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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.201 2003/03/10 03:53:49 tgl Exp $
  30  *
  31  *-------------------------------------------------------------------------
  32  */
  33 #include "postgres.h"
  34
  35 #include "access/heapam.h"
  36 #include "catalog/heap.h"
  37 #include "catalog/namespace.h"
  38 #include "commands/tablecmds.h"
  39 #include "commands/trigger.h"
  40 #include "executor/execdebug.h"
  41 #include "executor/execdefs.h"
  42 #include "miscadmin.h"
  43 #include "optimizer/var.h"
  44 #include "parser/parsetree.h"
  45 #include "utils/acl.h"
  46 #include "utils/lsyscache.h"
  47
  48
  49 typedef struct execRowMark
  50 {
  51         Relation        relation;
  52         Index           rti;
  53         char            resname[32];
  54 } execRowMark;
  55
  56 typedef struct evalPlanQual
  57 {
  58         Index           rti;
  59         EState     *estate;
  60         PlanState  *planstate;
  61         struct evalPlanQual *next;      /* stack of active PlanQual plans */
  62         struct evalPlanQual *free;      /* list of free PlanQual plans */
  63 } evalPlanQual;
  64
  65 /* decls for local routines only used within this module */
  66 static void InitPlan(QueryDesc *queryDesc);
  67 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  68                                   Index resultRelationIndex,
  69                                   List *rangeTable,
  70                                   CmdType operation);
  71 static TupleTableSlot *ExecutePlan(EState *estate, PlanState *planstate,
  72                         CmdType operation,
  73                         long numberTuples,
  74                         ScanDirection direction,
  75                         DestReceiver *destfunc);
  76 static void ExecSelect(TupleTableSlot *slot,
  77                    DestReceiver *destfunc,
  78                    EState *estate);
  79 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  80                    EState *estate);
  81 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  82                    EState *estate);
  83 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  84                    EState *estate);
  85 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  86 static void EndEvalPlanQual(EState *estate);
  87 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  88 static void ExecCheckXactReadOnly(Query *parsetree, CmdType operation);
  89 static void EvalPlanQualStart(evalPlanQual *epq, EState *estate,
  90                                                           evalPlanQual *priorepq);
  91 static void EvalPlanQualStop(evalPlanQual *epq);
  92
  93 /* end of local decls */
  94
  95
  96 /* ----------------------------------------------------------------
  97  *              ExecutorStart
  98  *
  99  *              This routine must be called at the beginning of any execution of any
 100  *              query plan
 101  *
 102  * Takes a QueryDesc previously created by CreateQueryDesc (it's not real
 103  * clear why we bother to separate the two functions, but...).  The tupDesc
 104  * field of the QueryDesc is filled in to describe the tuples that will be
 105  * returned, and the internal fields (estate and planstate) are set up.
 106  *
 107  * NB: the CurrentMemoryContext when this is called will become the parent
 108  * of the per-query context used for this Executor invocation.
 109  * ----------------------------------------------------------------
 110  */
 111 void
 112 ExecutorStart(QueryDesc *queryDesc)
 113 {
 114         EState     *estate;
 115         MemoryContext oldcontext;
 116
 117         /* sanity checks: queryDesc must not be started already */
 118         Assert(queryDesc != NULL);
 119         Assert(queryDesc->estate == NULL);
 120
 121         /*
 122          * Build EState, switch into per-query memory context for startup.
 123          */
 124         estate = CreateExecutorState();
 125         queryDesc->estate = estate;
 126
 127         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 128
 129         /*
 130          * Fill in parameters, if any, from queryDesc
 131          */
 132         estate->es_param_list_info = queryDesc->params;
 133
 134         if (queryDesc->plantree->nParamExec > 0)
 135                 estate->es_param_exec_vals = (ParamExecData *)
 136                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 137
 138         estate->es_instrument = queryDesc->doInstrument;
 139
 140         /*
 141          * Make our own private copy of the current query snapshot data.
 142          *
 143          * This "freezes" our idea of which tuples are good and which are not for
 144          * the life of this query, even if it outlives the current command and
 145          * current snapshot.
 146          */
 147         estate->es_snapshot = CopyQuerySnapshot();
 148
 149         /*
 150          * Initialize the plan state tree
 151          */
 152         InitPlan(queryDesc);
 153
 154         MemoryContextSwitchTo(oldcontext);
 155 }
 156
 157 /* ----------------------------------------------------------------
 158  *              ExecutorRun
 159  *
 160  *              This is the main routine of the executor module. It accepts
 161  *              the query descriptor from the traffic cop and executes the
 162  *              query plan.
 163  *
 164  *              ExecutorStart must have been called already.
 165  *
 166  *              If direction is NoMovementScanDirection then nothing is done
 167  *              except to start up/shut down the destination.  Otherwise,
 168  *              we retrieve up to 'count' tuples in the specified direction.
 169  *
 170  *              Note: count = 0 is interpreted as no portal limit, i.e., run to
 171  *              completion.
 172  *
 173  * ----------------------------------------------------------------
 174  */
 175 TupleTableSlot *
 176 ExecutorRun(QueryDesc *queryDesc,
 177                         ScanDirection direction, long count)
 178 {
 179         EState     *estate;
 180         CmdType         operation;
 181         CommandDest dest;
 182         DestReceiver *destfunc;
 183         TupleTableSlot *result;
 184         MemoryContext oldcontext;
 185
 186         /* sanity checks */
 187         Assert(queryDesc != NULL);
 188
 189         estate = queryDesc->estate;
 190
 191         Assert(estate != NULL);
 192
 193         /*
 194          * Switch into per-query memory context
 195          */
 196         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 197
 198         /*
 199          * extract information from the query descriptor and the query
 200          * feature.
 201          */
 202         operation = queryDesc->operation;
 203         dest = queryDesc->dest;
 204
 205         /*
 206          * If the transaction is read-only, we need to check if any writes
 207          * are planned to non-temporary tables.  This is done here at this
 208          * rather late stage so that we can handle EXPLAIN vs. EXPLAIN
 209          * ANALYZE easily.
 210          */
 211         ExecCheckXactReadOnly(queryDesc->parsetree, operation);
 212
 213         /*
 214          * startup tuple receiver
 215          */
 216         estate->es_processed = 0;
 217         estate->es_lastoid = InvalidOid;
 218
 219         destfunc = DestToFunction(dest);
 220         (*destfunc->setup) (destfunc, (int) operation,
 221                                                 queryDesc->portalName, queryDesc->tupDesc);
 222
 223         /*
 224          * run plan
 225          */
 226         if (direction == NoMovementScanDirection)
 227                 result = NULL;
 228         else
 229                 result = ExecutePlan(estate,
 230                                                          queryDesc->planstate,
 231                                                          operation,
 232                                                          count,
 233                                                          direction,
 234                                                          destfunc);
 235
 236         /*
 237          * shutdown receiver
 238          */
 239         (*destfunc->cleanup) (destfunc);
 240
 241         MemoryContextSwitchTo(oldcontext);
 242
 243         return result;
 244 }
 245
 246 /* ----------------------------------------------------------------
 247  *              ExecutorEnd
 248  *
 249  *              This routine must be called at the end of execution of any
 250  *              query plan
 251  * ----------------------------------------------------------------
 252  */
 253 void
 254 ExecutorEnd(QueryDesc *queryDesc)
 255 {
 256         EState     *estate;
 257         MemoryContext oldcontext;
 258
 259         /* sanity checks */
 260         Assert(queryDesc != NULL);
 261
 262         estate = queryDesc->estate;
 263
 264         Assert(estate != NULL);
 265
 266         /*
 267          * Switch into per-query memory context to run ExecEndPlan
 268          */
 269         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 270
 271         ExecEndPlan(queryDesc->planstate, estate);
 272
 273         /*
 274          * Must switch out of context before destroying it
 275          */
 276         MemoryContextSwitchTo(oldcontext);
 277
 278         /*
 279          * Release EState and per-query memory context.  This should release
 280          * everything the executor has allocated.
