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  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),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 1.183 2002/11/11 03:02:18 momjian 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 for
 120          * the life of this query, even if it outlives the current command and
 121          * 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
 359          * node, and function RTEs are checked by init_fcache when the
 360          * function is prepared for execution.  Join and special RTEs need no
 361          * checks.
 362          */
 363         if (rte->rtekind != RTE_RELATION)
 364                 return;
 365
 366         relOid = rte->relid;
 367
 368         /*
 369          * userid to check as: current user unless we have a setuid
 370          * indication.
 371          *
 372          * Note: GetUserId() is presently fast enough that there's no harm in
 373          * calling it separately for each RTE.  If that stops being true, we
 374          * could call it once in ExecCheckQueryPerms and pass the userid down
 375          * from there.  But for now, no need for the extra clutter.
 376          */
 377         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 378
 379 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 380
 381         if (rte->checkForRead)
 382         {
 383                 aclcheck_result = CHECK(ACL_SELECT);
 384                 if (aclcheck_result != ACLCHECK_OK)
 385                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 386         }
 387
 388         if (rte->checkForWrite)
 389         {
 390                 /*
 391                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 392                  * Right now we don't distinguish that from true update as far as
 393                  * permissions checks are concerned.
 394                  */
 395                 switch (operation)
 396                 {
 397                         case CMD_INSERT:
 398                                 aclcheck_result = CHECK(ACL_INSERT);
 399                                 break;
 400                         case CMD_SELECT:
 401                         case CMD_UPDATE:
 402                                 aclcheck_result = CHECK(ACL_UPDATE);
 403                                 break;
 404                         case CMD_DELETE:
 405                                 aclcheck_result = CHECK(ACL_DELETE);
 406                                 break;
 407                         default:
 408                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 409                                          operation);
 410                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 411                                 break;
 412                 }
 413                 if (aclcheck_result != ACLCHECK_OK)
 414                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 415         }
 416 }
 417
 418
 419 /* ===============================================================
 420  * ===============================================================
 421                                                  static routines follow
 422  * ===============================================================
 423  * ===============================================================
 424  */
 425
 426 typedef struct execRowMark
 427 {
 428         Relation        relation;
 429         Index           rti;
 430         char            resname[32];
 431 } execRowMark;
 432
 433 typedef struct evalPlanQual
 434 {
 435         Plan       *plan;
 436         Index           rti;
 437         EState          estate;
 438         struct evalPlanQual *free;
 439 } evalPlanQual;
 440
 441 /* ----------------------------------------------------------------
 442  *              InitPlan
 443  *
 444  *              Initializes the query plan: open files, allocate storage
 445  *              and start up the rule manager
 446  * ----------------------------------------------------------------
 447  */
 448 static TupleDesc
 449 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 450 {
 451         List       *rangeTable;
 452         Relation        intoRelationDesc;
 453         TupleDesc       tupType;
 454
 455         /*
 456          * Do permissions checks.
 457          */
 458         ExecCheckQueryPerms(operation, parseTree, plan);
 459
 460         /*
 461          * get information from query descriptor
 462          */
 463         rangeTable = parseTree->rtable;
 464
 465         /*
 466          * initialize the node's execution state
 467          */
 468         estate->es_range_table = rangeTable;
 469
 470         /*
 471          * if there is a result relation, initialize result relation stuff
 472          */
 473         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 474         {
 475                 List       *resultRelations = parseTree->resultRelations;
 476                 int                     numResultRelations;
 477                 ResultRelInfo *resultRelInfos;
 478
 479                 if (resultRelations != NIL)
 480                 {
 481                         /*
 482                          * Multiple result relations (due to inheritance)
 483                          * parseTree->resultRelations identifies them all
 484                          */
 485                         ResultRelInfo *resultRelInfo;
 486
 487                         numResultRelations = length(resultRelations);
 488                         resultRelInfos = (ResultRelInfo *)
 489                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 490                         resultRelInfo = resultRelInfos;
 491                         while (resultRelations != NIL)
 492                         {
 493                                 initResultRelInfo(resultRelInfo,
 494                                                                   lfirsti(resultRelations),
 495                                                                   rangeTable,
