CMD_DELETE:
 897                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 898                         break;
 899                 case CMD_INSERT:
 900                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 901                         break;
 902                 default:
 903                         /* do nothing */
 904                         break;
 905         }
 906
 907         /*
 908          * Loop until we've processed the proper number of tuples from the
 909          * plan.
 910          */
 911
 912         for (;;)
 913         {
 914                 /* Reset the per-output-tuple exprcontext */
 915                 ResetPerTupleExprContext(estate);
 916
 917                 /*
 918                  * Execute the plan and obtain a tuple
 919                  */
 920 lnext:  ;
 921                 if (estate->es_useEvalPlan)
 922                 {
 923                         slot = EvalPlanQualNext(estate);
 924                         if (TupIsNull(slot))
 925                                 slot = ExecProcNode(planstate);
 926                 }
 927                 else
 928                         slot = ExecProcNode(planstate);
 929
 930                 /*
 931                  * if the tuple is null, then we assume there is nothing more to
 932                  * process so we just return null...
 933                  */
 934                 if (TupIsNull(slot))
 935                 {
 936                         result = NULL;
 937                         break;
 938                 }
 939
 940                 /*
 941                  * if we have a junk filter, then project a new tuple with the
 942                  * junk removed.
 943                  *
 944                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 945                  * (Formerly, we stored it back over the "dirty" tuple, which is
 946                  * WRONG because that tuple slot has the wrong descriptor.)
 947                  *
 948                  * Also, extract all the junk information we need.
 949                  */
 950                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 951                 {
 952                         Datum           datum;
 953                         HeapTuple       newTuple;
 954                         bool            isNull;
 955
 956                         /*
 957                          * extract the 'ctid' junk attribute.
 958                          */
 959                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 960                         {
 961                                 if (!ExecGetJunkAttribute(junkfilter,
 962                                                                                   slot,
 963                                                                                   "ctid",
 964                                                                                   &datum,
 965                                                                                   &isNull))
 966                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 967
 968                                 /* shouldn't ever get a null result... */
 969                                 if (isNull)
 970                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 971
 972                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 973                                 tuple_ctid = *tupleid;  /* make sure we don't free the
 974                                                                                  * ctid!! */
 975                                 tupleid = &tuple_ctid;
 976                         }
 977                         else if (estate->es_rowMark != NIL)
 978                         {
 979                                 List       *l;
 980
 981                 lmark:  ;
 982                                 foreach(l, estate->es_rowMark)
 983                                 {
 984                                         execRowMark *erm = lfirst(l);
 985                                         Buffer          buffer;
 986                                         HeapTupleData tuple;
 987                                         TupleTableSlot *newSlot;
 988                                         int                     test;
 989
 990                                         if (!ExecGetJunkAttribute(junkfilter,
 991                                                                                           slot,
 992                                                                                           erm->resname,
 993                                                                                           &datum,
 994                                                                                           &isNull))
 995                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
 996                                                          erm->resname);
 997
 998                                         /* shouldn't ever get a null result... */
 999                                         if (isNull)
1000                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1001                                                          erm->resname);
1002
1003                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1004                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1005                                                                                         estate->es_snapshot->curcid);
1006                                         ReleaseBuffer(buffer);
1007                                         switch (test)
1008                                         {
1009                                                 case HeapTupleSelfUpdated:
1010                                                         /* treat it as deleted; do not process */
1011                                                         goto lnext;
1012
1013                                                 case HeapTupleMayBeUpdated:
1014                                                         break;
1015
1016                                                 case HeapTupleUpdated:
1017                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1018                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1019                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1020                                                                   (ItemPointer) DatumGetPointer(datum))))
1021                                                         {
1022                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1023                                                                 if (!(TupIsNull(newSlot)))
1024                                                                 {
1025                                                                         slot = newSlot;
1026                                                                         estate->es_useEvalPlan = true;
1027                                                                         goto lmark;
1028                                                                 }
1029                                                         }
1030
1031                                                         /*
1032                                                          * if tuple was deleted or PlanQual failed for
1033                                                          * updated tuple - we must not return this
1034                                                          * tuple!