 281          */
 282         FreeExecutorState(estate);
 283
 284         /* Reset queryDesc fields that no longer point to anything */
 285         queryDesc->tupDesc = NULL;
 286         queryDesc->estate = NULL;
 287         queryDesc->planstate = NULL;
 288 }
 289
 290
 291 /*
 292  * ExecCheckRTPerms
 293  *              Check access permissions for all relations listed in a range table.
 294  */
 295 void
 296 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 297 {
 298         List       *lp;
 299
 300         foreach(lp, rangeTable)
 301         {
 302                 RangeTblEntry *rte = lfirst(lp);
 303
 304                 ExecCheckRTEPerms(rte, operation);
 305         }
 306 }
 307
 308 /*
 309  * ExecCheckRTEPerms
 310  *              Check access permissions for a single RTE.
 311  */
 312 static void
 313 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 314 {
 315         Oid                     relOid;
 316         AclId           userid;
 317         AclResult       aclcheck_result;
 318
 319         /*
 320          * If it's a subquery, recursively examine its rangetable.
 321          */
 322         if (rte->rtekind == RTE_SUBQUERY)
 323         {
 324                 ExecCheckRTPerms(rte->subquery->rtable, operation);
 325                 return;
 326         }
 327
 328         /*
 329          * Otherwise, only plain-relation RTEs need to be checked here.
 330          * Function RTEs are checked by init_fcache when the function is prepared
 331          * for execution. Join and special RTEs need no checks.
 332          */
 333         if (rte->rtekind != RTE_RELATION)
 334                 return;
 335
 336         relOid = rte->relid;
 337
 338         /*
 339          * userid to check as: current user unless we have a setuid
 340          * indication.
 341          *
 342          * Note: GetUserId() is presently fast enough that there's no harm in
 343          * calling it separately for each RTE.  If that stops being true, we
 344          * could call it once in ExecCheckRTPerms and pass the userid down
 345          * from there.  But for now, no need for the extra clutter.
 346          */
 347         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 348
 349 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 350
 351         if (rte->checkForRead)
 352         {
 353                 aclcheck_result = CHECK(ACL_SELECT);
 354                 if (aclcheck_result != ACLCHECK_OK)
 355                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 356         }
 357
 358         if (rte->checkForWrite)
 359         {
 360                 /*
 361                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 362                  * Right now we don't distinguish that from true update as far as
 363                  * permissions checks are concerned.
 364                  */
 365                 switch (operation)
 366                 {
 367                         case CMD_INSERT:
 368                                 aclcheck_result = CHECK(ACL_INSERT);
 369                                 break;
 370                         case CMD_SELECT:
 371                         case CMD_UPDATE:
 372                                 aclcheck_result = CHECK(ACL_UPDATE);
 373                                 break;
 374                         case CMD_DELETE:
 375                                 aclcheck_result = CHECK(ACL_DELETE);
 376                                 break;
 377                         default:
 378                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 379                                          operation);
 380                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 381                                 break;
 382                 }
 383                 if (aclcheck_result != ACLCHECK_OK)
 384                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 385         }
 386 }
 387
 388
 389 /* ===============================================================
 390  * ===============================================================
 391                                                  static routines follow
 392  * ===============================================================
 393  * ===============================================================
 394  */
 395
 396
 397 static void
 398 ExecCheckXactReadOnly(Query *parsetree, CmdType operation)
 399 {
 400         if (!XactReadOnly)
 401                 return;
 402
 403         /* CREATE TABLE AS or SELECT INTO */
 404         if (operation == CMD_SELECT && parsetree->into != NULL)
 405                 goto fail;
 406
 407         if (operation == CMD_DELETE || operation == CMD_INSERT
 408                 || operation == CMD_UPDATE)
 409         {
 410                 List *lp;
 411
 412                 foreach(lp, parsetree->rtable)
 413                 {
 414                         RangeTblEntry *rte = lfirst(lp);
 415
 416                         if (rte->rtekind != RTE_RELATION)
 417                                 continue;
 418
 419                         if (!rte->checkForWrite)
 420                                 continue;
 421
 422                         if (isTempNamespace(get_rel_namespace(rte->relid)))
 423                                 continue;
 424
 425                         goto fail;
 426                 }
 427         }
 428
 429         return;
 430
 431 fail:
 432         elog(ERROR, "transaction is read-only");
 433 }
 434
 435
 436 /* ----------------------------------------------------------------
 437  *              InitPlan
 438  *
 439  *              Initializes the query plan: open files, allocate storage
 440  *              and start up the rule manager
 441  * ----------------------------------------------------------------
 442  */
 443 static void
 444 InitPlan(QueryDesc *queryDesc)
 445 {
 446         CmdType         operation = queryDesc->operation;
 447         Query *parseTree = queryDesc->parsetree;
 448         Plan *plan = queryDesc->plantree;
 449         EState *estate = queryDesc->estate;
 450         PlanState  *planstate;
 451         List       *rangeTable;
 452         Relation        intoRelationDesc;
 453         bool            do_select_into;
 454         TupleDesc       tupType;
 455
 456         /*
 457          * Do permissions checks.  It's sufficient to examine the query's
 458          * top rangetable here --- subplan RTEs will be checked during
 459          * ExecInitSubPlan().
 460          */
 461         ExecCheckRTPerms(parseTree->rtable, operation);
 462
 463         /*
 464          * get information from query descriptor
 465          */
 466         rangeTable = parseTree->rtable;
 467
 468         /*
 469          * initialize the node's execution state
 470          */
 471         estate->es_range_table = rangeTable;
 472
 473         /*
 474          * if there is a result relation, initialize result relation stuff
 475          */
 476         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 477         {
 478                 List       *resultRelations = parseTree->resultRelations;
 479                 int                     numResultRelations;
 480                 ResultRelInfo *resultRelInfos;
 481
 482                 if (resultRelations != NIL)
 483                 {
 484                         /*
 485                          * Multiple result relations (due to inheritance)
 486                          * parseTree->resultRelations identifies them all
 487                          */
 488                         ResultRelInfo *resultRelInfo;
 489
 490                         numResultRelations = length(resultRelations);
 491                         resultRelInfos = (ResultRelInfo *)
 492                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 493                         resultRelInfo = resultRelInfos;
 494                         while (resultRelations != NIL)
 495                         {
 496                                 initResultRelInfo(resultRelInfo,
 497                                                                   lfirsti(resultRelations),
 498                                                                   rangeTable,
 499                                                                   operation);
 500                                 resultRelInfo++;
 501                                 resultRelations = lnext(resultRelations);
 502                         }
 503                 }
 504                 else
 505                 {
 506                         /*
 507                          * Single result relation identified by
 508                          * parseTree->resultRelation
 509                          */
 510                         numResultRelations = 1;
 511                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 512                         initResultRelInfo(resultRelInfos,
 513                                                           parseTree->resultRelation,
 514                                                           rangeTable,
 515                                                           operation);
 516                 }
 517
 518                 estate->es_result_relations = resultRelInfos;
 519                 estate->es_num_result_relations = numResultRelations;
 520                 /* Initialize to first or only result rel */
 521                 estate->es_result_relation_info = resultRelInfos;
 522         }
 523         else
 524         {
 525                 /*
 526                  * if no result relation, then set state appropriately
 527                  */
 528                 estate->es_result_relations = NULL;
 529                 estate->es_num_result_relations = 0;
 530                 estate->es_result_relation_info = NULL;
 531         }
 532
 533         /*
 534          * Detect whether we're doing SELECT INTO.  If so, set the force_oids
 535          * flag appropriately so that the plan tree will be initialized with
 536          * the correct tuple descriptors.
 537          */
 538         do_select_into = false;
 539
 540         if (operation == CMD_SELECT && parseTree->into != NULL)
 541         {
 542                 do_select_into = true;
 543                 /*
 544                  * For now, always create OIDs in SELECT INTO; this is for backwards
 545                  * compatibility with pre-7.3 behavior.  Eventually we might want
 546                  * to allow the user to choose.