 496                                                                   operation);
 497                                 resultRelInfo++;
 498                                 resultRelations = lnext(resultRelations);
 499                         }
 500                 }
 501                 else
 502                 {
 503                         /*
 504                          * Single result relation identified by
 505                          * parseTree->resultRelation
 506                          */
 507                         numResultRelations = 1;
 508                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 509                         initResultRelInfo(resultRelInfos,
 510                                                           parseTree->resultRelation,
 511                                                           rangeTable,
 512                                                           operation);
 513                 }
 514
 515                 estate->es_result_relations = resultRelInfos;
 516                 estate->es_num_result_relations = numResultRelations;
 517                 /* Initialize to first or only result rel */
 518                 estate->es_result_relation_info = resultRelInfos;
 519         }
 520         else
 521         {
 522                 /*
 523                  * if no result relation, then set state appropriately
 524                  */
 525                 estate->es_result_relations = NULL;
 526                 estate->es_num_result_relations = 0;
 527                 estate->es_result_relation_info = NULL;
 528         }
 529
 530         /*
 531          * Have to lock relations selected for update
 532          */
 533         estate->es_rowMark = NIL;
 534         if (parseTree->rowMarks != NIL)
 535         {
 536                 List       *l;
 537
 538                 foreach(l, parseTree->rowMarks)
 539                 {
 540                         Index           rti = lfirsti(l);
 541                         Oid                     relid = getrelid(rti, rangeTable);
 542                         Relation        relation;
 543                         execRowMark *erm;
 544
 545                         relation = heap_open(relid, RowShareLock);
 546                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 547                         erm->relation = relation;
 548                         erm->rti = rti;
 549                         snprintf(erm->resname, 32, "ctid%u", rti);
 550                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 551                 }
 552         }
 553
 554         /*
 555          * initialize the executor "tuple" table.  We need slots for all the
 556          * plan nodes, plus possibly output slots for the junkfilter(s). At
 557          * this point we aren't sure if we need junkfilters, so just add slots
 558          * for them unconditionally.
 559          */
 560         {
 561                 int                     nSlots = ExecCountSlotsNode(plan);
 562
 563                 if (parseTree->resultRelations != NIL)
 564                         nSlots += length(parseTree->resultRelations);
 565                 else
 566                         nSlots += 1;
 567                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 568         }
 569
 570         /* mark EvalPlanQual not active */
 571         estate->es_origPlan = plan;
 572         estate->es_evalPlanQual = NULL;
 573         estate->es_evTuple = NULL;
 574         estate->es_evTupleNull = NULL;
 575         estate->es_useEvalPlan = false;
 576
 577         /*
 578          * initialize the private state information for all the nodes in the
 579          * query tree.  This opens files, allocates storage and leaves us
 580          * ready to start processing tuples.
 581          */
 582         ExecInitNode(plan, estate, NULL);
 583
 584         /*
 585          * Get the tuple descriptor describing the type of tuples to return.
 586          * (this is especially important if we are creating a relation with
 587          * "SELECT INTO")
 588          */
 589         tupType = ExecGetTupType(plan);         /* tuple descriptor */
 590
 591         /*
 592          * Initialize the junk filter if needed. SELECT and INSERT queries
 593          * need a filter if there are any junk attrs in the tlist.      UPDATE and
 594          * DELETE always need one, since there's always a junk 'ctid'
 595          * attribute present --- no need to look first.
 596          */
 597         {
 598                 bool            junk_filter_needed = false;
 599                 List       *tlist;
 600
 601                 switch (operation)
 602                 {
 603                         case CMD_SELECT:
 604                         case CMD_INSERT:
 605                                 foreach(tlist, plan->targetlist)
 606                                 {
 607                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 608
 609                                         if (tle->resdom->resjunk)
 610                                         {
 611                                                 junk_filter_needed = true;
 612                                                 break;
 613                                         }
 614                                 }
 615                                 break;
 616                         case CMD_UPDATE:
 617                         case CMD_DELETE:
 618                                 junk_filter_needed = true;
 619                                 break;
 620                         default:
 621                                 break;
 622                 }
 623
 624                 if (junk_filter_needed)
 625                 {
 626                         /*
 627                          * If there are multiple result relations, each one needs its
 628                          * own junk filter.  Note this is only possible for
 629                          * UPDATE/DELETE, so we can't be fooled by some needing a
 630                          * filter and some not.
