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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 and the execution state is required
  16  *       as arguments
  17  *
  18  *      ExecutorStart() must be called at the beginning of any execution of any
  19  *      query plan and ExecutorEnd() should always be called at the end of
  20  *      execution of a plan.
  21  *
  22  *      ExecutorRun accepts direction and count arguments that specify whether
  23  *      the plan is to be executed forwards, backwards, and for how many tuples.
  24  *
  25  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  26  * Portions Copyright (c) 1994, Regents of the University of California
  27  *
  28  *
  29  * IDENTIFICATION
  30  *        $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.177 2002/09/02 01:05:05 tgl Exp $
  31  *
  32  *-------------------------------------------------------------------------
  33  */
  34 #include "postgres.h"
  35
  36 #include "access/heapam.h"
  37 #include "catalog/heap.h"
  38 #include "catalog/namespace.h"
  39 #include "commands/tablecmds.h"
  40 #include "commands/trigger.h"
  41 #include "executor/execdebug.h"
  42 #include "executor/execdefs.h"
  43 #include "miscadmin.h"
  44 #include "optimizer/var.h"
  45 #include "parser/parsetree.h"
  46 #include "utils/acl.h"
  47 #include "utils/lsyscache.h"
  48
  49
  50 /* decls for local routines only used within this module */
  51 static TupleDesc InitPlan(CmdType operation,
  52                  Query *parseTree,
  53                  Plan *plan,
  54                  EState *estate);
  55 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  56                                   Index resultRelationIndex,
  57                                   List *rangeTable,
  58                                   CmdType operation);
  59 static void EndPlan(Plan *plan, EState *estate);
  60 static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan,
  61                         CmdType operation,
  62                         long numberTuples,
  63                         ScanDirection direction,
  64                         DestReceiver *destfunc);
  65 static void ExecSelect(TupleTableSlot *slot,
  66                          DestReceiver *destfunc,
  67                          EState *estate);
  68 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  69                    EState *estate);
  70 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  71                    EState *estate);
  72 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  73                         EState *estate);
  74 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  75 static void EndEvalPlanQual(EState *estate);
  76 static void ExecCheckQueryPerms(CmdType operation, Query *parseTree,
  77                                         Plan *plan);
  78 static void ExecCheckPlanPerms(Plan *plan, List *rangeTable,
  79                                    CmdType operation);
  80 static void ExecCheckRTPerms(List *rangeTable, CmdType operation);
  81 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  82
  83 /* end of local decls */
  84
  85
  86 /* ----------------------------------------------------------------
  87  *              ExecutorStart
  88  *
  89  *              This routine must be called at the beginning of any execution of any
  90  *              query plan
  91  *
  92  *              returns a TupleDesc which describes the attributes of the tuples to
  93  *              be returned by the query.  (Same value is saved in queryDesc)
  94  *
  95  * NB: the CurrentMemoryContext when this is called must be the context
  96  * to be used as the per-query context for the query plan.      ExecutorRun()
  97  * and ExecutorEnd() must be called in this same memory context.
  98  * ----------------------------------------------------------------
  99  */
 100 TupleDesc
 101 ExecutorStart(QueryDesc *queryDesc, EState *estate)
 102 {
 103         TupleDesc       result;
 104
 105         /* sanity checks */
 106         Assert(queryDesc != NULL);
 107
 108         if (queryDesc->plantree->nParamExec > 0)
 109         {
 110                 estate->es_param_exec_vals = (ParamExecData *)
 111                         palloc(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 112                 MemSet(estate->es_param_exec_vals, 0,
 113                            queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 114         }
 115
 116         /*
 117          * Make our own private copy of the current query snapshot data.
 118          *
 119          * This "freezes" our idea of which tuples are good and which are not
 120          * for the life of this query, even if it outlives the current command
 121          * and current snapshot.
 122          */
 123         estate->es_snapshot = CopyQuerySnapshot();
 124
 125         /*
 126          * Initialize the plan
 127          */
 128         result = InitPlan(queryDesc->operation,
 129                                           queryDesc->parsetree,
 130                                           queryDesc->plantree,
 131                                           estate);
 132
 133         queryDesc->tupDesc = result;
 134
 135         return result;
 136 }
 137
 138 /* ----------------------------------------------------------------
 139  *              ExecutorRun
 140  *
 141  *              This is the main routine of the executor module. It accepts
 142  *              the query descriptor from the traffic cop and executes the
 143  *              query plan.
 144  *
 145  *              ExecutorStart must have been called already.
 146  *
 147  *              If direction is NoMovementScanDirection then nothing is done
 148  *              except to start up/shut down the destination.  Otherwise,
 149  *              we retrieve up to 'count' tuples in the specified direction.
 150  *
 151  *              Note: count = 0 is interpreted as no portal limit, e.g. run to
 152  *              completion.
 153  *
 154  * ----------------------------------------------------------------
 155  */
 156 TupleTableSlot *
 157 ExecutorRun(QueryDesc *queryDesc, EState *estate,
 158                         ScanDirection direction, long count)
 159 {
 160         CmdType         operation;
 161         Plan       *plan;
 162         CommandDest dest;
 163         DestReceiver *destfunc;
 164         TupleTableSlot *result;
 165
 166         /*
 167          * sanity checks
 168          */
 169         Assert(queryDesc != NULL);
 170
 171         /*
 172          * extract information from the query descriptor and the query
 173          * feature.
 174          */
 175         operation = queryDesc->operation;
 176         plan = queryDesc->plantree;
 177         dest = queryDesc->dest;
 178
 179         /*
 180          * startup tuple receiver
 181          */
 182         estate->es_processed = 0;
 183         estate->es_lastoid = InvalidOid;
 184
 185         destfunc = DestToFunction(dest);
 186         (*destfunc->setup) (destfunc, (int) operation,
 187                                                 queryDesc->portalName, queryDesc->tupDesc);
 188
 189         /*
 190          * run plan
 191          */
 192         if (direction == NoMovementScanDirection)
 193                 result = NULL;
 194         else
 195                 result = ExecutePlan(estate,
 196                                                          plan,
 197                                                          operation,
 198                                                          count,
 199                                                          direction,
 200                                                          destfunc);
 201
 202         /*
 203          * shutdown receiver
 204          */
 205         (*destfunc->cleanup) (destfunc);
 206
 207         return result;
 208 }
 209
 210 /* ----------------------------------------------------------------
 211  *              ExecutorEnd
 212  *
 213  *              This routine must be called at the end of execution of any
 214  *              query plan
 215  * ----------------------------------------------------------------
 216  */
 217 void
 218 ExecutorEnd(QueryDesc *queryDesc, EState *estate)
 219 {
 220         /* sanity checks */
 221         Assert(queryDesc != NULL);
 222
 223         EndPlan(queryDesc->plantree, estate);
 224
 225         if (estate->es_snapshot != NULL)
 226         {
 227                 if (estate->es_snapshot->xcnt > 0)
 228                         pfree(estate->es_snapshot->xip);
 229                 pfree(estate->es_snapshot);
 230                 estate->es_snapshot = NULL;
 231         }
 232
 233         if (estate->es_param_exec_vals != NULL)
 234         {
 235                 pfree(estate->es_param_exec_vals);
 236                 estate->es_param_exec_vals = NULL;
 237         }
 238 }
 239
 240
 241 /*
 242  * ExecCheckQueryPerms
 243  *              Check access permissions for all relations referenced in a query.