 547                  */
 548                 estate->es_force_oids = true;
 549         }
 550
 551         /*
 552          * Have to lock relations selected for update
 553          */
 554         estate->es_rowMark = NIL;
 555         if (parseTree->rowMarks != NIL)
 556         {
 557                 List       *l;
 558
 559                 foreach(l, parseTree->rowMarks)
 560                 {
 561                         Index           rti = lfirsti(l);
 562                         Oid                     relid = getrelid(rti, rangeTable);
 563                         Relation        relation;
 564                         execRowMark *erm;
 565
 566                         relation = heap_open(relid, RowShareLock);
 567                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 568                         erm->relation = relation;
 569                         erm->rti = rti;
 570                         snprintf(erm->resname, 32, "ctid%u", rti);
 571                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 572                 }
 573         }
 574
 575         /*
 576          * initialize the executor "tuple" table.  We need slots for all the
 577          * plan nodes, plus possibly output slots for the junkfilter(s). At
 578          * this point we aren't sure if we need junkfilters, so just add slots
 579          * for them unconditionally.
 580          */
 581         {
 582                 int                     nSlots = ExecCountSlotsNode(plan);
 583
 584                 if (parseTree->resultRelations != NIL)
 585                         nSlots += length(parseTree->resultRelations);
 586                 else
 587                         nSlots += 1;
 588                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 589         }
 590
 591         /* mark EvalPlanQual not active */
 592         estate->es_topPlan = plan;
 593         estate->es_evalPlanQual = NULL;
 594         estate->es_evTupleNull = NULL;
 595         estate->es_evTuple = NULL;
 596         estate->es_useEvalPlan = false;
 597
 598         /*
 599          * initialize the private state information for all the nodes in the
 600          * query tree.  This opens files, allocates storage and leaves us
 601          * ready to start processing tuples.
 602          */
 603         planstate = ExecInitNode(plan, estate);
 604
 605         /*
 606          * Get the tuple descriptor describing the type of tuples to return.
 607          * (this is especially important if we are creating a relation with
 608          * "SELECT INTO")
 609          */
 610         tupType = ExecGetTupType(planstate);
 611
 612         /*
 613          * Initialize the junk filter if needed.  SELECT and INSERT queries need a
 614          * filter if there are any junk attrs in the tlist.  INSERT and SELECT
 615          * INTO also need a filter if the top plan node is a scan node that's not
 616          * doing projection (else we'll be scribbling on the scan tuple!)  UPDATE
 617          * and DELETE always need a filter, since there's always a junk 'ctid'
 618          * attribute present --- no need to look first.
 619          */
 620         {
 621                 bool            junk_filter_needed = false;
 622                 List       *tlist;
 623
 624                 switch (operation)
 625                 {
 626                         case CMD_SELECT:
 627                         case CMD_INSERT:
 628                                 foreach(tlist, plan->targetlist)
 629                                 {
 630                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 631
 632                                         if (tle->resdom->resjunk)
 633                                         {
 634                                                 junk_filter_needed = true;
 635                                                 break;
 636                                         }
 637                                 }
 638                                 if (!junk_filter_needed &&
 639                                         (operation == CMD_INSERT || do_select_into))
 640                                 {
 641                                         if (IsA(planstate, SeqScanState) ||
 642                                                 IsA(planstate, IndexScanState) ||
 643                                                 IsA(planstate, TidScanState) ||
 644                                                 IsA(planstate, SubqueryScanState) ||
 645                                                 IsA(planstate, FunctionScanState))
 646                                         {
 647                                                 if (planstate->ps_ProjInfo == NULL)
 648                                                         junk_filter_needed = true;
 649                                         }
 650                                 }
 651                                 break;
 652                         case CMD_UPDATE:
 653                         case CMD_DELETE:
 654                                 junk_filter_needed = true;
 655                                 break;
 656                         default:
 657                                 break;
 658                 }
 659
 660                 if (junk_filter_needed)
 661                 {
 662                         /*
 663                          * If there are multiple result relations, each one needs its
 664                          * own junk filter.  Note this is only possible for
 665                          * UPDATE/DELETE, so we can't be fooled by some needing a
 666                          * filter and some not.
 667                          */
 668                         if (parseTree->resultRelations != NIL)
 669                         {
 670                                 PlanState **appendplans;
 671                                 int                     as_nplans;
 672                                 ResultRelInfo *resultRelInfo;
 673                                 int                     i;
 674
 675                                 /* Top plan had better be an Append here. */
 676                                 Assert(IsA(plan, Append));
 677                                 Assert(((Append *) plan)->isTarget);
 678                                 Assert(IsA(planstate, AppendState));
 679                                 appendplans = ((AppendState *) planstate)->appendplans;
 680                                 as_nplans = ((AppendState *) planstate)->as_nplans;
 681                                 Assert(as_nplans == estate->es_num_result_relations);
 682                                 resultRelInfo = estate->es_result_relations;
 683                                 for (i = 0; i < as_nplans; i++)
 684                                 {
 685                                         PlanState  *subplan = appendplans[i];
 686                                         JunkFilter *j;
 687
 688                                         j = ExecInitJunkFilter(subplan->plan->targetlist,
 689                                                                                    ExecGetTupType(subplan),
 690                                                           ExecAllocTableSlot(estate->es_tupleTable));
 691                                         resultRelInfo->ri_junkFilter = j;
 692                                         resultRelInfo++;
 693                                 }
 694
 695                                 /*
 696                                  * Set active junkfilter too; at this point ExecInitAppend
 697                                  * has already selected an active result relation...
 698                                  */
 699                                 estate->es_junkFilter =
 700                                         estate->es_result_relation_info->ri_junkFilter;
 701                         }
 702                         else
 703                         {
 704                                 /* Normal case with just one JunkFilter */
 705                                 JunkFilter *j;
 706
 707                                 j = ExecInitJunkFilter(planstate->plan->targetlist,
 708                                                                            tupType,
 709                                                           ExecAllocTableSlot(estate->es_tupleTable));
 710                                 estate->es_junkFilter = j;
 711                                 if (estate->es_result_relation_info)
 712                                         estate->es_result_relation_info->ri_junkFilter = j;
 713
 714                                 /* For SELECT, want to return the cleaned tuple type */
 715                                 if (operation == CMD_SELECT)
 716                                         tupType = j->jf_cleanTupType;
 717                         }
 718                 }
 719                 else
 720                         estate->es_junkFilter = NULL;
 721         }
 722
 723         /*
 724          * If doing SELECT INTO, initialize the "into" relation.  We must wait
 725          * till now so we have the "clean" result tuple type to create the
 726          * new table from.
 727          */
 728         intoRelationDesc = (Relation) NULL;
 729
 730         if (do_select_into)
 731         {
 732                 char       *intoName;
 733                 Oid                     namespaceId;
 734                 AclResult       aclresult;
 735                 Oid                     intoRelationId;
 736                 TupleDesc       tupdesc;
 737
 738                 /*
 739                  * find namespace to create in, check permissions
 740                  */
 741                 intoName = parseTree->into->relname;
 742                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 743
 744                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 745                                                                                   ACL_CREATE);
 746                 if (aclresult != ACLCHECK_OK)
 747                         aclcheck_error(aclresult, get_namespace_name(namespaceId));
 748
 749                 /*
 750                  * have to copy tupType to get rid of constraints
 751                  */
 752                 tupdesc = CreateTupleDescCopy(tupType);
 753
 754                 intoRelationId = heap_create_with_catalog(intoName,
 755                                                                                                   namespaceId,
 756                                                                                                   tupdesc,
 757                                                                                                   RELKIND_RELATION,
 758                                                                                                   false,
 759                                                                                                   ONCOMMIT_NOOP,
 760                                                                                                   allowSystemTableMods);
 761
 762                 FreeTupleDesc(tupdesc);
 763
 764                 /*
 765                  * Advance command counter so that the newly-created
 766                  * relation's catalog tuples will be visible to heap_open.