 631                          */
 632                         if (parseTree->resultRelations != NIL)
 633                         {
 634                                 List       *subplans;
 635                                 ResultRelInfo *resultRelInfo;
 636
 637                                 /* Top plan had better be an Append here. */
 638                                 Assert(IsA(plan, Append));
 639                                 Assert(((Append *) plan)->isTarget);
 640                                 subplans = ((Append *) plan)->appendplans;
 641                                 Assert(length(subplans) == estate->es_num_result_relations);
 642                                 resultRelInfo = estate->es_result_relations;
 643                                 while (subplans != NIL)
 644                                 {
 645                                         Plan       *subplan = (Plan *) lfirst(subplans);
 646                                         JunkFilter *j;
 647
 648                                         j = ExecInitJunkFilter(subplan->targetlist,
 649                                                                                    ExecGetTupType(subplan),
 650                                                           ExecAllocTableSlot(estate->es_tupleTable));
 651                                         resultRelInfo->ri_junkFilter = j;
 652                                         resultRelInfo++;
 653                                         subplans = lnext(subplans);
 654                                 }
 655
 656                                 /*
 657                                  * Set active junkfilter too; at this point ExecInitAppend
 658                                  * has already selected an active result relation...
 659                                  */
 660                                 estate->es_junkFilter =
 661                                         estate->es_result_relation_info->ri_junkFilter;
 662                         }
 663                         else
 664                         {
 665                                 /* Normal case with just one JunkFilter */
 666                                 JunkFilter *j;
 667
 668                                 j = ExecInitJunkFilter(plan->targetlist,
 669                                                                            tupType,
 670                                                           ExecAllocTableSlot(estate->es_tupleTable));
 671                                 estate->es_junkFilter = j;
 672                                 if (estate->es_result_relation_info)
 673                                         estate->es_result_relation_info->ri_junkFilter = j;
 674
 675                                 /* For SELECT, want to return the cleaned tuple type */
 676                                 if (operation == CMD_SELECT)
 677                                         tupType = j->jf_cleanTupType;
 678                         }
 679                 }
 680                 else
 681                         estate->es_junkFilter = NULL;
 682         }
 683
 684         /*
 685          * initialize the "into" relation
 686          */
 687         intoRelationDesc = (Relation) NULL;
 688
 689         if (operation == CMD_SELECT)
 690         {
 691                 if (!parseTree->isPortal)
 692                 {
 693                         /*
 694                          * a select into table --- need to create the "into" table
 695                          */
 696                         if (parseTree->into != NULL)
 697                         {
 698                                 char       *intoName;
 699                                 Oid                     namespaceId;
 700                                 AclResult       aclresult;
 701                                 Oid                     intoRelationId;
 702                                 TupleDesc       tupdesc;
 703
 704                                 /*
 705                                  * find namespace to create in, check permissions
 706                                  */
 707                                 intoName = parseTree->into->relname;
 708                                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 709
 710                                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 711                                                                                                   ACL_CREATE);
 712                                 if (aclresult != ACLCHECK_OK)
 713                                         aclcheck_error(aclresult,
 714                                                                    get_namespace_name(namespaceId));
 715
 716                                 /*
 717                                  * have to copy tupType to get rid of constraints
 718                                  */
 719                                 tupdesc = CreateTupleDescCopy(tupType);
 720
 721                                 /*
 722                                  * Formerly we forced the output table to have OIDs, but
 723                                  * as of 7.3 it will not have OIDs, because it's too late
 724                                  * here to change the tupdescs of the already-initialized
 725                                  * plan tree.  (Perhaps we could recurse and change them
 726                                  * all, but it's not really worth the trouble IMHO...)
 727                                  */
 728
 729                                 intoRelationId =
 730                                         heap_create_with_catalog(intoName,
 731                                                                                          namespaceId,
 732                                                                                          tupdesc,
 733                                                                                          RELKIND_RELATION,
 734                                                                                          false,
 735                                                                                          ATEOXACTNOOP,
 736                                                                                          allowSystemTableMods);
 737
 738                                 FreeTupleDesc(tupdesc);
 739
 740                                 /*
 741                                  * Advance command counter so that the newly-created
 742                                  * relation's catalog tuples will be visible to heap_open.
 743                                  */
 744                                 CommandCounterIncrement();
 745
 746                                 /*
 747                                  * If necessary, create a TOAST table for the into
 748                                  * relation. Note that AlterTableCreateToastTable ends
 749                                  * with CommandCounterIncrement(), so that the TOAST table
 750                                  * will be visible for insertion.