1035                                                          */
1036                                                         goto lnext;
1037
1038                                                 default:
1039                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1040                                                         return (NULL);
1041                                         }
1042                                 }
1043                         }
1044
1045                         /*
1046                          * Finally create a new "clean" tuple with all junk attributes
1047                          * removed
1048                          */
1049                         newTuple = ExecRemoveJunk(junkfilter, slot);
1050
1051                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1052                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1053                                                                   InvalidBuffer,                /* this tuple has no
1054                                                                                                                  * buffer */
1055                                                                   true);                /* tuple should be pfreed */
1056                 }
1057
1058                 /*
1059                  * now that we have a tuple, do the appropriate thing with it..
1060                  * either return it to the user, add it to a relation someplace,
1061                  * delete it from a relation, or modify some of its attributes.
1062                  */
1063                 switch (operation)
1064                 {
1065                         case CMD_SELECT:
1066                                 ExecSelect(slot,        /* slot containing tuple */
1067                                                    destfunc,    /* destination's tuple-receiver
1068                                                                                  * obj */
1069                                                    estate);
1070                                 result = slot;
1071                                 break;
1072
1073                         case CMD_INSERT:
1074                                 ExecInsert(slot, tupleid, estate);
1075                                 result = NULL;
1076                                 break;
1077
1078                         case CMD_DELETE:
1079                                 ExecDelete(slot, tupleid, estate);
1080                                 result = NULL;
1081                                 break;
1082
1083                         case CMD_UPDATE:
1084                                 ExecUpdate(slot, tupleid, estate);
1085                                 result = NULL;
1086                                 break;
1087
1088                         default:
1089                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1090                                 result = NULL;
1091                                 break;
1092                 }
1093
1094                 /*
1095                  * check our tuple count.. if we've processed the proper number
1096                  * then quit, else loop again and process more tuples.  Zero
1097                  * number_tuples means no limit.
1098                  */
1099                 current_tuple_count++;
1100                 if (numberTuples == current_tuple_count)
1101                         break;
1102         }
1103
1104         /*
1105          * Process AFTER EACH STATEMENT triggers
1106          */
1107         switch (operation)
1108         {
1109                 case CMD_UPDATE:
1110                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1111                         break;
1112                 case CMD_DELETE:
1113                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1114                         break;
1115                 case CMD_INSERT:
1116                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1117                         break;
1118                 default:
1119                         /* do nothing */
1120                         break;
1121         }
1122
1123         /*
1124          * here, result is either a slot containing a tuple in the case of a
1125          * SELECT or NULL otherwise.
1126          */
1127         return result;
1128 }
1129
1130 /* ----------------------------------------------------------------
1131  *              ExecSelect
1132  *
1133  *              SELECTs are easy.. we just pass the tuple to the appropriate
1134  *              print function.  The only complexity is when we do a
1135  *              "SELECT INTO", in which case we insert the tuple into
1136  *              the appropriate relation (note: this is a newly created relation
1137  *              so we don't need to worry about indices or locks.)
1138  * ----------------------------------------------------------------
1139  */
1140 static void
1141 ExecSelect(TupleTableSlot *slot,
1142                    DestReceiver *destfunc,
1143                    EState *estate)
1144 {
1145         HeapTuple       tuple;
1146         TupleDesc       attrtype;
1147
1148         /*
1149          * get the heap tuple out of the tuple table slot
1150          */
1151         tuple = slot->val;
1152         attrtype = slot->ttc_tupleDescriptor;
1153
1154         /*
1155          * insert the tuple into the "into relation"
1156          */
1157         if (estate->es_into_relation_descriptor != NULL)
1158         {
1159                 heap_insert(estate->es_into_relation_descriptor, tuple,
1160                                         estate->es_snapshot->curcid);
1161                 IncrAppended();
1162         }
1163
1164         /*
1165          * send the tuple to the front end (or the screen)
1166          */
1167         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1168         IncrRetrieved();
1169         (estate->es_processed)++;
1170 }
1171
1172 /* ----------------------------------------------------------------
1173  *              ExecInsert
1174  *
1175  *              INSERTs are trickier.. we have to insert the tuple into
1176  *              the base relation and insert appropriate tuples into the
1177  *              index relations.