 767                  */
 768                 CommandCounterIncrement();
 769
 770                 /*
 771                  * If necessary, create a TOAST table for the into
 772                  * relation. Note that AlterTableCreateToastTable ends
 773                  * with CommandCounterIncrement(), so that the TOAST table
 774                  * will be visible for insertion.
 775                  */
 776                 AlterTableCreateToastTable(intoRelationId, true);
 777
 778                 /*
 779                  * And open the constructed table for writing.
 780                  */
 781                 intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock);
 782         }
 783
 784         estate->es_into_relation_descriptor = intoRelationDesc;
 785
 786         queryDesc->tupDesc = tupType;
 787         queryDesc->planstate = planstate;
 788 }
 789
 790 /*
 791  * Initialize ResultRelInfo data for one result relation
 792  */
 793 static void
 794 initResultRelInfo(ResultRelInfo *resultRelInfo,
 795                                   Index resultRelationIndex,
 796                                   List *rangeTable,
 797                                   CmdType operation)
 798 {
 799         Oid                     resultRelationOid;
 800         Relation        resultRelationDesc;
 801
 802         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 803         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 804
 805         switch (resultRelationDesc->rd_rel->relkind)
 806         {
 807                 case RELKIND_SEQUENCE:
 808                         elog(ERROR, "You can't change sequence relation %s",
 809                                  RelationGetRelationName(resultRelationDesc));
 810                         break;
 811                 case RELKIND_TOASTVALUE:
 812                         elog(ERROR, "You can't change toast relation %s",
 813                                  RelationGetRelationName(resultRelationDesc));
 814                         break;
 815                 case RELKIND_VIEW:
 816                         elog(ERROR, "You can't change view relation %s",
 817                                  RelationGetRelationName(resultRelationDesc));
 818                         break;
 819         }
 820
 821         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 822         resultRelInfo->type = T_ResultRelInfo;
 823         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 824         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 825         resultRelInfo->ri_NumIndices = 0;
 826         resultRelInfo->ri_IndexRelationDescs = NULL;
 827         resultRelInfo->ri_IndexRelationInfo = NULL;
 828         /* make a copy so as not to depend on relcache info not changing... */
 829         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 830         resultRelInfo->ri_TrigFunctions = NULL;
 831         resultRelInfo->ri_ConstraintExprs = NULL;
 832         resultRelInfo->ri_junkFilter = NULL;
 833
 834         /*
 835          * If there are indices on the result relation, open them and save
 836          * descriptors in the result relation info, so that we can add new
 837          * index entries for the tuples we add/update.  We need not do this
 838          * for a DELETE, however, since deletion doesn't affect indexes.
 839          */
 840         if (resultRelationDesc->rd_rel->relhasindex &&
 841                 operation != CMD_DELETE)
 842                 ExecOpenIndices(resultRelInfo);
 843 }
 844
 845 /* ----------------------------------------------------------------
 846  *              ExecEndPlan
 847  *
 848  *              Cleans up the query plan -- closes files and frees up storage
 849  *
 850  * NOTE: we are no longer very worried about freeing storage per se
 851  * in this code; FreeExecutorState should be guaranteed to release all
 852  * memory that needs to be released.  What we are worried about doing
 853  * is closing relations and dropping buffer pins.  Thus, for example,
 854  * tuple tables must be cleared or dropped to ensure pins are released.
 855  * ----------------------------------------------------------------
 856  */
 857 void
 858 ExecEndPlan(PlanState *planstate, EState *estate)
 859 {
 860         ResultRelInfo *resultRelInfo;
 861         int                     i;
 862         List       *l;
 863
 864         /*
 865          * shut down any PlanQual processing we were doing
 866          */
 867         if (estate->es_evalPlanQual != NULL)
 868                 EndEvalPlanQual(estate);
 869
 870         /*
 871          * shut down the node-type-specific query processing
 872          */
 873         ExecEndNode(planstate);
 874
 875         /*
 876          * destroy the executor "tuple" table.
 877          */
 878         ExecDropTupleTable(estate->es_tupleTable, true);
 879         estate->es_tupleTable = NULL;
 880
 881         /*
 882          * close the result relation(s) if any, but hold locks until xact
 883          * commit.
 884          */
 885         resultRelInfo = estate->es_result_relations;
 886         for (i = estate->es_num_result_relations; i > 0; i--)
 887         {
 888                 /* Close indices and then the relation itself */
 889                 ExecCloseIndices(resultRelInfo);
 890                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 891                 resultRelInfo++;
 892         }
 893
 894         /*
 895          * close the "into" relation if necessary, again keeping lock
 896          */
 897         if (estate->es_into_relation_descriptor != NULL)
 898                 heap_close(estate->es_into_relation_descriptor, NoLock);
 899
 900         /*
 901          * close any relations selected FOR UPDATE, again keeping locks
 902          */
 903         foreach(l, estate->es_rowMark)
 904         {
 905                 execRowMark *erm = lfirst(l);
 906
 907                 heap_close(erm->relation, NoLock);
 908         }
 909 }
 910
 911 /* ----------------------------------------------------------------
 912  *              ExecutePlan
 913  *
 914  *              processes the query plan to retrieve 'numberTuples' tuples in the
 915  *              direction specified.
 916  *
 917  *              Retrieves all tuples if numberTuples is 0
 918  *
 919  *              result is either a slot containing the last tuple in the case
 920  *              of a SELECT or NULL otherwise.
 921  *
 922  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 923  * user can see it
 924  * ----------------------------------------------------------------
 925  */
 926 static TupleTableSlot *
 927 ExecutePlan(EState *estate,
 928                         PlanState *planstate,
 929                         CmdType operation,
 930                         long numberTuples,
 931                         ScanDirection direction,
 932                         DestReceiver *destfunc)
 933 {
 934         JunkFilter                      *junkfilter;
 935         TupleTableSlot          *slot;
 936         ItemPointer                      tupleid = NULL;
 937         ItemPointerData          tuple_ctid;
 938         long                             current_tuple_count;
 939         TupleTableSlot          *result;
 940
 941         /*
 942          * initialize local variables
 943          */
 944         slot = NULL;
 945         current_tuple_count = 0;
 946         result = NULL;
 947
 948         /*
 949          * Set the direction.
 950          */
 951         estate->es_direction = direction;
 952
 953         /*
 954          * Process BEFORE EACH STATEMENT triggers
 955          */
 956         switch (operation)
 957         {
 958                 case CMD_UPDATE:
 959                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 960                         break;
 961                 case CMD_DELETE:
 962                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 963                         break;
 964                 case CMD_INSERT:
 965                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 966                         break;
 967                 default:
 968                         /* do nothing */
 969                         break;
 970         }
 971
 972         /*
 973          * Loop until we've processed the proper number of tuples from the
 974          * plan.
 975          */
 976
 977         for (;;)
 978         {
 979                 /* Reset the per-output-tuple exprcontext */
 980                 ResetPerTupleExprContext(estate);
 981
 982                 /*
 983                  * Execute the plan and obtain a tuple
 984                  */
 985 lnext:  ;
 986                 if (estate->es_useEvalPlan)
 987                 {
 988                         slot = EvalPlanQualNext(estate);
 989                         if (TupIsNull(slot))
 990                                 slot = ExecProcNode(planstate);
 991                 }
 992                 else
 993                         slot = ExecProcNode(planstate);
 994
 995                 /*
 996                  * if the tuple is null, then we assume there is nothing more to
 997                  * process so we just return null...
 998                  */
 999                 if (TupIsNull(slot))
1000                 {
1001                         result = NULL;
1002                         break;
1003                 }
1004
1005                 /*
1006                  * if we have a junk filter, then project a new tuple with the
1007                  * junk removed.
1008                  *
1009                  * Store this new "clean" tuple in the junkfilter's resultSlot.
1010                  * (Formerly, we stored it back over the "dirty" tuple, which is
1011                  * WRONG because that tuple slot has the wrong descriptor.)
1012                  *
1013                  * Also, extract all the junk information we need.