 244  */
 245 static void
 246 ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan)
 247 {
 248         /*
 249          * Check RTEs in the query's primary rangetable.
 250          */
 251         ExecCheckRTPerms(parseTree->rtable, operation);
 252
 253         /*
 254          * Search for subplans and APPEND nodes to check their rangetables.
 255          */
 256         ExecCheckPlanPerms(plan, parseTree->rtable, operation);
 257 }
 258
 259 /*
 260  * ExecCheckPlanPerms
 261  *              Recursively scan the plan tree to check access permissions in
 262  *              subplans.
 263  */
 264 static void
 265 ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation)
 266 {
 267         List       *subp;
 268
 269         if (plan == NULL)
 270                 return;
 271
 272         /* Check subplans, which we assume are plain SELECT queries */
 273
 274         foreach(subp, plan->initPlan)
 275         {
 276                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 277
 278                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 279                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 280         }
 281         foreach(subp, plan->subPlan)
 282         {
 283                 SubPlan    *subplan = (SubPlan *) lfirst(subp);
 284
 285                 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
 286                 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
 287         }
 288
 289         /* Check lower plan nodes */
 290
 291         ExecCheckPlanPerms(plan->lefttree, rangeTable, operation);
 292         ExecCheckPlanPerms(plan->righttree, rangeTable, operation);
 293
 294         /* Do node-type-specific checks */
 295
 296         switch (nodeTag(plan))
 297         {
 298                 case T_SubqueryScan:
 299                         {
 300                                 SubqueryScan *scan = (SubqueryScan *) plan;
 301                                 RangeTblEntry *rte;
 302
 303                                 /* Recursively check the subquery */
 304                                 rte = rt_fetch(scan->scan.scanrelid, rangeTable);
 305                                 Assert(rte->rtekind == RTE_SUBQUERY);
 306                                 ExecCheckQueryPerms(operation, rte->subquery, scan->subplan);
 307                                 break;
 308                         }
 309                 case T_Append:
 310                         {
 311                                 Append     *app = (Append *) plan;
 312                                 List       *appendplans;
 313
 314                                 foreach(appendplans, app->appendplans)
 315                                 {
 316                                         ExecCheckPlanPerms((Plan *) lfirst(appendplans),
 317                                                                            rangeTable,
 318                                                                            operation);
 319                                 }
 320                                 break;
 321                         }
 322
 323                 default:
 324                         break;
 325         }
 326 }
 327
 328 /*
 329  * ExecCheckRTPerms
 330  *              Check access permissions for all relations listed in a range table.
 331  */
 332 static void
 333 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 334 {
 335         List       *lp;
 336
 337         foreach(lp, rangeTable)
 338         {
 339                 RangeTblEntry *rte = lfirst(lp);
 340
 341                 ExecCheckRTEPerms(rte, operation);
 342         }
 343 }
 344
 345 /*
 346  * ExecCheckRTEPerms
 347  *              Check access permissions for a single RTE.
 348  */
 349 static void
 350 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 351 {
 352         Oid                     relOid;
 353         Oid                     userid;
 354         AclResult       aclcheck_result;
 355
 356         /*
 357          * Only plain-relation RTEs need to be checked here.  Subquery RTEs
 358          * will be checked when ExecCheckPlanPerms finds the SubqueryScan node,
 359          * and function RTEs are checked by init_fcache when the function is
 360          * prepared for execution.  Join and special RTEs need no checks.
 361          */
 362         if (rte->rtekind != RTE_RELATION)
 363                 return;
 364
 365         relOid = rte->relid;
 366
 367         /*
 368          * userid to check as: current user unless we have a setuid
 369          * indication.
 370          *
 371          * Note: GetUserId() is presently fast enough that there's no harm in
 372          * calling it separately for each RTE.  If that stops being true, we
 373          * could call it once in ExecCheckQueryPerms and pass the userid down
 374          * from there.  But for now, no need for the extra clutter.
 375          */
 376         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 377
 378 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 379
 380         if (rte->checkForRead)
 381         {
 382                 aclcheck_result = CHECK(ACL_SELECT);
 383                 if (aclcheck_result != ACLCHECK_OK)
 384                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 385         }
 386
 387         if (rte->checkForWrite)
 388         {
 389                 /*
 390                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 391                  * Right now we don't distinguish that from true update as far as
 392                  * permissions checks are concerned.
 393                  */
 394                 switch (operation)
 395                 {
 396                         case CMD_INSERT:
 397                                 aclcheck_result = CHECK(ACL_INSERT);
 398                                 break;
 399                         case CMD_SELECT:
 400                         case CMD_UPDATE:
 401                                 aclcheck_result = CHECK(ACL_UPDATE);
 402                                 break;
 403                         case CMD_DELETE:
 404                                 aclcheck_result = CHECK(ACL_DELETE);
 405                                 break;
 406                         default:
 407                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 408                                          operation);
 409                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 410                                 break;
 411                 }
 412                 if (aclcheck_result != ACLCHECK_OK)
 413                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 414         }
 415 }
 416
 417
 418 /* ===============================================================
 419  * ===============================================================
 420                                                  static routines follow
 421  * ===============================================================
 422  * ===============================================================
 423  */
 424
 425 typedef struct execRowMark
 426 {
 427         Relation        relation;
 428         Index           rti;
 429         char            resname[32];
 430 } execRowMark;
 431
 432 typedef struct evalPlanQual
 433 {
 434         Plan       *plan;
 435         Index           rti;
 436         EState          estate;
 437         struct evalPlanQual *free;
 438 } evalPlanQual;
 439
 440 /* ----------------------------------------------------------------
 441  *              InitPlan
 442  *
 443  *              Initializes the query plan: open files, allocate storage
 444  *              and start up the rule manager
 445  * ----------------------------------------------------------------
 446  */
 447 static TupleDesc
 448 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 449 {
 450         List       *rangeTable;
 451         Relation        intoRelationDesc;
 452         TupleDesc       tupType;
 453
 454         /*
 455          * Do permissions checks.