1178  * ----------------------------------------------------------------
1179  */
1180 static void
1181 ExecInsert(TupleTableSlot *slot,
1182                    ItemPointer tupleid,
1183                    EState *estate)
1184 {
1185         HeapTuple       tuple;
1186         ResultRelInfo *resultRelInfo;
1187         Relation        resultRelationDesc;
1188         int                     numIndices;
1189         Oid                     newId;
1190
1191         /*
1192          * get the heap tuple out of the tuple table slot
1193          */
1194         tuple = slot->val;
1195
1196         /*
1197          * get information on the (current) result relation
1198          */
1199         resultRelInfo = estate->es_result_relation_info;
1200         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1201
1202         /* BEFORE ROW INSERT Triggers */
1203         if (resultRelInfo->ri_TrigDesc &&
1204                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1205         {
1206                 HeapTuple       newtuple;
1207
1208                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1209
1210                 if (newtuple == NULL)   /* "do nothing" */
1211                         return;
1212
1213                 if (newtuple != tuple)  /* modified by Trigger(s) */
1214                 {
1215                         /*
1216                          * Insert modified tuple into tuple table slot, replacing the
1217                          * original.  We assume that it was allocated in per-tuple
1218                          * memory context, and therefore will go away by itself. The
1219                          * tuple table slot should not try to clear it.
1220                          */
1221                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1222                         tuple = newtuple;
1223                 }
1224         }
1225
1226         /*
1227          * Check the constraints of the tuple
1228          */
1229         if (resultRelationDesc->rd_att->constr)
1230                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1231
1232         /*
1233          * insert the tuple
1234          */
1235         newId = heap_insert(resultRelationDesc, tuple,
1236                                                 estate->es_snapshot->curcid);
1237
1238         IncrAppended();
1239         (estate->es_processed)++;
1240         estate->es_lastoid = newId;
1241         setLastTid(&(tuple->t_self));
1242
1243         /*
1244          * process indices
1245          *
1246          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1247          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1248          * field.
1249          */
1250         numIndices = resultRelInfo->ri_NumIndices;
1251         if (numIndices > 0)
1252                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1253
1254         /* AFTER ROW INSERT Triggers */
1255         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1256 }
1257
1258 /* ----------------------------------------------------------------
1259  *              ExecDelete
1260  *
1261  *              DELETE is like UPDATE, we delete the tuple and its
1262  *              index tuples.
1263  * ----------------------------------------------------------------
1264  */
1265 static void
1266 ExecDelete(TupleTableSlot *slot,
1267                    ItemPointer tupleid,
1268                    EState *estate)
1269 {
1270         ResultRelInfo *resultRelInfo;
1271         Relation        resultRelationDesc;
1272         ItemPointerData ctid;
1273         int                     result;
1274
1275         /*
1276          * get information on the (current) result relation
1277          */
1278         resultRelInfo = estate->es_result_relation_info;
1279         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1280
1281         /* BEFORE ROW DELETE Triggers */
1282         if (resultRelInfo->ri_TrigDesc &&
1283           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1284         {
1285                 bool            dodelete;
1286
1287                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1288
1289                 if (!dodelete)                  /* "do nothing" */
1290                         return;
1291         }
1292
1293         /*
1294          * delete the tuple
1295          */
1296 ldelete:;
1297         result = heap_delete(resultRelationDesc, tupleid,
1298                                                  &ctid,
1299                                                  estate->es_snapshot->curcid);
1300         switch (result)
1301         {
1302                 case HeapTupleSelfUpdated:
1303                         /* already deleted by self; nothing to do */
1304                         return;
1305
1306                 case HeapTupleMayBeUpdated:
1307                         break;
1308
1309                 case HeapTupleUpdated:
1310                         if (XactIsoLevel == XACT_SERIALIZABLE)
1311                                 elog(ERROR, "Can't serialize access due to concurrent update");
1312                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1313                         {
1314                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1315                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1316
1317                                 if (!TupIsNull(epqslot))
1318                                 {
1319                                         *tupleid = ctid;
1320                                         goto ldelete;
1321                                 }
1322                         }
1323                         /* tuple already deleted; nothing to do */
1324                         return;
1325
1326                 default:
1327                         elog(ERROR, "Unknown status %u from heap_delete", result);
1328                         return;
1329         }
1330
1331         IncrDeleted();
1332         (estate->es_processed)++;
1333
1334         /*
1335          * Note: Normally one would think that we have to delete index tuples
1336          * associated with the heap tuple now..