 751                                  */
 752                                 AlterTableCreateToastTable(intoRelationId, true);
 753
 754                                 intoRelationDesc = heap_open(intoRelationId,
 755                                                                                          AccessExclusiveLock);
 756                         }
 757                 }
 758         }
 759
 760         estate->es_into_relation_descriptor = intoRelationDesc;
 761
 762         return tupType;
 763 }
 764
 765 /*
 766  * Initialize ResultRelInfo data for one result relation
 767  */
 768 static void
 769 initResultRelInfo(ResultRelInfo *resultRelInfo,
 770                                   Index resultRelationIndex,
 771                                   List *rangeTable,
 772                                   CmdType operation)
 773 {
 774         Oid                     resultRelationOid;
 775         Relation        resultRelationDesc;
 776
 777         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 778         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 779
 780         switch (resultRelationDesc->rd_rel->relkind)
 781         {
 782                 case RELKIND_SEQUENCE:
 783                         elog(ERROR, "You can't change sequence relation %s",
 784                                  RelationGetRelationName(resultRelationDesc));
 785                         break;
 786                 case RELKIND_TOASTVALUE:
 787                         elog(ERROR, "You can't change toast relation %s",
 788                                  RelationGetRelationName(resultRelationDesc));
 789                         break;
 790                 case RELKIND_VIEW:
 791                         elog(ERROR, "You can't change view relation %s",
 792                                  RelationGetRelationName(resultRelationDesc));
 793                         break;
 794         }
 795
 796         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 797         resultRelInfo->type = T_ResultRelInfo;
 798         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 799         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 800         resultRelInfo->ri_NumIndices = 0;
 801         resultRelInfo->ri_IndexRelationDescs = NULL;
 802         resultRelInfo->ri_IndexRelationInfo = NULL;
 803         /* make a copy so as not to depend on relcache info not changing... */
 804         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 805         resultRelInfo->ri_TrigFunctions = NULL;
 806         resultRelInfo->ri_ConstraintExprs = NULL;
 807         resultRelInfo->ri_junkFilter = NULL;
 808
 809         /*
 810          * If there are indices on the result relation, open them and save
 811          * descriptors in the result relation info, so that we can add new
 812          * index entries for the tuples we add/update.  We need not do this
 813          * for a DELETE, however, since deletion doesn't affect indexes.
 814          */
 815         if (resultRelationDesc->rd_rel->relhasindex &&
 816                 operation != CMD_DELETE)
 817                 ExecOpenIndices(resultRelInfo);
 818 }
 819
 820 /* ----------------------------------------------------------------
 821  *              EndPlan
 822  *
 823  *              Cleans up the query plan -- closes files and free up storages
 824  * ----------------------------------------------------------------
 825  */
 826 static void
 827 EndPlan(Plan *plan, EState *estate)
 828 {
 829         ResultRelInfo *resultRelInfo;
 830         int                     i;
 831         List       *l;
 832
 833         /*
 834          * shut down any PlanQual processing we were doing
 835          */
 836         if (estate->es_evalPlanQual != NULL)
 837                 EndEvalPlanQual(estate);
 838
 839         /*
 840          * shut down the node-type-specific query processing
 841          */
 842         ExecEndNode(plan, NULL);
 843
 844         /*
 845          * destroy the executor "tuple" table.
 846          */
 847         ExecDropTupleTable(estate->es_tupleTable, true);
 848         estate->es_tupleTable = NULL;
 849
 850         /*
 851          * close the result relation(s) if any, but hold locks until xact
 852          * commit.      Also clean up junkfilters if present.
 853          */
 854         resultRelInfo = estate->es_result_relations;
 855         for (i = estate->es_num_result_relations; i > 0; i--)
 856         {
 857                 /* Close indices and then the relation itself */
 858                 ExecCloseIndices(resultRelInfo);
 859                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 860                 /* Delete the junkfilter if any */
 861                 if (resultRelInfo->ri_junkFilter != NULL)
 862                         ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
 863                 resultRelInfo++;
 864         }
 865
 866         /*
 867          * close the "into" relation if necessary, again keeping lock
 868          */
 869         if (estate->es_into_relation_descriptor != NULL)
 870                 heap_close(estate->es_into_relation_descriptor, NoLock);
 871
 872         /*
 873          * There might be a junkfilter without a result relation.
 874          */
 875         if (estate->es_num_result_relations == 0 &&
 876                 estate->es_junkFilter != NULL)
 877         {
 878                 ExecFreeJunkFilter(estate->es_junkFilter);
 879                 estate->es_junkFilter = NULL;
 880         }
 881
 882         /*
 883          * close any relations selected FOR UPDATE, again keeping locks
 884          */
 885         foreach(l, estate->es_rowMark)
 886         {
 887                 execRowMark *erm = lfirst(l);
 888
 889                 heap_close(erm->relation, NoLock);
 890         }
 891 }
 892
 893 /* ----------------------------------------------------------------
 894  *              ExecutePlan
 895  *
 896  *              processes the query plan to retrieve 'numberTuples' tuples in the
 897  *              direction specified.