 456          */
 457         ExecCheckQueryPerms(operation, parseTree, plan);
 458
 459         /*
 460          * get information from query descriptor
 461          */
 462         rangeTable = parseTree->rtable;
 463
 464         /*
 465          * initialize the node's execution state
 466          */
 467         estate->es_range_table = rangeTable;
 468
 469         /*
 470          * if there is a result relation, initialize result relation stuff
 471          */
 472         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 473         {
 474                 List       *resultRelations = parseTree->resultRelations;
 475                 int                     numResultRelations;
 476                 ResultRelInfo *resultRelInfos;
 477
 478                 if (resultRelations != NIL)
 479                 {
 480                         /*
 481                          * Multiple result relations (due to inheritance)
 482                          * parseTree->resultRelations identifies them all
 483                          */
 484                         ResultRelInfo *resultRelInfo;
 485
 486                         numResultRelations = length(resultRelations);
 487                         resultRelInfos = (ResultRelInfo *)
 488                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 489                         resultRelInfo = resultRelInfos;
 490                         while (resultRelations != NIL)
 491                         {
 492                                 initResultRelInfo(resultRelInfo,
 493                                                                   lfirsti(resultRelations),
 494                                                                   rangeTable,
 495                                                                   operation);
 496                                 resultRelInfo++;
 497                                 resultRelations = lnext(resultRelations);
 498                         }
 499                 }
 500                 else
 501                 {
 502                         /*
 503                          * Single result relation identified by
 504                          * parseTree->resultRelation
 505                          */
 506                         numResultRelations = 1;
 507                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 508                         initResultRelInfo(resultRelInfos,
 509                                                           parseTree->resultRelation,
 510                                                           rangeTable,
 511                                                           operation);
 512                 }
 513
 514                 estate->es_result_relations = resultRelInfos;
 515                 estate->es_num_result_relations = numResultRelations;
 516                 /* Initialize to first or only result rel */
 517                 estate->es_result_relation_info = resultRelInfos;
 518         }
 519         else
 520         {
 521                 /*
 522                  * if no result relation, then set state appropriately
 523                  */
 524                 estate->es_result_relations = NULL;
 525                 estate->es_num_result_relations = 0;
 526                 estate->es_result_relation_info = NULL;
 527         }
 528
 529         /*
 530          * Have to lock relations selected for update
 531          */
 532         estate->es_rowMark = NIL;
 533         if (parseTree->rowMarks != NIL)
 534         {
 535                 List       *l;
 536
 537                 foreach(l, parseTree->rowMarks)
 538                 {
 539                         Index           rti = lfirsti(l);
 540                         Oid                     relid = getrelid(rti, rangeTable);
 541                         Relation        relation;
 542                         execRowMark *erm;
 543
 544                         relation = heap_open(relid, RowShareLock);
 545                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 546                         erm->relation = relation;
 547                         erm->rti = rti;
 548                         snprintf(erm->resname, 32, "ctid%u", rti);
 549                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 550                 }
 551         }
 552
 553         /*
 554          * initialize the executor "tuple" table.  We need slots for all the
 555          * plan nodes, plus possibly output slots for the junkfilter(s). At
 556          * this point we aren't sure if we need junkfilters, so just add slots
 557          * for them unconditionally.
 558          */
 559         {
 560                 int                     nSlots = ExecCountSlotsNode(plan);
 561
 562                 if (parseTree->resultRelations != NIL)
 563                         nSlots += length(parseTree->resultRelations);
 564                 else
 565                         nSlots += 1;
 566                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 567         }
 568
 569         /* mark EvalPlanQual not active */
 570         estate->es_origPlan = plan;
 571         estate->es_evalPlanQual = NULL;
 572         estate->es_evTuple = NULL;
 573         estate->es_evTupleNull = NULL;
 574         estate->es_useEvalPlan = false;
 575
 576         /*
 577          * initialize the private state information for all the nodes in the
 578          * query tree.  This opens files, allocates storage and leaves us
 579          * ready to start processing tuples.
 580          */
 581         ExecInitNode(plan, estate, NULL);
 582
 583         /*
 584          * Get the tuple descriptor describing the type of tuples to return.
 585          * (this is especially important if we are creating a relation with
 586          * "SELECT INTO")
 587          */
 588         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 589
 590         /*
 591          * Initialize the junk filter if needed. SELECT and INSERT queries
 592          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 593          * DELETE always need one, since there's always a junk 'ctid'
 594          * attribute present --- no need to look first.
 595          */
 596         {
 597                 bool            junk_filter_needed = false;
 598                 List       *tlist;
 599
 600                 switch (operation)
 601                 {
 602                         case CMD_SELECT:
 603                         case CMD_INSERT:
 604                                 foreach(tlist, plan->targetlist)
 605                                 {
 606                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 607
 608                                         if (tle->resdom->resjunk)
 609                                         {
 610                                                 junk_filter_needed = true;
 611                                                 break;
 612                                         }
 613                                 }
 614                                 break;
 615                         case CMD_UPDATE:
 616                         case CMD_DELETE:
 617                                 junk_filter_needed = true;
 618                                 break;
 619                         default:
 620                                 break;
 621                 }
 622
 623                 if (junk_filter_needed)
 624                 {
 625                         /*
 626                          * If there are multiple result relations, each one needs its
 627                          * own junk filter.  Note this is only possible for
 628                          * UPDATE/DELETE, so we can't be fooled by some needing a
 629                          * filter and some not.
 630                          */
 631                         if (parseTree->resultRelations != NIL)
 632                         {
 633                                 List       *subplans;
 634                                 ResultRelInfo *resultRelInfo;
 635
 636                                 /* Top plan had better be an Append here. */
 637                                 Assert(IsA(plan, Append));
 638                                 Assert(((Append *) plan)->isTarget);
 639                                 subplans = ((Append *) plan)->appendplans;
 640                                 Assert(length(subplans) == estate->es_num_result_relations);
 641                                 resultRelInfo = estate->es_result_relations;
 642                                 while (subplans != NIL)
 643                                 {
 644                                         Plan       *subplan = (Plan *) lfirst(subplans);
 645                                         JunkFilter *j;
 646
 647                                         j = ExecInitJunkFilter(subplan->targetlist,
 648                                                                                    ExecGetTupType(subplan),
 649                                                           ExecAllocTableSlot(estate->es_tupleTable));
 650                                         resultRelInfo->ri_junkFilter = j;
 651                                         resultRelInfo++;
 652                                         subplans = lnext(subplans);
 653                                 }
 654
 655                                 /*
 656                                  * Set active junkfilter too; at this point ExecInitAppend
 657                                  * has already selected an active result relation...