1337          *
1338          * ... but in POSTGRES, we have no need to do this because the vacuum
1339          * daemon automatically opens an index scan and deletes index tuples
1340          * when it finds deleted heap tuples. -cim 9/27/89
1341          */
1342
1343         /* AFTER ROW DELETE Triggers */
1344         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1345 }
1346
1347 /* ----------------------------------------------------------------
1348  *              ExecUpdate
1349  *
1350  *              note: we can't run UPDATE queries with transactions
1351  *              off because UPDATEs are actually INSERTs and our
1352  *              scan will mistakenly loop forever, updating the tuple
1353  *              it just inserted..      This should be fixed but until it
1354  *              is, we don't want to get stuck in an infinite loop
1355  *              which corrupts your database..
1356  * ----------------------------------------------------------------
1357  */
1358 static void
1359 ExecUpdate(TupleTableSlot *slot,
1360                    ItemPointer tupleid,
1361                    EState *estate)
1362 {
1363         HeapTuple       tuple;
1364         ResultRelInfo *resultRelInfo;
1365         Relation        resultRelationDesc;
1366         ItemPointerData ctid;
1367         int                     result;
1368         int                     numIndices;
1369
1370         /*
1371          * abort the operation if not running transactions
1372          */
1373         if (IsBootstrapProcessingMode())
1374         {
1375                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1376                 return;
1377         }
1378
1379         /*
1380          * get the heap tuple out of the tuple table slot
1381          */
1382         tuple = slot->val;
1383
1384         /*
1385          * get information on the (current) result relation
1386          */
1387         resultRelInfo = estate->es_result_relation_info;
1388         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1389
1390         /* BEFORE ROW UPDATE Triggers */
1391         if (resultRelInfo->ri_TrigDesc &&
1392           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1393         {
1394                 HeapTuple       newtuple;
1395
1396                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1397                                                                                 tupleid, tuple);
1398
1399                 if (newtuple == NULL)   /* "do nothing" */
1400                         return;
1401
1402                 if (newtuple != tuple)  /* modified by Trigger(s) */
1403                 {
1404                         /*
1405                          * Insert modified tuple into tuple table slot, replacing the
1406                          * original.  We assume that it was allocated in per-tuple
1407                          * memory context, and therefore will go away by itself. The
1408                          * tuple table slot should not try to clear it.
1409                          */
1410                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1411                         tuple = newtuple;
1412                 }
1413         }
1414
1415         /*
1416          * Check the constraints of the tuple
1417          *
1418          * If we generate a new candidate tuple after EvalPlanQual testing, we
1419          * must loop back here and recheck constraints.  (We don't need to
1420          * redo triggers, however.      If there are any BEFORE triggers then
1421          * trigger.c will have done mark4update to lock the correct tuple, so
1422          * there's no need to do them again.)