 898  *              Retrieves all tuples if numberTuples is 0
 899  *
 900  *              result is either a slot containing the last tuple in the case
 901  *              of a SELECT or NULL otherwise.
 902  *
 903  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 904  * user can see it
 905  * ----------------------------------------------------------------
 906  */
 907 static TupleTableSlot *
 908 ExecutePlan(EState *estate,
 909                         Plan *plan,
 910                         CmdType operation,
 911                         long numberTuples,
 912                         ScanDirection direction,
 913                         DestReceiver *destfunc)
 914 {
 915         JunkFilter *junkfilter;
 916         TupleTableSlot *slot;
 917         ItemPointer tupleid = NULL;
 918         ItemPointerData tuple_ctid;
 919         long            current_tuple_count;
 920         TupleTableSlot *result;
 921
 922         /*
 923          * initialize local variables
 924          */
 925         slot = NULL;
 926         current_tuple_count = 0;
 927         result = NULL;
 928
 929         /*
 930          * Set the direction.
 931          */
 932         estate->es_direction = direction;
 933
 934         /*
 935          * Loop until we've processed the proper number of tuples from the
 936          * plan.
 937          */
 938
 939         for (;;)
 940         {
 941                 /* Reset the per-output-tuple exprcontext */
 942                 ResetPerTupleExprContext(estate);
 943
 944                 /*
 945                  * Execute the plan and obtain a tuple
 946                  */
 947 lnext:  ;
 948                 if (estate->es_useEvalPlan)
 949                 {
 950                         slot = EvalPlanQualNext(estate);
 951                         if (TupIsNull(slot))
 952                                 slot = ExecProcNode(plan, NULL);
 953                 }
 954                 else
 955                         slot = ExecProcNode(plan, NULL);
 956
 957                 /*
 958                  * if the tuple is null, then we assume there is nothing more to
 959                  * process so we just return null...
 960                  */
 961                 if (TupIsNull(slot))
 962                 {
 963                         result = NULL;
 964                         break;
 965                 }
 966
 967                 /*
 968                  * if we have a junk filter, then project a new tuple with the
 969                  * junk removed.
 970                  *
 971                  * Store this new "clean" tuple in the junkfilter's resultSlot.
 972                  * (Formerly, we stored it back over the "dirty" tuple, which is
 973                  * WRONG because that tuple slot has the wrong descriptor.)
 974                  *
 975                  * Also, extract all the junk information we need.
 976                  */
 977                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
 978                 {
 979                         Datum           datum;
 980                         HeapTuple       newTuple;
 981                         bool            isNull;
 982
 983                         /*
 984                          * extract the 'ctid' junk attribute.
 985                          */
 986                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 987                         {
 988                                 if (!ExecGetJunkAttribute(junkfilter,
 989                                                                                   slot,
 990                                                                                   "ctid",
 991                                                                                   &datum,
 992                                                                                   &isNull))
 993                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
 994
 995                                 /* shouldn't ever get a null result... */
 996                                 if (isNull)
 997                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
 998
 999                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1000                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1001                                                                                  * ctid!! */
1002                                 tupleid = &tuple_ctid;
1003                         }
1004                         else if (estate->es_rowMark != NIL)
1005                         {
1006                                 List       *l;
1007
1008                 lmark:  ;
1009                                 foreach(l, estate->es_rowMark)
1010                                 {
1011                                         execRowMark *erm = lfirst(l);
1012                                         Buffer          buffer;
1013                                         HeapTupleData tuple;
1014                                         TupleTableSlot *newSlot;
1015                                         int                     test;
1016
1017                                         if (!ExecGetJunkAttribute(junkfilter,
1018                                                                                           slot,
1019                                                                                           erm->resname,
1020                                                                                           &datum,
1021                                                                                           &isNull))
1022                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1023                                                          erm->resname);
1024
1025                                         /* shouldn't ever get a null result... */
1026                                         if (isNull)
1027                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1028                                                          erm->resname);
1029
1030                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1031                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1032                                                                                         estate->es_snapshot->curcid);
1033                                         ReleaseBuffer(buffer);
1034                                         switch (test)
1035                                         {
1036                                                 case HeapTupleSelfUpdated:
1037                                                         /* treat it as deleted; do not process */
1038                                                         goto lnext;
1039
1040                                                 case HeapTupleMayBeUpdated:
1041                                                         break;
1042
1043                                                 case HeapTupleUpdated:
1044                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1045                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1046                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1047                                                                   (ItemPointer) DatumGetPointer(datum))))
1048                                                         {
1049                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1050                                                                 if (!(TupIsNull(newSlot)))
1051                                                                 {
1052                                                                         slot = newSlot;
1053                                                                         estate->es_useEvalPlan = true;
1054                                                                         goto lmark;
1055                                                                 }
1056                                                         }
1057
1058                                                         /*
1059                                                          * if tuple was deleted or PlanQual failed for
1060                                                          * updated tuple - we must not return this
1061                                                          * tuple!