 658                                  */
 659                                 estate->es_junkFilter =
 660                                         estate->es_result_relation_info->ri_junkFilter;
 661                         }
 662                         else
 663                         {
 664                                 /* Normal case with just one JunkFilter */
 665                                 JunkFilter *j;
 666
 667                                 j = ExecInitJunkFilter(plan->targetlist,
 668                                                                            tupType,
 669                                                           ExecAllocTableSlot(estate->es_tupleTable));
 670                                 estate->es_junkFilter = j;
 671                                 if (estate->es_result_relation_info)
 672                                         estate->es_result_relation_info->ri_junkFilter = j;
 673
 674                                 /* For SELECT, want to return the cleaned tuple type */
 675                                 if (operation == CMD_SELECT)
 676                                         tupType = j->jf_cleanTupType;
 677                         }
 678                 }
 679                 else
 680                         estate->es_junkFilter = NULL;
 681         }
 682
 683         /*
 684          * initialize the "into" relation
 685          */
 686         intoRelationDesc = (Relation) NULL;
 687
 688         if (operation == CMD_SELECT)
 689         {
 690                 if (!parseTree->isPortal)
 691                 {
 692                         /*
 693                          * a select into table --- need to create the "into" table
 694                          */
 695                         if (parseTree->into != NULL)
 696                         {
 697                                 char       *intoName;
 698                                 Oid                     namespaceId;
 699                                 AclResult       aclresult;
 700                                 Oid                     intoRelationId;
 701                                 TupleDesc       tupdesc;
 702
 703                                 /*
 704                                  * find namespace to create in, check permissions
 705                                  */
 706                                 intoName = parseTree->into->relname;
 707                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 708
 709                                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 710                                                                                                   ACL_CREATE);
 711                                 if (aclresult != ACLCHECK_OK)
 712                                         aclcheck_error(aclresult,
 713                                                                    get_namespace_name(namespaceId));
 714
 715                                 /*
 716                                  * have to copy tupType to get rid of constraints
 717                                  */
 718                                 tupdesc = CreateTupleDescCopy(tupType);
 719
 720                                 /*
 721                                  * Formerly we forced the output table to have OIDs, but
 722                                  * as of 7.3 it will not have OIDs, because it's too late
 723                                  * here to change the tupdescs of the already-initialized
 724                                  * plan tree.  (Perhaps we could recurse and change them
 725                                  * all, but it's not really worth the trouble IMHO...)
 726                                  */
 727
 728                                 intoRelationId =
 729                                         heap_create_with_catalog(intoName,
 730                                                                                          namespaceId,
 731                                                                                          tupdesc,
 732                                                                                          RELKIND_RELATION,
 733                                                                                          false,
 734                                                                                          allowSystemTableMods);
 735
 736                                 FreeTupleDesc(tupdesc);
 737
 738                                 /*
 739                                  * Advance command counter so that the newly-created
 740                                  * relation's catalog tuples will be visible to heap_open.
 741                                  */
 742                                 CommandCounterIncrement();
 743
 744                                 /*
 745                                  * If necessary, create a TOAST table for the into
 746                                  * relation. Note that AlterTableCreateToastTable ends
 747                                  * with CommandCounterIncrement(), so that the TOAST table
 748                                  * will be visible for insertion.
 749                                  */
 750                                 AlterTableCreateToastTable(intoRelationId, true);
 751
 752                                 intoRelationDesc = heap_open(intoRelationId,
 753                                                                                          AccessExclusiveLock);
 754                         }
 755                 }
 756         }
 757
 758         estate->es_into_relation_descriptor = intoRelationDesc;
 759
 760         return tupType;
 761 }
 762
 763 /*
 764  * Initialize ResultRelInfo data for one result relation
 765  */
 766 static void
 767 initResultRelInfo(ResultRelInfo *resultRelInfo,
 768                                   Index resultRelationIndex,
 769                                   List *rangeTable,
 770                                   CmdType operation)
 771 {
 772         Oid                     resultRelationOid;
 773         Relation        resultRelationDesc;
 774
 775         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 776         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 777
 778         switch (resultRelationDesc->rd_rel->relkind)
 779         {
 780                 case RELKIND_SEQUENCE:
 781                         elog(ERROR, "You can't change sequence relation %s",
 782                                  RelationGetRelationName(resultRelationDesc));
 783                         break;
 784                 case RELKIND_TOASTVALUE:
 785                         elog(ERROR, "You can't change toast relation %s",
 786                                  RelationGetRelationName(resultRelationDesc));
 787                         break;
 788                 case RELKIND_VIEW:
 789                         elog(ERROR, "You can't change view relation %s",
 790                                  RelationGetRelationName(resultRelationDesc));
 791                         break;
 792         }
 793
 794         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 795         resultRelInfo->type = T_ResultRelInfo;
 796         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 797         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 798         resultRelInfo->ri_NumIndices = 0;
 799         resultRelInfo->ri_IndexRelationDescs = NULL;
 800         resultRelInfo->ri_IndexRelationInfo = NULL;
 801         resultRelInfo->ri_TrigDesc = resultRelationDesc->trigdesc;
 802         resultRelInfo->ri_TrigFunctions = NULL;
 803         resultRelInfo->ri_ConstraintExprs = NULL;
 804         resultRelInfo->ri_junkFilter = NULL;
 805
 806         /*
 807          * If there are indices on the result relation, open them and save
 808          * descriptors in the result relation info, so that we can add new
 809          * index entries for the tuples we add/update.  We need not do this
 810          * for a DELETE, however, since deletion doesn't affect indexes.
 811          */
 812         if (resultRelationDesc->rd_rel->relhasindex &&
 813                 operation != CMD_DELETE)
 814                 ExecOpenIndices(resultRelInfo);
 815 }
 816
 817 /* ----------------------------------------------------------------
 818  *              EndPlan
 819  *
 820  *              Cleans up the query plan -- closes files and free up storages
 821  * ----------------------------------------------------------------
 822  */
 823 static void
 824 EndPlan(Plan *plan, EState *estate)
 825 {
 826         ResultRelInfo *resultRelInfo;
 827         int                     i;
 828         List       *l;
 829
 830         /*
 831          * shut down any PlanQual processing we were doing
 832          */
 833         if (estate->es_evalPlanQual != NULL)
 834                 EndEvalPlanQual(estate);
 835
 836         /*
 837          * shut down the node-type-specific query processing
 838          */
 839         ExecEndNode(plan, NULL);
 840
 841         /*
 842          * destroy the executor "tuple" table.
 843          */
 844         ExecDropTupleTable(estate->es_tupleTable, true);
 845         estate->es_tupleTable = NULL;
 846
 847         /*
 848          * close the result relation(s) if any, but hold locks until xact
 849          * commit.      Also clean up junkfilters if present.
 850          */
 851         resultRelInfo = estate->es_result_relations;
 852         for (i = estate->es_num_result_relations; i > 0; i--)
 853         {
 854                 /* Close indices and then the relation itself */
 855                 ExecCloseIndices(resultRelInfo);
 856                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 857                 /* Delete the junkfilter if any */
 858                 if (resultRelInfo->ri_junkFilter != NULL)
 859                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 860                 resultRelInfo++;
 861         }
 862
 863         /*
 864          * close the "into" relation if necessary, again keeping lock
 865          */
 866         if (estate->es_into_relation_descriptor != NULL)
 867                 heap_close(estate->es_into_relation_descriptor, NoLock);
 868
 869         /*
 870          * There might be a junkfilter without a result relation.