1014                  */
1015                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
1016                 {
1017                         Datum           datum;
1018                         HeapTuple       newTuple;
1019                         bool            isNull;
1020
1021                         /*
1022                          * extract the 'ctid' junk attribute.
1023                          */
1024                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1025                         {
1026                                 if (!ExecGetJunkAttribute(junkfilter,
1027                                                                                   slot,
1028                                                                                   "ctid",
1029                                                                                   &datum,
1030                                                                                   &isNull))
1031                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1032
1033                                 /* shouldn't ever get a null result... */
1034                                 if (isNull)
1035                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1036
1037                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1038                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1039                                                                                  * ctid!! */
1040                                 tupleid = &tuple_ctid;
1041                         }
1042                         else if (estate->es_rowMark != NIL)
1043                         {
1044                                 List       *l;
1045
1046                 lmark:  ;
1047                                 foreach(l, estate->es_rowMark)
1048                                 {
1049                                         execRowMark *erm = lfirst(l);
1050                                         Buffer          buffer;
1051                                         HeapTupleData tuple;
1052                                         TupleTableSlot *newSlot;
1053                                         int                     test;
1054
1055                                         if (!ExecGetJunkAttribute(junkfilter,
1056                                                                                           slot,
1057                                                                                           erm->resname,
1058                                                                                           &datum,
1059                                                                                           &isNull))
1060                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1061                                                          erm->resname);
1062
1063                                         /* shouldn't ever get a null result... */
1064                                         if (isNull)
1065                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1066                                                          erm->resname);
1067
1068                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1069                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1070                                                                                         estate->es_snapshot->curcid);
1071                                         ReleaseBuffer(buffer);
1072                                         switch (test)
1073                                         {
1074                                                 case HeapTupleSelfUpdated:
1075                                                         /* treat it as deleted; do not process */
1076                                                         goto lnext;
1077
1078                                                 case HeapTupleMayBeUpdated:
1079                                                         break;
1080
1081                                                 case HeapTupleUpdated:
1082                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1083                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1084                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1085                                                                   (ItemPointer) DatumGetPointer(datum))))
1086                                                         {
1087                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1088                                                                 if (!(TupIsNull(newSlot)))
1089                                                                 {
1090                                                                         slot = newSlot;
1091                                                                         estate->es_useEvalPlan = true;
1092                                                                         goto lmark;
1093                                                                 }
1094                                                         }
1095
1096                                                         /*
1097                                                          * if tuple was deleted or PlanQual failed for
1098                                                          * updated tuple - we must not return this
1099                                                          * tuple!
1100                                                          */
1101                                                         goto lnext;
1102
1103                                                 default:
1104                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1105                                                         return (NULL);
1106                                         }
1107                                 }
1108                         }
1109
1110                         /*
1111                          * Finally create a new "clean" tuple with all junk attributes
1112                          * removed
1113                          */
1114                         newTuple = ExecRemoveJunk(junkfilter, slot);
1115
1116                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1117                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1118                                                                   InvalidBuffer,                /* this tuple has no
1119                                                                                                                  * buffer */
1120                                                                   true);                /* tuple should be pfreed */
1121                 }
1122
1123                 /*
1124                  * now that we have a tuple, do the appropriate thing with it..
1125                  * either return it to the user, add it to a relation someplace,
1126                  * delete it from a relation, or modify some of its attributes.
1127                  */
1128                 switch (operation)
1129                 {
1130                         case CMD_SELECT:
1131                                 ExecSelect(slot,        /* slot containing tuple */
1132                                                    destfunc,    /* destination's tuple-receiver
1133                                                                                  * obj */
1134                                                    estate);
1135                                 result = slot;
1136                                 break;
1137
1138                         case CMD_INSERT:
1139                                 ExecInsert(slot, tupleid, estate);
1140                                 result = NULL;
1141                                 break;
1142
1143                         case CMD_DELETE:
1144                                 ExecDelete(slot, tupleid, estate);
1145                                 result = NULL;
1146                                 break;
1147
1148                         case CMD_UPDATE:
1149                                 ExecUpdate(slot, tupleid, estate);
1150                                 result = NULL;
1151                                 break;
1152
1153                         default:
1154                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1155                                 result = NULL;
1156                                 break;
1157                 }
1158
1159                 /*
1160                  * check our tuple count.. if we've processed the proper number
1161                  * then quit, else loop again and process more tuples.  Zero
1162                  * numberTuples means no limit.
1163                  */
1164                 current_tuple_count++;
1165                 if (numberTuples && numberTuples == current_tuple_count)
1166                         break;
1167         }
1168
1169         /*
1170          * Process AFTER EACH STATEMENT triggers
1171          */
1172         switch (operation)
1173         {
1174                 case CMD_UPDATE:
1175                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1176                         break;
1177                 case CMD_DELETE:
1178                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1179                         break;
1180                 case CMD_INSERT:
1181                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1182                         break;
1183                 default:
1184                         /* do nothing */
1185                         break;
1186         }
1187
1188         /*
1189          * here, result is either a slot containing a tuple in the case of a
1190          * SELECT or NULL otherwise.
1191          */
1192         return result;
1193 }
1194
1195 /* ----------------------------------------------------------------
1196  *              ExecSelect
1197  *
1198  *              SELECTs are easy.. we just pass the tuple to the appropriate
1199  *              print function.  The only complexity is when we do a
1200  *              "SELECT INTO", in which case we insert the tuple into
1201  *              the appropriate relation (note: this is a newly created relation
1202  *              so we don't need to worry about indices or locks.)
1203  * ----------------------------------------------------------------
1204  */
1205 static void
1206 ExecSelect(TupleTableSlot *slot,
1207                    DestReceiver *destfunc,
1208                    EState *estate)
1209 {
1210         HeapTuple       tuple;
1211         TupleDesc       attrtype;
1212
1213         /*
1214          * get the heap tuple out of the tuple table slot
1215          */
1216         tuple = slot->val;
1217         attrtype = slot->ttc_tupleDescriptor;
1218
1219         /*
1220          * insert the tuple into the "into relation"
1221          */
1222         if (estate->es_into_relation_descriptor != NULL)
1223         {
1224                 heap_insert(estate->es_into_relation_descriptor, tuple,
1225                                         estate->es_snapshot->curcid);
1226                 IncrAppended();
1227         }
1228
1229         /*
1230          * send the tuple to the front end (or the screen)
1231          */
1232         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1233         IncrRetrieved();
1234         (estate->es_processed)++;
1235 }
1236
1237 /* ----------------------------------------------------------------
1238  *              ExecInsert
1239  *
1240  *              INSERTs are trickier.. we have to insert the tuple into
1241  *              the base relation and insert appropriate tuples into the
1242  *              index relations.
1243  * ----------------------------------------------------------------
1244  */
1245 static void
1246 ExecInsert(TupleTableSlot *slot,
1247                    ItemPointer tupleid,
1248                    EState *estate)
1249 {
1250         HeapTuple       tuple;
1251         ResultRelInfo *resultRelInfo;
1252         Relation        resultRelationDesc;
1253         int                     numIndices;
1254         Oid                     newId;
1255
1256         /*
1257          * get the heap tuple out of the tuple table slot
1258          */
1259         tuple = slot->val;
1260
1261         /*
1262          * get information on the (current) result relation
1263          */
1264         resultRelInfo = estate->es_result_relation_info;
1265         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1266
1267         /* BEFORE ROW INSERT Triggers */
1268         if (resultRelInfo->ri_TrigDesc &&
1269                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1270         {
1271                 HeapTuple       newtuple;
1272
1273                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1274
1275                 if (newtuple == NULL)   /* "do nothing" */
1276                         return;
1277
1278                 if (newtuple != tuple)  /* modified by Trigger(s) */
1279                 {
1280                         /*
1281                          * Insert modified tuple into tuple table slot, replacing the
1282                          * original.  We assume that it was allocated in per-tuple
1283                          * memory context, and therefore will go away by itself. The
1284                          * tuple table slot should not try to clear it.