1062                                                          */
1063                                                         goto lnext;
1064
1065                                                 default:
1066                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1067                                                         return (NULL);
1068                                         }
1069                                 }
1070                         }
1071
1072                         /*
1073                          * Finally create a new "clean" tuple with all junk attributes
1074                          * removed
1075                          */
1076                         newTuple = ExecRemoveJunk(junkfilter, slot);
1077
1078                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1079                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1080                                                                   InvalidBuffer,                /* this tuple has no
1081                                                                                                                  * buffer */
1082                                                                   true);                /* tuple should be pfreed */
1083                 }
1084
1085                 /*
1086                  * now that we have a tuple, do the appropriate thing with it..
1087                  * either return it to the user, add it to a relation someplace,
1088                  * delete it from a relation, or modify some of its attributes.
1089                  */
1090                 switch (operation)
1091                 {
1092                         case CMD_SELECT:
1093                                 ExecSelect(slot,        /* slot containing tuple */
1094                                                    destfunc,    /* destination's tuple-receiver
1095                                                                                  * obj */
1096                                                    estate);
1097                                 result = slot;
1098                                 break;
1099
1100                         case CMD_INSERT:
1101                                 ExecInsert(slot, tupleid, estate);
1102                                 result = NULL;
1103                                 break;
1104
1105                         case CMD_DELETE:
1106                                 ExecDelete(slot, tupleid, estate);
1107                                 result = NULL;
1108                                 break;
1109
1110                         case CMD_UPDATE:
1111                                 ExecUpdate(slot, tupleid, estate);
1112                                 result = NULL;
1113                                 break;
1114
1115                         default:
1116                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1117                                 result = NULL;
1118                                 break;
1119                 }
1120
1121                 /*
1122                  * check our tuple count.. if we've processed the proper number
1123                  * then quit, else loop again and process more tuples..
1124                  */
1125                 current_tuple_count++;
1126                 if (numberTuples == current_tuple_count)
1127                         break;
1128         }
1129
1130         /*
1131          * here, result is either a slot containing a tuple in the case of a
1132          * SELECT or NULL otherwise.
1133          */
1134         return result;
1135 }
1136
1137 /* ----------------------------------------------------------------
1138  *              ExecSelect
1139  *
1140  *              SELECTs are easy.. we just pass the tuple to the appropriate
1141  *              print function.  The only complexity is when we do a
1142  *              "SELECT INTO", in which case we insert the tuple into
1143  *              the appropriate relation (note: this is a newly created relation
1144  *              so we don't need to worry about indices or locks.)
1145  * ----------------------------------------------------------------
1146  */
1147 static void
1148 ExecSelect(TupleTableSlot *slot,
1149                    DestReceiver *destfunc,
1150                    EState *estate)
1151 {
1152         HeapTuple       tuple;
1153         TupleDesc       attrtype;
1154
1155         /*
1156          * get the heap tuple out of the tuple table slot
1157          */
1158         tuple = slot->val;
1159         attrtype = slot->ttc_tupleDescriptor;
1160
1161         /*
1162          * insert the tuple into the "into relation"
1163          */
1164         if (estate->es_into_relation_descriptor != NULL)
1165         {
1166                 heap_insert(estate->es_into_relation_descriptor, tuple,
1167                                         estate->es_snapshot->curcid);
1168                 IncrAppended();
1169         }
1170
1171         /*
1172          * send the tuple to the front end (or the screen)
1173          */
1174         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1175         IncrRetrieved();
1176         (estate->es_processed)++;
1177 }
1178
1179 /* ----------------------------------------------------------------
1180  *              ExecInsert
1181  *
1182  *              INSERTs are trickier.. we have to insert the tuple into
1183  *              the base relation and insert appropriate tuples into the
1184  *              index relations.