 871          */
 872         if (estate->es_num_result_relations == 0 &&
 873                 estate->es_junkFilter != NULL)
 874         {
 875                 ExecFreeJunkFilter(estate->es_junkFilter);
 876                 estate->es_junkFilter = NULL;
 877         }
 878
 879         /*
 880          * close any relations selected FOR UPDATE, again keeping locks
 881          */
 882         foreach(l, estate->es_rowMark)
 883         {
 884                 execRowMark *erm = lfirst(l);
 885
 886                 heap_close(erm->relation, NoLock);
 887         }
 888 }
 889
 890 /* ----------------------------------------------------------------
 891  *              ExecutePlan
 892  *
 893  *              processes the query plan to retrieve 'numberTuples' tuples in the
 894  *              direction specified.
 895  *              Retrieves all tuples if numberTuples is 0
 896  *
 897  *              result is either a slot containing the last tuple in the case
 898  *              of a SELECT or NULL otherwise.
 899  *
 900  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 901  * user can see it
 902  * ----------------------------------------------------------------
 903  */
 904 static TupleTableSlot *
 905 ExecutePlan(EState *estate,
 906                         Plan *plan,
 907                         CmdType operation,
 908                         long numberTuples,
 909                         ScanDirection direction,
 910                         DestReceiver *destfunc)
 911 {
 912         JunkFilter *junkfilter;
 913         TupleTableSlot *slot;
 914         ItemPointer tupleid = NULL;
 915         ItemPointerData tuple_ctid;
 916         long            current_tuple_count;
 917         TupleTableSlot *result;
 918
 919         /*
 920          * initialize local variables
 921          */
 922         slot = NULL;
 923         current_tuple_count = 0;
 924         result = NULL;
 925
 926         /*
 927          * Set the direction.
 928          */
 929         estate->es_direction = direction;
 930
 931         /*
 932          * Loop until we've processed the proper number of tuples from the
 933          * plan.
 934          */
 935
 936         for (;;)
 937         {
 938                 /* Reset the per-output-tuple exprcontext */
 939                 ResetPerTupleExprContext(estate);
 940
 941                 /*
 942                  * Execute the plan and obtain a tuple
 943                  */
 944 lnext:  ;
 945                 if (estate->es_useEvalPlan)
 946                 {
 947                         slot = EvalPlanQualNext(estate);
 948                         if (TupIsNull(slot))
 949                                 slot = ExecProcNode(plan, NULL);
 950                 }
 951                 else
 952                         slot = ExecProcNode(plan, NULL);
 953
 954                 /*
 955                  * if the tuple is null, then we assume there is nothing more to
 956                  * process so we just return null...
 957                  */
 958                 if (TupIsNull(slot))
 959                 {
 960                         result = NULL;
 961                         break;
 962                 }
 963
 964                 /*
 965                  * if we have a junk filter, then project a new tuple with the
 966                  * junk removed.
 967                  *
 968                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 969                  * (Formerly, we stored it back over the "dirty" tuple, which is
 970                  * WRONG because that tuple slot has the wrong descriptor.)
 971                  *
 972                  * Also, extract all the junk information we need.
 973                  */
 974                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 975                 {
 976                         Datum           datum;
 977                         HeapTuple       newTuple;
 978                         bool            isNull;
 979
 980                         /*
 981                          * extract the 'ctid' junk attribute.
 982                          */
 983                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 984                         {
 985                                 if (!ExecGetJunkAttribute(junkfilter,
 986                                                                                   slot,
 987                                                                                   "ctid",
 988                                                                                   &datum,
 989                                                                                   &isNull))
 990                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 991
 992                                 /* shouldn't ever get a null result... */
 993                                 if (isNull)
 994                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 995
 996                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 997                                 tuple_ctid = *tupleid;  /* make sure we don't free the
 998                                                                                  * ctid!! */
 999                                 tupleid = &tuple_ctid;
1000                         }
1001                         else if (estate->es_rowMark != NIL)
1002                         {
1003                                 List       *l;
1004
1005                 lmark:  ;
1006                                 foreach(l, estate->es_rowMark)
1007                                 {
1008                                         execRowMark *erm = lfirst(l);
1009                                         Buffer          buffer;
1010                                         HeapTupleData tuple;
1011                                         TupleTableSlot *newSlot;
1012                                         int                     test;
1013
1014                                         if (!ExecGetJunkAttribute(junkfilter,
1015                                                                                           slot,
1016                                                                                           erm->resname,
1017                                                                                           &datum,
1018                                                                                           &isNull))
1019                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1020                                                          erm->resname);
1021
1022                                         /* shouldn't ever get a null result... */
1023                                         if (isNull)
1024                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1025                                                          erm->resname);
1026
1027                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1028                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1029                                                                                         estate->es_snapshot->curcid);
1030                                         ReleaseBuffer(buffer);
1031                                         switch (test)
1032                                         {
1033                                                 case HeapTupleSelfUpdated:
1034                                                 case HeapTupleMayBeUpdated:
1035                                                         break;
1036
1037                                                 case HeapTupleUpdated:
1038                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1039                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1040                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1041                                                                   (ItemPointer) DatumGetPointer(datum))))
1042                                                         {
1043                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1044                                                                 if (!(TupIsNull(newSlot)))
1045                                                                 {
1046                                                                         slot = newSlot;
1047                                                                         estate->es_useEvalPlan = true;
1048                                                                         goto lmark;
1049                                                                 }
1050                                                         }
1051
1052                                                         /*
1053                                                          * if tuple was deleted or PlanQual failed for
1054                                                          * updated tuple - we must not return this
1055                                                          * tuple!
1056                                                          */
1057                                                         goto lnext;
1058
1059                                                 default:
1060                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1061                                                         return (NULL);
1062                                         }
1063                                 }
1064                         }
1065
1066                         /*
1067                          * Finally create a new "clean" tuple with all junk attributes
1068                          * removed
1069                          */
1070                         newTuple = ExecRemoveJunk(junkfilter, slot);
1071
1072                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1073                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1074                                                                   InvalidBuffer,        /* this tuple has no buffer */
1075                                                                   true);                /* tuple should be pfreed */
1076                 }
1077
1078                 /*
1079                  * now that we have a tuple, do the appropriate thing with it..
1080                  * either return it to the user, add it to a relation someplace,
1081                  * delete it from a relation, or modify some of its attributes.
1082                  */
1083                 switch (operation)
1084                 {
1085                         case CMD_SELECT:
1086                                 ExecSelect(slot,                /* slot containing tuple */
1087                                                    destfunc,    /* destination's tuple-receiver obj */
1088                                                    estate);
1089                                 result = slot;
1090                                 break;
1091
1092                         case CMD_INSERT:
1093                                 ExecInsert(slot, tupleid, estate);
1094                                 result = NULL;
1095                                 break;
1096
1097                         case CMD_DELETE:
1098                                 ExecDelete(slot, tupleid, estate);
1099                                 result = NULL;
1100                                 break;
1101
1102                         case CMD_UPDATE:
1103                                 ExecUpdate(slot, tupleid, estate);
1104                                 result = NULL;
1105                                 break;
1106
1107                         default:
1108                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1109                                 result = NULL;
1110                                 break;
1111                 }
1112
1113                 /*
1114                  * check our tuple count.. if we've processed the proper number
1115                  * then quit, else loop again and process more tuples..