1423          */
1424 lreplace:;
1425         if (resultRelationDesc->rd_att->constr)
1426                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1427
1428         /*
1429          * replace the heap tuple
1430          */
1431         result = heap_update(resultRelationDesc, tupleid, tuple,
1432                                                  &ctid,
1433                                                  estate->es_snapshot->curcid);
1434         switch (result)
1435         {
1436                 case HeapTupleSelfUpdated:
1437                         /* already deleted by self; nothing to do */
1438                         return;
1439
1440                 case HeapTupleMayBeUpdated:
1441                         break;
1442
1443                 case HeapTupleUpdated:
1444                         if (XactIsoLevel == XACT_SERIALIZABLE)
1445                                 elog(ERROR, "Can't serialize access due to concurrent update");
1446                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1447                         {
1448                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1449                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1450
1451                                 if (!TupIsNull(epqslot))
1452                                 {
1453                                         *tupleid = ctid;
1454                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1455                                         slot = ExecStoreTuple(tuple,
1456                                                                         estate->es_junkFilter->jf_resultSlot,
1457                                                                                   InvalidBuffer, true);
1458                                         goto lreplace;
1459                                 }
1460                         }
1461                         /* tuple already deleted; nothing to do */
1462                         return;
1463
1464                 default:
1465                         elog(ERROR, "Unknown status %u from heap_update", result);
1466                         return;
1467         }
1468
1469         IncrReplaced();
1470         (estate->es_processed)++;
1471
1472         /*
1473          * Note: instead of having to update the old index tuples associated
1474          * with the heap tuple, all we do is form and insert new index tuples.
1475          * This is because UPDATEs are actually DELETEs and INSERTs and index
1476          * tuple deletion is done automagically by the vacuum daemon. All we
1477          * do is insert new index tuples.  -cim 9/27/89
1478          */
1479
1480         /*
1481          * process indices
1482          *
1483          * heap_update updates a tuple in the base relation by invalidating it
1484          * and then inserting a new tuple to the relation.      As a side effect,
1485          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1486          * field.  So we now insert index tuples using the new tupleid stored
1487          * there.
1488          */
1489
1490         numIndices = resultRelInfo->ri_NumIndices;
1491         if (numIndices > 0)
1492                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1493
1494         /* AFTER ROW UPDATE Triggers */
1495         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1496 }
1497
1498 static char *
1499 ExecRelCheck(ResultRelInfo *resultRelInfo,
1500                          TupleTableSlot *slot, EState *estate)
1501 {
1502         Relation        rel = resultRelInfo->ri_RelationDesc;
1503         int                     ncheck = rel->rd_att->constr->num_check;
1504         ConstrCheck *check = rel->rd_att->constr->check;
1505         ExprContext *econtext;
1506         MemoryContext oldContext;
1507         List       *qual;
1508         int                     i;
1509
1510         /*
1511          * If first time through for this result relation, build expression
1512          * nodetrees for rel's constraint expressions.  Keep them in the
1513          * per-query memory context so they'll survive throughout the query.
1514          */
1515         if (resultRelInfo->ri_ConstraintExprs == NULL)
1516         {
1517                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1518                 resultRelInfo->ri_ConstraintExprs =
1519                         (List **) palloc(ncheck * sizeof(List *));
1520                 for (i = 0; i < ncheck; i++)
1521                 {
1522                         qual = (List *) stringToNode(check[i].ccbin);
1523                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1524                                 ExecPrepareExpr((Expr *) qual, estate);
1525                 }
1526                 MemoryContextSwitchTo(oldContext);
1527         }
1528
1529         /*
1530          * We will use the EState's per-tuple context for evaluating
1531          * constraint expressions (creating it if it's not already there).
1532          */
1533         econtext = GetPerTupleExprContext(estate);
1534
1535         /* Arrange for econtext's scan tuple to be the tuple under test */
1536         econtext->ecxt_scantuple = slot;
1537
1538         /* And evaluate the constraints */
1539         for (i = 0; i < ncheck; i++)
1540         {
1541                 qual = resultRelInfo->ri_ConstraintExprs[i];
1542
1543                 /*
1544                  * NOTE: SQL92 specifies that a NULL result from a constraint
1545                  * expression is not to be treated as a failure.  Therefore, tell
1546                  * ExecQual to return TRUE for NULL.