1185  * ----------------------------------------------------------------
1186  */
1187 static void
1188 ExecInsert(TupleTableSlot *slot,
1189                    ItemPointer tupleid,
1190                    EState *estate)
1191 {
1192         HeapTuple       tuple;
1193         ResultRelInfo *resultRelInfo;
1194         Relation        resultRelationDesc;
1195         int                     numIndices;
1196         Oid                     newId;
1197
1198         /*
1199          * get the heap tuple out of the tuple table slot
1200          */
1201         tuple = slot->val;
1202
1203         /*
1204          * get information on the (current) result relation
1205          */
1206         resultRelInfo = estate->es_result_relation_info;
1207         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1208
1209         /* BEFORE ROW INSERT Triggers */
1210         if (resultRelInfo->ri_TrigDesc &&
1211           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1212         {
1213                 HeapTuple       newtuple;
1214
1215                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1216
1217                 if (newtuple == NULL)   /* "do nothing" */
1218                         return;
1219
1220                 if (newtuple != tuple)  /* modified by Trigger(s) */
1221                 {
1222                         /*
1223                          * Insert modified tuple into tuple table slot, replacing the
1224                          * original.  We assume that it was allocated in per-tuple
1225                          * memory context, and therefore will go away by itself. The
1226                          * tuple table slot should not try to clear it.
1227                          */
1228                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1229                         tuple = newtuple;
1230                 }
1231         }
1232
1233         /*
1234          * Check the constraints of the tuple
1235          */
1236         if (resultRelationDesc->rd_att->constr)
1237                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1238
1239         /*
1240          * insert the tuple
1241          */
1242         newId = heap_insert(resultRelationDesc, tuple,
1243                                                 estate->es_snapshot->curcid);
1244
1245         IncrAppended();
1246         (estate->es_processed)++;
1247         estate->es_lastoid = newId;
1248         setLastTid(&(tuple->t_self));
1249
1250         /*
1251          * process indices
1252          *
1253          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1254          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1255          * field.
1256          */
1257         numIndices = resultRelInfo->ri_NumIndices;
1258         if (numIndices > 0)
1259                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1260
1261         /* AFTER ROW INSERT Triggers */
1262         if (resultRelInfo->ri_TrigDesc)
1263                 ExecARInsertTriggers(estate, resultRelInfo, tuple);
1264 }
1265
1266 /* ----------------------------------------------------------------
1267  *              ExecDelete
1268  *
1269  *              DELETE is like UPDATE, we delete the tuple and its
1270  *              index tuples.
1271  * ----------------------------------------------------------------
1272  */
1273 static void
1274 ExecDelete(TupleTableSlot *slot,
1275                    ItemPointer tupleid,
1276                    EState *estate)
1277 {
1278         ResultRelInfo *resultRelInfo;
1279         Relation        resultRelationDesc;
1280         ItemPointerData ctid;
1281         int                     result;
1282
1283         /*
1284          * get information on the (current) result relation
1285          */
1286         resultRelInfo = estate->es_result_relation_info;
1287         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1288
1289         /* BEFORE ROW DELETE Triggers */
1290         if (resultRelInfo->ri_TrigDesc &&
1291           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1292         {
1293                 bool            dodelete;
1294
1295                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1296
1297                 if (!dodelete)                  /* "do nothing" */
1298                         return;
1299         }
1300
1301         /*
1302          * delete the tuple
1303          */
1304 ldelete:;
1305         result = heap_delete(resultRelationDesc, tupleid,
1306                                                  &ctid,
1307                                                  estate->es_snapshot->curcid);
1308         switch (result)
1309         {
1310                 case HeapTupleSelfUpdated:
1311                         /* already deleted by self; nothing to do */
1312                         return;
1313
1314                 case HeapTupleMayBeUpdated:
1315                         break;
1316
1317                 case HeapTupleUpdated:
1318                         if (XactIsoLevel == XACT_SERIALIZABLE)
1319                                 elog(ERROR, "Can't serialize access due to concurrent update");
1320                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1321                         {
1322                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1323                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1324
1325                                 if (!TupIsNull(epqslot))
1326                                 {
1327                                         *tupleid = ctid;
1328                                         goto ldelete;
1329                                 }
1330                         }
1331                         /* tuple already deleted; nothing to do */
1332                         return;
1333
1334                 default:
1335                         elog(ERROR, "Unknown status %u from heap_delete", result);
1336                         return;
1337         }
1338
1339         IncrDeleted();
1340         (estate->es_processed)++;
1341
1342         /*
1343          * Note: Normally one would think that we have to delete index tuples
1344          * associated with the heap tuple now..