1285                          */
1286                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1287                         tuple = newtuple;
1288                 }
1289         }
1290
1291         /*
1292          * Check the constraints of the tuple
1293          */
1294         if (resultRelationDesc->rd_att->constr)
1295                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1296
1297         /*
1298          * insert the tuple
1299          */
1300         newId = heap_insert(resultRelationDesc, tuple,
1301                                                 estate->es_snapshot->curcid);
1302
1303         IncrAppended();
1304         (estate->es_processed)++;
1305         estate->es_lastoid = newId;
1306         setLastTid(&(tuple->t_self));
1307
1308         /*
1309          * process indices
1310          *
1311          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1312          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1313          * field.
1314          */
1315         numIndices = resultRelInfo->ri_NumIndices;
1316         if (numIndices > 0)
1317                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1318
1319         /* AFTER ROW INSERT Triggers */
1320         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1321 }
1322
1323 /* ----------------------------------------------------------------
1324  *              ExecDelete
1325  *
1326  *              DELETE is like UPDATE, we delete the tuple and its
1327  *              index tuples.
1328  * ----------------------------------------------------------------
1329  */
1330 static void
1331 ExecDelete(TupleTableSlot *slot,
1332                    ItemPointer tupleid,
1333                    EState *estate)
1334 {
1335         ResultRelInfo *resultRelInfo;
1336         Relation        resultRelationDesc;
1337         ItemPointerData ctid;
1338         int                     result;
1339
1340         /*
1341          * get information on the (current) result relation
1342          */
1343         resultRelInfo = estate->es_result_relation_info;
1344         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1345
1346         /* BEFORE ROW DELETE Triggers */
1347         if (resultRelInfo->ri_TrigDesc &&
1348           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1349         {
1350                 bool            dodelete;
1351
1352                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1353
1354                 if (!dodelete)                  /* "do nothing" */
1355                         return;
1356         }
1357
1358         /*
1359          * delete the tuple
1360          */
1361 ldelete:;
1362         result = heap_delete(resultRelationDesc, tupleid,
1363                                                  &ctid,
1364                                                  estate->es_snapshot->curcid);
1365         switch (result)
1366         {
1367                 case HeapTupleSelfUpdated:
1368                         /* already deleted by self; nothing to do */
1369                         return;
1370
1371                 case HeapTupleMayBeUpdated:
1372                         break;
1373
1374                 case HeapTupleUpdated:
1375                         if (XactIsoLevel == XACT_SERIALIZABLE)
1376                                 elog(ERROR, "Can't serialize access due to concurrent update");
1377                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1378                         {
1379                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1380                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1381
1382                                 if (!TupIsNull(epqslot))
1383                                 {
1384                                         *tupleid = ctid;
1385                                         goto ldelete;
1386                                 }
1387                         }
1388                         /* tuple already deleted; nothing to do */
1389                         return;
1390
1391                 default:
1392                         elog(ERROR, "Unknown status %u from heap_delete", result);
1393                         return;
1394         }
1395
1396         IncrDeleted();
1397         (estate->es_processed)++;
1398
1399         /*
1400          * Note: Normally one would think that we have to delete index tuples
1401          * associated with the heap tuple now..
1402          *
1403          * ... but in POSTGRES, we have no need to do this because the vacuum
1404          * daemon automatically opens an index scan and deletes index tuples
1405          * when it finds deleted heap tuples. -cim 9/27/89
1406          */
1407
1408         /* AFTER ROW DELETE Triggers */
1409         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1410 }
1411
1412 /* ----------------------------------------------------------------
1413  *              ExecUpdate
1414  *
1415  *              note: we can't run UPDATE queries with transactions
1416  *              off because UPDATEs are actually INSERTs and our
1417  *              scan will mistakenly loop forever, updating the tuple
1418  *              it just inserted..      This should be fixed but until it
1419  *              is, we don't want to get stuck in an infinite loop
1420  *              which corrupts your database..
1421  * ----------------------------------------------------------------
1422  */
1423 static void
1424 ExecUpdate(TupleTableSlot *slot,
1425                    ItemPointer tupleid,
1426                    EState *estate)
1427 {
1428         HeapTuple       tuple;
1429         ResultRelInfo *resultRelInfo;
1430         Relation        resultRelationDesc;
1431         ItemPointerData ctid;
1432         int                     result;
1433         int                     numIndices;
1434
1435         /*
1436          * abort the operation if not running transactions
1437          */
1438         if (IsBootstrapProcessingMode())
1439         {
1440                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1441                 return;
1442         }
1443
1444         /*
1445          * get the heap tuple out of the tuple table slot
1446          */
1447         tuple = slot->val;
1448
1449         /*
1450          * get information on the (current) result relation
1451          */
1452         resultRelInfo = estate->es_result_relation_info;
1453         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1454
1455         /* BEFORE ROW UPDATE Triggers */
1456         if (resultRelInfo->ri_TrigDesc &&
1457           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1458         {
1459                 HeapTuple       newtuple;
1460
1461                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1462                                                                                 tupleid, tuple);
1463
1464                 if (newtuple == NULL)   /* "do nothing" */
1465                         return;
1466
1467                 if (newtuple != tuple)  /* modified by Trigger(s) */
1468                 {
1469                         /*
1470                          * Insert modified tuple into tuple table slot, replacing the
1471                          * original.  We assume that it was allocated in per-tuple
1472                          * memory context, and therefore will go away by itself. The
1473                          * tuple table slot should not try to clear it.
1474                          */
1475                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1476                         tuple = newtuple;
1477                 }
1478         }
1479
1480         /*
1481          * Check the constraints of the tuple
1482          *
1483          * If we generate a new candidate tuple after EvalPlanQual testing, we
1484          * must loop back here and recheck constraints.  (We don't need to
1485          * redo triggers, however.      If there are any BEFORE triggers then
1486          * trigger.c will have done mark4update to lock the correct tuple, so
1487          * there's no need to do them again.)
1488          */
1489 lreplace:;
1490         if (resultRelationDesc->rd_att->constr)
1491                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1492
1493         /*
1494          * replace the heap tuple
1495          */
1496         result = heap_update(resultRelationDesc, tupleid, tuple,
1497                                                  &ctid,
1498                                                  estate->es_snapshot->curcid);
1499         switch (result)
1500         {
1501                 case HeapTupleSelfUpdated:
1502                         /* already deleted by self; nothing to do */
1503                         return;
1504
1505                 case HeapTupleMayBeUpdated:
1506                         break;
1507
1508                 case HeapTupleUpdated:
1509                         if (XactIsoLevel == XACT_SERIALIZABLE)
1510                                 elog(ERROR, "Can't serialize access due to concurrent update");
1511                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1512                         {
1513                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1514                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1515
1516                                 if (!TupIsNull(epqslot))
1517                                 {
1518                                         *tupleid = ctid;
1519                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1520                                         slot = ExecStoreTuple(tuple,
1521                                                                         estate->es_junkFilter->jf_resultSlot,
1522                                                                                   InvalidBuffer, true);
1523                                         goto lreplace;
1524                                 }
1525                         }
1526                         /* tuple already deleted; nothing to do */
1527                         return;
1528
1529                 default:
1530                         elog(ERROR, "Unknown status %u from heap_update", result);
1531                         return;
1532         }
1533
1534         IncrReplaced();
1535         (estate->es_processed)++;
1536
1537         /*
1538          * Note: instead of having to update the old index tuples associated
1539          * with the heap tuple, all we do is form and insert new index tuples.
1540          * This is because UPDATEs are actually DELETEs and INSERTs and index
1541          * tuple deletion is done automagically by the vacuum daemon. All we
1542          * do is insert new index tuples.  -cim 9/27/89
1543          */
1544
1545         /*
1546          * process indices
1547          *
1548          * heap_update updates a tuple in the base relation by invalidating it
1549          * and then inserting a new tuple to the relation.      As a side effect,
1550          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1551          * field.  So we now insert index tuples using the new tupleid stored
1552          * there.