1547                  */
1548                 if (!ExecQual(qual, econtext, true))
1549                         return check[i].ccname;
1550         }
1551
1552         /* NULL result means no error */
1553         return (char *) NULL;
1554 }
1555
1556 void
1557 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1558                                 TupleTableSlot *slot, EState *estate)
1559 {
1560         Relation        rel = resultRelInfo->ri_RelationDesc;
1561         HeapTuple       tuple = slot->val;
1562         TupleConstr *constr = rel->rd_att->constr;
1563
1564         Assert(constr);
1565
1566         if (constr->has_not_null)
1567         {
1568                 int                     natts = rel->rd_att->natts;
1569                 int                     attrChk;
1570
1571                 for (attrChk = 1; attrChk <= natts; attrChk++)
1572                 {
1573                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1574                                 heap_attisnull(tuple, attrChk))
1575                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1576                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1577                 }
1578         }
1579
1580         if (constr->num_check > 0)
1581         {
1582                 char       *failed;
1583
1584                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1585                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1586                                  caller, failed, RelationGetRelationName(rel));
1587         }
1588 }
1589
1590 /*
1591  * Check a modified tuple to see if we want to process its updated version
1592  * under READ COMMITTED rules.
1593  *
1594  * See backend/executor/README for some info about how this works.
1595  */
1596 TupleTableSlot *
1597 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1598 {
1599         evalPlanQual *epq;
1600         EState     *epqstate;
1601         Relation        relation;
1602         HeapTupleData tuple;
1603         HeapTuple       copyTuple = NULL;
1604         int                     rtsize;
1605         bool            endNode;
1606
1607         Assert(rti != 0);
1608
1609         /*
1610          * find relation containing target tuple
1611          */
1612         if (estate->es_result_relation_info != NULL &&
1613                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1614                 relation = estate->es_result_relation_info->ri_RelationDesc;
1615         else
1616         {
1617                 List       *l;
1618
1619                 relation = NULL;
1620                 foreach(l, estate->es_rowMark)
1621                 {
1622                         if (((execRowMark *) lfirst(l))->rti == rti)
1623                         {
1624                                 relation = ((execRowMark *) lfirst(l))->relation;
1625                                 break;
1626                         }
1627                 }
1628                 if (relation == NULL)
1629                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1630         }
1631
1632         /*
1633          * fetch tid tuple
1634          *
1635          * Loop here to deal with updated or busy tuples
1636          */
1637         tuple.t_self = *tid;
1638         for (;;)
1639         {
1640                 Buffer          buffer;
1641
1642                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1643                 {
1644                         TransactionId xwait = SnapshotDirty->xmax;
1645
1646                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1647                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1648
1649                         /*
1650                          * If tuple is being updated by other transaction then we have
1651                          * to wait for its commit/abort.
1652                          */
1653                         if (TransactionIdIsValid(xwait))
1654                         {
1655                                 ReleaseBuffer(buffer);
1656                                 XactLockTableWait(xwait);
1657                                 continue;
1658                         }
1659
1660                         /*
1661                          * We got tuple - now copy it for use by recheck query.
1662                          */
1663                         copyTuple = heap_copytuple(&tuple);
1664                         ReleaseBuffer(buffer);
1665                         break;
1666                 }
1667
1668                 /*
1669                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1670                  * Note that it's possible to get invalid SnapshotDirty->tid if
1671                  * tuple updated by this transaction. Have we to check this ?
1672                  */
1673                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1674                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1675                 {
1676                         /* updated, so look at the updated copy */
1677                         tuple.t_self = SnapshotDirty->tid;
1678                         continue;
1679                 }
1680
1681                 /*
1682                  * Deleted or updated by this transaction; forget it.
1683                  */
1684                 return NULL;
1685         }
1686
1687         /*
1688          * For UPDATE/DELETE we have to return tid of actual row we're
1689          * executing PQ for.