1116                  */
1117                 current_tuple_count++;
1118                 if (numberTuples == current_tuple_count)
1119                         break;
1120         }
1121
1122         /*
1123          * here, result is either a slot containing a tuple in the case of a
1124          * SELECT or NULL otherwise.
1125          */
1126         return result;
1127 }
1128
1129 /* ----------------------------------------------------------------
1130  *              ExecSelect
1131  *
1132  *              SELECTs are easy.. we just pass the tuple to the appropriate
1133  *              print function.  The only complexity is when we do a
1134  *              "SELECT INTO", in which case we insert the tuple into
1135  *              the appropriate relation (note: this is a newly created relation
1136  *              so we don't need to worry about indices or locks.)
1137  * ----------------------------------------------------------------
1138  */
1139 static void
1140 ExecSelect(TupleTableSlot *slot,
1141                    DestReceiver *destfunc,
1142                    EState *estate)
1143 {
1144         HeapTuple       tuple;
1145         TupleDesc       attrtype;
1146
1147         /*
1148          * get the heap tuple out of the tuple table slot
1149          */
1150         tuple = slot->val;
1151         attrtype = slot->ttc_tupleDescriptor;
1152
1153         /*
1154          * insert the tuple into the "into relation"
1155          */
1156         if (estate->es_into_relation_descriptor != NULL)
1157         {
1158                 heap_insert(estate->es_into_relation_descriptor, tuple,
1159                                         estate->es_snapshot->curcid);
1160                 IncrAppended();
1161         }
1162
1163         /*
1164          * send the tuple to the front end (or the screen)
1165          */
1166         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1167         IncrRetrieved();
1168         (estate->es_processed)++;
1169 }
1170
1171 /* ----------------------------------------------------------------
1172  *              ExecInsert
1173  *
1174  *              INSERTs are trickier.. we have to insert the tuple into
1175  *              the base relation and insert appropriate tuples into the
1176  *              index relations.
1177  * ----------------------------------------------------------------
1178  */
1179 static void
1180 ExecInsert(TupleTableSlot *slot,
1181                    ItemPointer tupleid,
1182                    EState *estate)
1183 {
1184         HeapTuple       tuple;
1185         ResultRelInfo *resultRelInfo;
1186         Relation        resultRelationDesc;
1187         int                     numIndices;
1188         Oid                     newId;
1189
1190         /*
1191          * get the heap tuple out of the tuple table slot
1192          */
1193         tuple = slot->val;
1194
1195         /*
1196          * get information on the (current) result relation
1197          */
1198         resultRelInfo = estate->es_result_relation_info;
1199         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1200
1201         /* BEFORE ROW INSERT Triggers */
1202         if (resultRelInfo->ri_TrigDesc &&
1203           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1204         {
1205                 HeapTuple       newtuple;
1206
1207                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1208
1209                 if (newtuple == NULL)   /* "do nothing" */
1210                         return;
1211
1212                 if (newtuple != tuple)  /* modified by Trigger(s) */
1213                 {
1214                         /*
1215                          * Insert modified tuple into tuple table slot, replacing the
1216                          * original.  We assume that it was allocated in per-tuple
1217                          * memory context, and therefore will go away by itself. The
1218                          * tuple table slot should not try to clear it.
1219                          */
1220                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1221                         tuple = newtuple;
1222                 }
1223         }
1224
1225         /*
1226          * Check the constraints of the tuple
1227          */
1228         if (resultRelationDesc->rd_att->constr)
1229                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1230
1231         /*
1232          * insert the tuple
1233          */
1234         newId = heap_insert(resultRelationDesc, tuple,
1235                                                 estate->es_snapshot->curcid);
1236
1237         IncrAppended();
1238         (estate->es_processed)++;
1239         estate->es_lastoid = newId;
1240         setLastTid(&(tuple->t_self));
1241
1242         /*
1243          * process indices
1244          *
1245          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1246          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1247          * field.
1248          */
1249         numIndices = resultRelInfo->ri_NumIndices;
1250         if (numIndices > 0)
1251                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1252
1253         /* AFTER ROW INSERT Triggers */
1254         if (resultRelInfo->ri_TrigDesc)
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                         return;
1304
1305                 case HeapTupleMayBeUpdated:
1306                         break;
1307
1308                 case HeapTupleUpdated:
1309                         if (XactIsoLevel == XACT_SERIALIZABLE)
1310                                 elog(ERROR, "Can't serialize access due to concurrent update");
1311                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1312                         {
1313                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1314                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1315
1316                                 if (!TupIsNull(epqslot))
1317                                 {
1318                                         *tupleid = ctid;
1319                                         goto ldelete;
1320                                 }
1321                         }
1322                         /* tuple already deleted; nothing to do */
1323                         return;
1324
1325                 default:
1326                         elog(ERROR, "Unknown status %u from heap_delete", result);
1327                         return;
1328         }
1329
1330         IncrDeleted();
1331         (estate->es_processed)++;
1332
1333         /*
1334          * Note: Normally one would think that we have to delete index tuples
1335          * associated with the heap tuple now..
1336          *
1337          * ... but in POSTGRES, we have no need to do this because the vacuum
1338          * daemon automatically opens an index scan and deletes index tuples
1339          * when it finds deleted heap tuples. -cim 9/27/89
1340          */
1341
1342         /* AFTER ROW DELETE Triggers */
1343         if (resultRelInfo->ri_TrigDesc)
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                         return;
1438
1439                 case HeapTupleMayBeUpdated:
1440                         break;
1441
1442                 case HeapTupleUpdated:
1443                         if (XactIsoLevel == XACT_SERIALIZABLE)
1444                                 elog(ERROR, "Can't serialize access due to concurrent update");
1445                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1446                         {
1447                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1448                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1449
1450                                 if (!TupIsNull(epqslot))
1451                                 {
1452                                         *tupleid = ctid;
1453                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1454                                         slot = ExecStoreTuple(tuple,
1455                                                                         estate->es_junkFilter->jf_resultSlot,
1456                                                                                   InvalidBuffer, true);
1457                                         goto lreplace;
1458                                 }
1459                         }
1460                         /* tuple already deleted; nothing to do */
1461                         return;
1462
1463                 default:
1464                         elog(ERROR, "Unknown status %u from heap_update", result);
1465                         return;
1466         }
1467
1468         IncrReplaced();
1469         (estate->es_processed)++;
1470
1471         /*
1472          * Note: instead of having to update the old index tuples associated
1473          * with the heap tuple, all we do is form and insert new index tuples.