1553          */
1554
1555         numIndices = resultRelInfo->ri_NumIndices;
1556         if (numIndices > 0)
1557                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1558
1559         /* AFTER ROW UPDATE Triggers */
1560         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1561 }
1562
1563 static char *
1564 ExecRelCheck(ResultRelInfo *resultRelInfo,
1565                          TupleTableSlot *slot, EState *estate)
1566 {
1567         Relation        rel = resultRelInfo->ri_RelationDesc;
1568         int                     ncheck = rel->rd_att->constr->num_check;
1569         ConstrCheck *check = rel->rd_att->constr->check;
1570         ExprContext *econtext;
1571         MemoryContext oldContext;
1572         List       *qual;
1573         int                     i;
1574
1575         /*
1576          * If first time through for this result relation, build expression
1577          * nodetrees for rel's constraint expressions.  Keep them in the
1578          * per-query memory context so they'll survive throughout the query.
1579          */
1580         if (resultRelInfo->ri_ConstraintExprs == NULL)
1581         {
1582                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1583                 resultRelInfo->ri_ConstraintExprs =
1584                         (List **) palloc(ncheck * sizeof(List *));
1585                 for (i = 0; i < ncheck; i++)
1586                 {
1587                         qual = (List *) stringToNode(check[i].ccbin);
1588                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1589                                 ExecPrepareExpr((Expr *) qual, estate);
1590                 }
1591                 MemoryContextSwitchTo(oldContext);
1592         }
1593
1594         /*
1595          * We will use the EState's per-tuple context for evaluating
1596          * constraint expressions (creating it if it's not already there).
1597          */
1598         econtext = GetPerTupleExprContext(estate);
1599
1600         /* Arrange for econtext's scan tuple to be the tuple under test */
1601         econtext->ecxt_scantuple = slot;
1602
1603         /* And evaluate the constraints */
1604         for (i = 0; i < ncheck; i++)
1605         {
1606                 qual = resultRelInfo->ri_ConstraintExprs[i];
1607
1608                 /*
1609                  * NOTE: SQL92 specifies that a NULL result from a constraint
1610                  * expression is not to be treated as a failure.  Therefore, tell
1611                  * ExecQual to return TRUE for NULL.
1612                  */
1613                 if (!ExecQual(qual, econtext, true))
1614                         return check[i].ccname;
1615         }
1616
1617         /* NULL result means no error */
1618         return (char *) NULL;
1619 }
1620
1621 void
1622 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1623                                 TupleTableSlot *slot, EState *estate)
1624 {
1625         Relation        rel = resultRelInfo->ri_RelationDesc;
1626         HeapTuple       tuple = slot->val;
1627         TupleConstr *constr = rel->rd_att->constr;
1628
1629         Assert(constr);
1630
1631         if (constr->has_not_null)
1632         {
1633                 int                     natts = rel->rd_att->natts;
1634                 int                     attrChk;
1635
1636                 for (attrChk = 1; attrChk <= natts; attrChk++)
1637                 {
1638                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1639                                 heap_attisnull(tuple, attrChk))
1640                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1641                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1642                 }
1643         }
1644
1645         if (constr->num_check > 0)
1646         {
1647                 char       *failed;
1648
1649                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1650                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1651                                  caller, failed, RelationGetRelationName(rel));
1652         }
1653 }
1654
1655 /*
1656  * Check a modified tuple to see if we want to process its updated version
1657  * under READ COMMITTED rules.
1658  *
1659  * See backend/executor/README for some info about how this works.
1660  */
1661 TupleTableSlot *
1662 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1663 {
1664         evalPlanQual *epq;
1665         EState     *epqstate;
1666         Relation        relation;
1667         HeapTupleData tuple;
1668         HeapTuple       copyTuple = NULL;
1669         bool            endNode;
1670
1671         Assert(rti != 0);
1672
1673         /*
1674          * find relation containing target tuple
1675          */
1676         if (estate->es_result_relation_info != NULL &&
1677                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1678                 relation = estate->es_result_relation_info->ri_RelationDesc;
1679         else
1680         {
1681                 List       *l;
1682
1683                 relation = NULL;
1684                 foreach(l, estate->es_rowMark)
1685                 {
1686                         if (((execRowMark *) lfirst(l))->rti == rti)
1687                         {
1688                                 relation = ((execRowMark *) lfirst(l))->relation;
1689                                 break;
1690                         }
1691                 }
1692                 if (relation == NULL)
1693                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1694         }
1695
1696         /*
1697          * fetch tid tuple
1698          *
1699          * Loop here to deal with updated or busy tuples
1700          */
1701         tuple.t_self = *tid;
1702         for (;;)
1703         {
1704                 Buffer          buffer;
1705
1706                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1707                 {
1708                         TransactionId xwait = SnapshotDirty->xmax;
1709
1710                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1711                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1712
1713                         /*
1714                          * If tuple is being updated by other transaction then we have
1715                          * to wait for its commit/abort.
1716                          */
1717                         if (TransactionIdIsValid(xwait))
1718                         {
1719                                 ReleaseBuffer(buffer);
1720                                 XactLockTableWait(xwait);
1721                                 continue;
1722                         }
1723
1724                         /*
1725                          * We got tuple - now copy it for use by recheck query.
1726                          */
1727                         copyTuple = heap_copytuple(&tuple);
1728                         ReleaseBuffer(buffer);
1729                         break;
1730                 }
1731
1732                 /*
1733                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1734                  * Note that it's possible to get invalid SnapshotDirty->tid if
1735                  * tuple updated by this transaction. Have we to check this ?
1736                  */
1737                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1738                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1739                 {
1740                         /* updated, so look at the updated copy */
1741                         tuple.t_self = SnapshotDirty->tid;
1742                         continue;
1743                 }
1744
1745                 /*
1746                  * Deleted or updated by this transaction; forget it.
1747                  */
1748                 return NULL;
1749         }
1750
1751         /*
1752          * For UPDATE/DELETE we have to return tid of actual row we're
1753          * executing PQ for.
1754          */
1755         *tid = tuple.t_self;
1756
1757         /*
1758          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1759          */
1760         epq = estate->es_evalPlanQual;
1761         endNode = true;
1762
1763         if (epq != NULL && epq->rti == 0)
1764         {
1765                 /* Top PQ stack entry is idle, so re-use it */
1766                 Assert(!(estate->es_useEvalPlan) && epq->next == NULL);
1767                 epq->rti = rti;
1768                 endNode = false;
1769         }
1770
1771         /*
1772          * If this is request for another RTE - Ra, - then we have to check
1773          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1774          * updated again and we have to re-start old execution for Ra and
1775          * forget all what we done after Ra was suspended. Cool? -:))
1776          */
1777         if (epq != NULL && epq->rti != rti &&
1778                 epq->estate->es_evTuple[rti - 1] != NULL)
1779         {
1780                 do
1781                 {
1782                         evalPlanQual *oldepq;
1783
1784                         /* stop execution */
1785                         EvalPlanQualStop(epq);
1786                         /* pop previous PlanQual from the stack */
1787                         oldepq = epq->next;
1788                         Assert(oldepq && oldepq->rti != 0);
1789                         /* push current PQ to freePQ stack */
1790                         oldepq->free = epq;
1791                         epq = oldepq;
1792                         estate->es_evalPlanQual = epq;
1793                 } while (epq->rti != rti);
1794         }
1795
1796         /*
1797          * If we are requested for another RTE then we have to suspend
1798          * execution of current PlanQual and start execution for new one.
1799          */
1800         if (epq == NULL || epq->rti != rti)
1801         {
1802                 /* try to reuse plan used previously */
1803                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1804
1805                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1806                 {
1807                         newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual));
1808                         newepq->free = NULL;
1809                         newepq->estate = NULL;
1810                         newepq->planstate = NULL;
1811                 }
1812                 else
1813                 {
1814                         /* recycle previously used PlanQual */
1815                         Assert(newepq->estate == NULL);
1816                         epq->free = NULL;
1817                 }
1818                 /* push current PQ to the stack */
1819                 newepq->next = epq;
1820                 epq = newepq;
1821                 estate->es_evalPlanQual = epq;
1822                 epq->rti = rti;
1823                 endNode = false;
1824         }
1825
1826         Assert(epq->rti == rti);
1827
1828         /*
1829          * Ok - we're requested for the same RTE.  Unfortunately we still have
1830          * to end and restart execution of the plan, because ExecReScan
1831          * wouldn't ensure that upper plan nodes would reset themselves.  We
1832          * could make that work if insertion of the target tuple were
1833          * integrated with the Param mechanism somehow, so that the upper plan
1834          * nodes know that their children's outputs have changed.