1690          */
1691         *tid = tuple.t_self;
1692
1693         /*
1694          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1695          */
1696         epq = (evalPlanQual *) estate->es_evalPlanQual;
1697         rtsize = length(estate->es_range_table);
1698         endNode = true;
1699
1700         if (epq != NULL && epq->rti == 0)
1701         {
1702                 /* Top PQ stack entry is idle, so re-use it */
1703                 Assert(!(estate->es_useEvalPlan) &&
1704                            epq->estate.es_evalPlanQual == NULL);
1705                 epq->rti = rti;
1706                 endNode = false;
1707         }
1708
1709         /*
1710          * If this is request for another RTE - Ra, - then we have to check
1711          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1712          * updated again and we have to re-start old execution for Ra and
1713          * forget all what we done after Ra was suspended. Cool? -:))
1714          */
1715         if (epq != NULL && epq->rti != rti &&
1716                 epq->estate.es_evTuple[rti - 1] != NULL)
1717         {
1718                 do
1719                 {
1720                         evalPlanQual *oldepq;
1721
1722                         /* pop previous PlanQual from the stack */
1723                         epqstate = &(epq->estate);
1724                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1725                         Assert(oldepq->rti != 0);
1726                         /* stop execution */
1727                         ExecEndNode(epq->planstate);
1728                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1729                         epqstate->es_tupleTable = NULL;
1730                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1731                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1732                         /* push current PQ to freePQ stack */
1733                         oldepq->free = epq;
1734                         epq = oldepq;
1735                         estate->es_evalPlanQual = (Pointer) epq;
1736                 } while (epq->rti != rti);
1737         }
1738
1739         /*
1740          * If we are requested for another RTE then we have to suspend
1741          * execution of current PlanQual and start execution for new one.
1742          */
1743         if (epq == NULL || epq->rti != rti)
1744         {
1745                 /* try to reuse plan used previously */
1746                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1747
1748                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1749                 {
1750                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1751                         newepq->free = NULL;
1752
1753                         /*
1754                          * Each stack level has its own copy of the plan tree.  This
1755                          * is wasteful, but necessary until plan trees are fully
1756                          * read-only.
1757                          */
1758                         newepq->plan = copyObject(estate->es_origPlan);
1759
1760                         /*
1761                          * Init stack level's EState.  We share top level's copy of
1762                          * es_result_relations array and other non-changing status. We
1763                          * need our own tupletable, es_param_exec_vals, and other
1764                          * changeable state.
1765                          */
1766                         epqstate = &(newepq->estate);
1767                         memcpy(epqstate, estate, sizeof(EState));
1768                         epqstate->es_direction = ForwardScanDirection;
1769                         if (estate->es_origPlan->nParamExec > 0)
1770                                 epqstate->es_param_exec_vals = (ParamExecData *)
1771                                         palloc(estate->es_origPlan->nParamExec *
1772                                                    sizeof(ParamExecData));
1773                         epqstate->es_tupleTable = NULL;
1774                         epqstate->es_per_tuple_exprcontext = NULL;
1775
1776                         /*
1777                          * Each epqstate must have its own es_evTupleNull state, but
1778                          * all the stack entries share es_evTuple state.  This allows
1779                          * sub-rechecks to inherit the value being examined by an
1780                          * outer recheck.
1781                          */
1782                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1783                         if (epq == NULL)
1784                                 /* first PQ stack entry */
1785                                 epqstate->es_evTuple = (HeapTuple *)
1786                                         palloc0(rtsize * sizeof(HeapTuple));
1787                         else
1788                                 /* later stack entries share the same storage */
1789                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1790                 }
1791                 else
1792                 {
1793                         /* recycle previously used EState */
1794                         epqstate = &(newepq->estate);
1795                 }
1796                 /* push current PQ to the stack */
1797                 epqstate->es_evalPlanQual = (Pointer) epq;
1798                 epq = newepq;
1799                 estate->es_evalPlanQual = (Pointer) epq;
1800                 epq->rti = rti;
1801                 endNode = false;
1802         }
1803
1804         Assert(epq->rti == rti);
1805         epqstate = &(epq->estate);
1806
1807         /*
1808          * Ok - we're requested for the same RTE.  Unfortunately we still have
1809          * to end and restart execution of the plan, because ExecReScan
1810          * wouldn't ensure that upper plan nodes would reset themselves.  We
1811          * could make that work if insertion of the target tuple were
1812          * integrated with the Param mechanism somehow, so that the upper plan
1813          * nodes know that their children's outputs have changed.