1474          * This is because UPDATEs are actually DELETEs and INSERTs and index
1475          * tuple deletion is done automagically by the vacuum daemon. All we
1476          * do is insert new index tuples.  -cim 9/27/89
1477          */
1478
1479         /*
1480          * process indices
1481          *
1482          * heap_update updates a tuple in the base relation by invalidating it
1483          * and then inserting a new tuple to the relation.      As a side effect,
1484          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1485          * field.  So we now insert index tuples using the new tupleid stored
1486          * there.
1487          */
1488
1489         numIndices = resultRelInfo->ri_NumIndices;
1490         if (numIndices > 0)
1491                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1492
1493         /* AFTER ROW UPDATE Triggers */
1494         if (resultRelInfo->ri_TrigDesc)
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] = qual;
1524                 }
1525                 MemoryContextSwitchTo(oldContext);
1526         }
1527
1528         /*
1529          * We will use the EState's per-tuple context for evaluating
1530          * constraint expressions (creating it if it's not already there).
1531          */
1532         econtext = GetPerTupleExprContext(estate);
1533
1534         /* Arrange for econtext's scan tuple to be the tuple under test */
1535         econtext->ecxt_scantuple = slot;
1536
1537         /* And evaluate the constraints */
1538         for (i = 0; i < ncheck; i++)
1539         {
1540                 qual = resultRelInfo->ri_ConstraintExprs[i];
1541
1542                 /*
1543                  * NOTE: SQL92 specifies that a NULL result from a constraint
1544                  * expression is not to be treated as a failure.  Therefore, tell
1545                  * ExecQual to return TRUE for NULL.
1546                  */
1547                 if (!ExecQual(qual, econtext, true))
1548                         return check[i].ccname;
1549         }
1550
1551         /* NULL result means no error */
1552         return (char *) NULL;
1553 }
1554
1555 void
1556 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1557                                 TupleTableSlot *slot, EState *estate)
1558 {
1559         Relation        rel = resultRelInfo->ri_RelationDesc;
1560         HeapTuple       tuple = slot->val;
1561         TupleConstr *constr = rel->rd_att->constr;
1562
1563         Assert(constr);
1564
1565         if (constr->has_not_null)
1566         {
1567                 int                     natts = rel->rd_att->natts;
1568                 int                     attrChk;
1569
1570                 for (attrChk = 1; attrChk <= natts; attrChk++)
1571                 {
1572                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1573                                 heap_attisnull(tuple, attrChk))
1574                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1575                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1576                 }
1577         }
1578
1579         if (constr->num_check > 0)
1580         {
1581                 char       *failed;
1582
1583                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1584                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1585                                  caller, failed, RelationGetRelationName(rel));
1586         }
1587 }
1588
1589 /*
1590  * Check a modified tuple to see if we want to process its updated version
1591  * under READ COMMITTED rules.
1592  *
1593  * See backend/executor/README for some info about how this works.
1594  */
1595 TupleTableSlot *
1596 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1597 {
1598         evalPlanQual *epq;
1599         EState     *epqstate;
1600         Relation        relation;
1601         HeapTupleData tuple;
1602         HeapTuple       copyTuple = NULL;
1603         int                     rtsize;
1604         bool            endNode;
1605
1606         Assert(rti != 0);
1607
1608         /*
1609          * find relation containing target tuple
1610          */
1611         if (estate->es_result_relation_info != NULL &&
1612                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1613                 relation = estate->es_result_relation_info->ri_RelationDesc;
1614         else
1615         {
1616                 List       *l;
1617
1618                 relation = NULL;
1619                 foreach(l, estate->es_rowMark)
1620                 {
1621                         if (((execRowMark *) lfirst(l))->rti == rti)
1622                         {
1623                                 relation = ((execRowMark *) lfirst(l))->relation;
1624                                 break;
1625                         }
1626                 }
1627                 if (relation == NULL)
1628                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1629         }
1630
1631         /*
1632          * fetch tid tuple
1633          *
1634          * Loop here to deal with updated or busy tuples
1635          */
1636         tuple.t_self = *tid;
1637         for (;;)
1638         {
1639                 Buffer          buffer;
1640
1641                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1642                 {
1643                         TransactionId xwait = SnapshotDirty->xmax;
1644
1645                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1646                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1647
1648                         /*
1649                          * If tuple is being updated by other transaction then we have
1650                          * to wait for its commit/abort.
1651                          */
1652                         if (TransactionIdIsValid(xwait))
1653                         {
1654                                 ReleaseBuffer(buffer);
1655                                 XactLockTableWait(xwait);
1656                                 continue;
1657                         }
1658
1659                         /*
1660                          * We got tuple - now copy it for use by recheck query.
1661                          */
1662                         copyTuple = heap_copytuple(&tuple);
1663                         ReleaseBuffer(buffer);
1664                         break;
1665                 }
1666
1667                 /*
1668                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1669                  * Note that it's possible to get invalid SnapshotDirty->tid if
1670                  * tuple updated by this transaction. Have we to check this ?
1671                  */
1672                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1673                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1674                 {
1675                         /* updated, so look at the updated copy */
1676                         tuple.t_self = SnapshotDirty->tid;
1677                         continue;
1678                 }
1679
1680                 /*
1681                  * Deleted or updated by this transaction; forget it.
1682                  */
1683                 return NULL;
1684         }
1685
1686         /*
1687          * For UPDATE/DELETE we have to return tid of actual row we're
1688          * executing PQ for.
1689          */
1690         *tid = tuple.t_self;
1691
1692         /*
1693          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1694          */
1695         epq = (evalPlanQual *) estate->es_evalPlanQual;
1696         rtsize = length(estate->es_range_table);
1697         endNode = true;
1698
1699         if (epq != NULL && epq->rti == 0)
1700         {
1701                 /* Top PQ stack entry is idle, so re-use it */
1702                 Assert(!(estate->es_useEvalPlan) &&
1703                            epq->estate.es_evalPlanQual == NULL);
1704                 epq->rti = rti;
1705                 endNode = false;
1706         }
1707
1708         /*
1709          * If this is request for another RTE - Ra, - then we have to check
1710          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1711          * updated again and we have to re-start old execution for Ra and
1712          * forget all what we done after Ra was suspended. Cool? -:))
1713          */
1714         if (epq != NULL && epq->rti != rti &&
1715                 epq->estate.es_evTuple[rti - 1] != NULL)
1716         {
1717                 do
1718                 {
1719                         evalPlanQual *oldepq;
1720
1721                         /* pop previous PlanQual from the stack */
1722                         epqstate = &(epq->estate);
1723                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1724                         Assert(oldepq->rti != 0);
1725                         /* stop execution */
1726                         ExecEndNode(epq->plan, NULL);
1727                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1728                         epqstate->es_tupleTable = NULL;
1729                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1730                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1731                         /* push current PQ to freePQ stack */
1732                         oldepq->free = epq;
1733                         epq = oldepq;
1734                         estate->es_evalPlanQual = (Pointer) epq;
1735                 } while (epq->rti != rti);
1736         }
1737
1738         /*
1739          * If we are requested for another RTE then we have to suspend
1740          * execution of current PlanQual and start execution for new one.