1835          *
1836          * Note that the stack of free evalPlanQual nodes is quite useless at
1837          * the moment, since it only saves us from pallocing/releasing the
1838          * evalPlanQual nodes themselves.  But it will be useful once we
1839          * implement ReScan instead of end/restart for re-using PlanQual nodes.
1840          */
1841         if (endNode)
1842         {
1843                 /* stop execution */
1844                 EvalPlanQualStop(epq);
1845         }
1846
1847         /*
1848          * Initialize new recheck query.
1849          *
1850          * Note: if we were re-using PlanQual plans via ExecReScan, we'd need
1851          * to instead copy down changeable state from the top plan (including
1852          * es_result_relation_info, es_junkFilter) and reset locally changeable
1853          * state in the epq (including es_param_exec_vals, es_evTupleNull).
1854          */
1855         EvalPlanQualStart(epq, estate, epq->next);
1856
1857         /*
1858          * free old RTE' tuple, if any, and store target tuple where
1859          * relation's scan node will see it
1860          */
1861         epqstate = epq->estate;
1862         if (epqstate->es_evTuple[rti - 1] != NULL)
1863                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1864         epqstate->es_evTuple[rti - 1] = copyTuple;
1865
1866         return EvalPlanQualNext(estate);
1867 }
1868
1869 static TupleTableSlot *
1870 EvalPlanQualNext(EState *estate)
1871 {
1872         evalPlanQual *epq = estate->es_evalPlanQual;
1873         MemoryContext oldcontext;
1874         TupleTableSlot *slot;
1875
1876         Assert(epq->rti != 0);
1877
1878 lpqnext:;
1879         oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt);
1880         slot = ExecProcNode(epq->planstate);
1881         MemoryContextSwitchTo(oldcontext);
1882
1883         /*
1884          * No more tuples for this PQ. Continue previous one.
1885          */
1886         if (TupIsNull(slot))
1887         {
1888                 evalPlanQual *oldepq;
1889
1890                 /* stop execution */
1891                 EvalPlanQualStop(epq);
1892                 /* pop old PQ from the stack */
1893                 oldepq = epq->next;
1894                 if (oldepq == NULL)
1895                 {
1896                         /* this is the first (oldest) PQ - mark as free */
1897                         epq->rti = 0;
1898                         estate->es_useEvalPlan = false;
1899                         /* and continue Query execution */
1900                         return (NULL);
1901                 }
1902                 Assert(oldepq->rti != 0);
1903                 /* push current PQ to freePQ stack */
1904                 oldepq->free = epq;
1905                 epq = oldepq;
1906                 estate->es_evalPlanQual = epq;
1907                 goto lpqnext;
1908         }
1909
1910         return (slot);
1911 }
1912
1913 static void
1914 EndEvalPlanQual(EState *estate)
1915 {
1916         evalPlanQual *epq = estate->es_evalPlanQual;
1917
1918         if (epq->rti == 0)                      /* plans already shutdowned */
1919         {
1920                 Assert(epq->next == NULL);
1921                 return;
1922         }
1923
1924         for (;;)
1925         {
1926                 evalPlanQual *oldepq;
1927
1928                 /* stop execution */
1929                 EvalPlanQualStop(epq);
1930                 /* pop old PQ from the stack */
1931                 oldepq = epq->next;
1932                 if (oldepq == NULL)
1933                 {
1934                         /* this is the first (oldest) PQ - mark as free */
1935                         epq->rti = 0;
1936                         estate->es_useEvalPlan = false;
1937                         break;
1938                 }
1939                 Assert(oldepq->rti != 0);
1940                 /* push current PQ to freePQ stack */
1941                 oldepq->free = epq;
1942                 epq = oldepq;
1943                 estate->es_evalPlanQual = epq;
1944         }
1945 }
1946
1947 /*
1948  * Start execution of one level of PlanQual.
1949  *
1950  * This is a cut-down version of ExecutorStart(): we copy some state from
1951  * the top-level estate rather than initializing it fresh.
1952  */
1953 static void
1954 EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
1955 {
1956         EState     *epqstate;
1957         int                     rtsize;
1958         MemoryContext oldcontext;
1959
1960         rtsize = length(estate->es_range_table);
1961
1962         epq->estate = epqstate = CreateExecutorState();
1963
1964         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1965
1966         /*
1967          * The epqstates share the top query's copy of unchanging state such
1968          * as the snapshot, rangetable, result-rel info, and external Param info.
1969          * They need their own copies of local state, including a tuple table,
1970          * es_param_exec_vals, etc.
1971          */
1972         epqstate->es_direction = ForwardScanDirection;
1973         epqstate->es_snapshot = estate->es_snapshot;
1974         epqstate->es_range_table = estate->es_range_table;
1975         epqstate->es_result_relations = estate->es_result_relations;
1976         epqstate->es_num_result_relations = estate->es_num_result_relations;
1977         epqstate->es_result_relation_info = estate->es_result_relation_info;
1978         epqstate->es_junkFilter = estate->es_junkFilter;
1979         epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor;
1980         epqstate->es_param_list_info = estate->es_param_list_info;
1981         if (estate->es_topPlan->nParamExec > 0)
1982                 epqstate->es_param_exec_vals = (ParamExecData *)
1983                         palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
1984         epqstate->es_rowMark = estate->es_rowMark;
1985         epqstate->es_instrument = estate->es_instrument;
1986         epqstate->es_force_oids = estate->es_force_oids;
1987         epqstate->es_topPlan = estate->es_topPlan;
1988         /*
1989          * Each epqstate must have its own es_evTupleNull state, but
1990          * all the stack entries share es_evTuple state.  This allows
1991          * sub-rechecks to inherit the value being examined by an
1992          * outer recheck.
1993          */
1994         epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool));
1995         if (priorepq == NULL)
1996                 /* first PQ stack entry */
1997                 epqstate->es_evTuple = (HeapTuple *)
1998                         palloc0(rtsize * sizeof(HeapTuple));
1999         else
2000                 /* later stack entries share the same storage */
2001                 epqstate->es_evTuple = priorepq->estate->es_evTuple;
2002
2003         epqstate->es_tupleTable =
2004                 ExecCreateTupleTable(estate->es_tupleTable->size);
2005
2006         epq->planstate = ExecInitNode(estate->es_topPlan, epqstate);
2007
2008         MemoryContextSwitchTo(oldcontext);
2009 }
2010
2011 /*
2012  * End execution of one level of PlanQual.
2013  *
2014  * This is a cut-down version of ExecutorEnd(); basically we want to do most
2015  * of the normal cleanup, but *not* close result relations (which we are
2016  * just sharing from the outer query).
2017  */
2018 static void
2019 EvalPlanQualStop(evalPlanQual *epq)
2020 {
2021         EState     *epqstate = epq->estate;
2022         MemoryContext oldcontext;
2023
2024         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
2025
2026         ExecEndNode(epq->planstate);
2027
2028         ExecDropTupleTable(epqstate->es_tupleTable, true);
2029         epqstate->es_tupleTable = NULL;
2030
2031         if (epqstate->es_evTuple[epq->rti - 1] != NULL)
2032         {
2033                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
2034                 epqstate->es_evTuple[epq->rti - 1] = NULL;
2035         }
2036
2037         MemoryContextSwitchTo(oldcontext);
2038
2039         FreeExecutorState(epqstate);
2040
2041         epq->estate = NULL;
2042         epq->planstate = NULL;
2043 }