1814          */
1815         if (endNode)
1816         {
1817                 /* stop execution */
1818                 ExecEndNode(epq->planstate);
1819                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1820                 epqstate->es_tupleTable = NULL;
1821         }
1822
1823         /*
1824          * free old RTE' tuple, if any, and store target tuple where
1825          * relation's scan node will see it
1826          */
1827         if (epqstate->es_evTuple[rti - 1] != NULL)
1828                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1829         epqstate->es_evTuple[rti - 1] = copyTuple;
1830
1831         /*
1832          * Initialize for new recheck query; be careful to copy down state
1833          * that might have changed in top EState.
1834          */
1835         epqstate->es_result_relation_info = estate->es_result_relation_info;
1836         epqstate->es_junkFilter = estate->es_junkFilter;
1837         if (estate->es_origPlan->nParamExec > 0)
1838                 memset(epqstate->es_param_exec_vals, 0,
1839                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1840         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1841         epqstate->es_useEvalPlan = false;
1842         Assert(epqstate->es_tupleTable == NULL);
1843         epqstate->es_tupleTable =
1844                 ExecCreateTupleTable(estate->es_tupleTable->size);
1845
1846         epq->planstate = ExecInitNode(epq->plan, epqstate);
1847
1848         return EvalPlanQualNext(estate);
1849 }
1850
1851 static TupleTableSlot *
1852 EvalPlanQualNext(EState *estate)
1853 {
1854         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1855         EState     *epqstate = &(epq->estate);
1856         evalPlanQual *oldepq;
1857         TupleTableSlot *slot;
1858
1859         Assert(epq->rti != 0);
1860
1861 lpqnext:;
1862         slot = ExecProcNode(epq->planstate);
1863
1864         /*
1865          * No more tuples for this PQ. Continue previous one.
1866          */
1867         if (TupIsNull(slot))
1868         {
1869                 /* stop execution */
1870                 ExecEndNode(epq->planstate);
1871                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1872                 epqstate->es_tupleTable = NULL;
1873                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1874                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1875                 /* pop old PQ from the stack */
1876                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1877                 if (oldepq == (evalPlanQual *) NULL)
1878                 {
1879                         epq->rti = 0;           /* this is the first (oldest) */
1880                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1881                         return (NULL);          /* continue Query execution   */
1882                 }
1883                 Assert(oldepq->rti != 0);
1884                 /* push current PQ to freePQ stack */
1885                 oldepq->free = epq;
1886                 epq = oldepq;
1887                 epqstate = &(epq->estate);
1888                 estate->es_evalPlanQual = (Pointer) epq;
1889                 goto lpqnext;
1890         }
1891
1892         return (slot);
1893 }
1894
1895 static void
1896 EndEvalPlanQual(EState *estate)
1897 {
1898         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1899         EState     *epqstate = &(epq->estate);
1900         evalPlanQual *oldepq;
1901
1902         if (epq->rti == 0)                      /* plans already shutdowned */
1903         {
1904                 Assert(epq->estate.es_evalPlanQual == NULL);
1905                 return;
1906         }
1907
1908         for (;;)
1909         {
1910                 /* stop execution */
1911                 ExecEndNode(epq->planstate);
1912                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1913                 epqstate->es_tupleTable = NULL;
1914                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1915                 {
1916                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1917                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1918                 }
1919                 /* pop old PQ from the stack */
1920                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1921                 if (oldepq == (evalPlanQual *) NULL)
1922                 {
1923                         epq->rti = 0;           /* this is the first (oldest) */
1924                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1925                         break;
1926                 }
1927                 Assert(oldepq->rti != 0);
1928                 /* push current PQ to freePQ stack */
1929                 oldepq->free = epq;
1930                 epq = oldepq;
1931                 epqstate = &(epq->estate);
1932                 estate->es_evalPlanQual = (Pointer) epq;
1933         }
1934 }