1741          */
1742         if (epq == NULL || epq->rti != rti)
1743         {
1744                 /* try to reuse plan used previously */
1745                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1746
1747                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1748                 {
1749                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1750                         newepq->free = NULL;
1751
1752                         /*
1753                          * Each stack level has its own copy of the plan tree.  This
1754                          * is wasteful, but necessary as long as plan nodes point to
1755                          * exec state nodes rather than vice versa.  Note that
1756                          * copyfuncs.c doesn't attempt to copy the exec state nodes,
1757                          * which is a good thing in this situation.
1758                          */
1759                         newepq->plan = copyObject(estate->es_origPlan);
1760
1761                         /*
1762                          * Init stack level's EState.  We share top level's copy of
1763                          * es_result_relations array and other non-changing status. We
1764                          * need our own tupletable, es_param_exec_vals, and other
1765                          * changeable state.
1766                          */
1767                         epqstate = &(newepq->estate);
1768                         memcpy(epqstate, estate, sizeof(EState));
1769                         epqstate->es_direction = ForwardScanDirection;
1770                         if (estate->es_origPlan->nParamExec > 0)
1771                                 epqstate->es_param_exec_vals = (ParamExecData *)
1772                                         palloc(estate->es_origPlan->nParamExec *
1773                                                    sizeof(ParamExecData));
1774                         epqstate->es_tupleTable = NULL;
1775                         epqstate->es_per_tuple_exprcontext = NULL;
1776
1777                         /*
1778                          * Each epqstate must have its own es_evTupleNull state, but
1779                          * all the stack entries share es_evTuple state.  This allows
1780                          * sub-rechecks to inherit the value being examined by an
1781                          * outer recheck.
1782                          */
1783                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1784                         if (epq == NULL)
1785                         {
1786                                 /* first PQ stack entry */
1787                                 epqstate->es_evTuple = (HeapTuple *)
1788                                         palloc(rtsize * sizeof(HeapTuple));
1789                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1790                         }
1791                         else
1792                         {
1793                                 /* later stack entries share the same storage */
1794                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1795                         }
1796                 }
1797                 else
1798                 {
1799                         /* recycle previously used EState */
1800                         epqstate = &(newepq->estate);
1801                 }
1802                 /* push current PQ to the stack */
1803                 epqstate->es_evalPlanQual = (Pointer) epq;
1804                 epq = newepq;
1805                 estate->es_evalPlanQual = (Pointer) epq;
1806                 epq->rti = rti;
1807                 endNode = false;
1808         }
1809
1810         Assert(epq->rti == rti);
1811         epqstate = &(epq->estate);
1812
1813         /*
1814          * Ok - we're requested for the same RTE.  Unfortunately we still have
1815          * to end and restart execution of the plan, because ExecReScan
1816          * wouldn't ensure that upper plan nodes would reset themselves.  We
1817          * could make that work if insertion of the target tuple were
1818          * integrated with the Param mechanism somehow, so that the upper plan
1819          * nodes know that their children's outputs have changed.
1820          */
1821         if (endNode)
1822         {
1823                 /* stop execution */
1824                 ExecEndNode(epq->plan, NULL);
1825                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1826                 epqstate->es_tupleTable = NULL;
1827         }
1828
1829         /*
1830          * free old RTE' tuple, if any, and store target tuple where
1831          * relation's scan node will see it
1832          */
1833         if (epqstate->es_evTuple[rti - 1] != NULL)
1834                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1835         epqstate->es_evTuple[rti - 1] = copyTuple;
1836
1837         /*
1838          * Initialize for new recheck query; be careful to copy down state
1839          * that might have changed in top EState.
1840          */
1841         epqstate->es_result_relation_info = estate->es_result_relation_info;
1842         epqstate->es_junkFilter = estate->es_junkFilter;
1843         if (estate->es_origPlan->nParamExec > 0)
1844                 memset(epqstate->es_param_exec_vals, 0,
1845                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1846         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1847         epqstate->es_useEvalPlan = false;
1848         Assert(epqstate->es_tupleTable == NULL);
1849         epqstate->es_tupleTable =
1850                 ExecCreateTupleTable(estate->es_tupleTable->size);
1851
1852         ExecInitNode(epq->plan, epqstate, NULL);
1853
1854         return EvalPlanQualNext(estate);
1855 }
1856
1857 static TupleTableSlot *
1858 EvalPlanQualNext(EState *estate)
1859 {
1860         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1861         EState     *epqstate = &(epq->estate);
1862         evalPlanQual *oldepq;
1863         TupleTableSlot *slot;
1864
1865         Assert(epq->rti != 0);
1866
1867 lpqnext:;
1868         slot = ExecProcNode(epq->plan, NULL);
1869
1870         /*
1871          * No more tuples for this PQ. Continue previous one.
1872          */
1873         if (TupIsNull(slot))
1874         {
1875                 /* stop execution */
1876                 ExecEndNode(epq->plan, NULL);
1877                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1878                 epqstate->es_tupleTable = NULL;
1879                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1880                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1881                 /* pop old PQ from the stack */
1882                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1883                 if (oldepq == (evalPlanQual *) NULL)
1884                 {
1885                         epq->rti = 0;           /* this is the first (oldest) */
1886                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1887                         return (NULL);          /* continue Query execution   */
1888                 }
1889                 Assert(oldepq->rti != 0);
1890                 /* push current PQ to freePQ stack */
1891                 oldepq->free = epq;
1892                 epq = oldepq;
1893                 epqstate = &(epq->estate);
1894                 estate->es_evalPlanQual = (Pointer) epq;
1895                 goto lpqnext;
1896         }
1897
1898         return (slot);
1899 }
1900
1901 static void
1902 EndEvalPlanQual(EState *estate)
1903 {
1904         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1905         EState     *epqstate = &(epq->estate);
1906         evalPlanQual *oldepq;
1907
1908         if (epq->rti == 0)                      /* plans already shutdowned */
1909         {
1910                 Assert(epq->estate.es_evalPlanQual == NULL);
1911                 return;
1912         }
1913
1914         for (;;)
1915         {
1916                 /* stop execution */
1917                 ExecEndNode(epq->plan, NULL);
1918                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1919                 epqstate->es_tupleTable = NULL;
1920                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1921                 {
1922                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1923                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1924                 }
1925                 /* pop old PQ from the stack */
1926                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1927                 if (oldepq == (evalPlanQual *) NULL)
1928                 {
1929                         epq->rti = 0;           /* this is the first (oldest) */
1930                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1931                         break;
1932                 }
1933                 Assert(oldepq->rti != 0);
1934                 /* push current PQ to freePQ stack */
1935                 oldepq->free = epq;
1936                 epq = oldepq;
1937                 epqstate = &(epq->estate);
1938                 estate->es_evalPlanQual = (Pointer) epq;
1939         }
1940 }