1345          *
1346          * ... but in POSTGRES, we have no need to do this because the vacuum
1347          * daemon automatically opens an index scan and deletes index tuples
1348          * when it finds deleted heap tuples. -cim 9/27/89
1349          */
1350
1351         /* AFTER ROW DELETE Triggers */
1352         if (resultRelInfo->ri_TrigDesc)
1353                 ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1354 }
1355
1356 /* ----------------------------------------------------------------
1357  *              ExecUpdate
1358  *
1359  *              note: we can't run UPDATE queries with transactions
1360  *              off because UPDATEs are actually INSERTs and our
1361  *              scan will mistakenly loop forever, updating the tuple
1362  *              it just inserted..      This should be fixed but until it
1363  *              is, we don't want to get stuck in an infinite loop
1364  *              which corrupts your database..
1365  * ----------------------------------------------------------------
1366  */
1367 static void
1368 ExecUpdate(TupleTableSlot *slot,
1369                    ItemPointer tupleid,
1370                    EState *estate)
1371 {
1372         HeapTuple       tuple;
1373         ResultRelInfo *resultRelInfo;
1374         Relation        resultRelationDesc;
1375         ItemPointerData ctid;
1376         int                     result;
1377         int                     numIndices;
1378
1379         /*
1380          * abort the operation if not running transactions
1381          */
1382         if (IsBootstrapProcessingMode())
1383         {
1384                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1385                 return;
1386         }
1387
1388         /*
1389          * get the heap tuple out of the tuple table slot
1390          */
1391         tuple = slot->val;
1392
1393         /*
1394          * get information on the (current) result relation
1395          */
1396         resultRelInfo = estate->es_result_relation_info;
1397         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1398
1399         /* BEFORE ROW UPDATE Triggers */
1400         if (resultRelInfo->ri_TrigDesc &&
1401           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1402         {
1403                 HeapTuple       newtuple;
1404
1405                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1406                                                                                 tupleid, tuple);
1407
1408                 if (newtuple == NULL)   /* "do nothing" */
1409                         return;
1410
1411                 if (newtuple != tuple)  /* modified by Trigger(s) */
1412                 {
1413                         /*
1414                          * Insert modified tuple into tuple table slot, replacing the
1415                          * original.  We assume that it was allocated in per-tuple
1416                          * memory context, and therefore will go away by itself. The
1417                          * tuple table slot should not try to clear it.
1418                          */
1419                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1420                         tuple = newtuple;
1421                 }
1422         }
1423
1424         /*
1425          * Check the constraints of the tuple
1426          *
1427          * If we generate a new candidate tuple after EvalPlanQual testing, we
1428          * must loop back here and recheck constraints.  (We don't need to
1429          * redo triggers, however.      If there are any BEFORE triggers then
1430          * trigger.c will have done mark4update to lock the correct tuple, so
1431          * there's no need to do them again.)
1432          */
1433 lreplace:;
1434         if (resultRelationDesc->rd_att->constr)
1435                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1436
1437         /*
1438          * replace the heap tuple
1439          */
1440         result = heap_update(resultRelationDesc, tupleid, tuple,
1441                                                  &ctid,
1442                                                  estate->es_snapshot->curcid);
1443         switch (result)
1444         {
1445                 case HeapTupleSelfUpdated:
1446                         /* already deleted by self; nothing to do */
1447                         return;
1448
1449                 case HeapTupleMayBeUpdated:
1450                         break;
1451
1452                 case HeapTupleUpdated:
1453                         if (XactIsoLevel == XACT_SERIALIZABLE)
1454                                 elog(ERROR, "Can't serialize access due to concurrent update");
1455                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1456                         {
1457                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1458                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1459
1460                                 if (!TupIsNull(epqslot))
1461                                 {
1462                                         *tupleid = ctid;
1463                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1464                                         slot = ExecStoreTuple(tuple,
1465                                                                         estate->es_junkFilter->jf_resultSlot,
1466                                                                                   InvalidBuffer, true);
1467                                         goto lreplace;
1468                                 }
1469                         }
1470                         /* tuple already deleted; nothing to do */
1471                         return;
1472
1473                 default:
1474                         elog(ERROR, "Unknown status %u from heap_update", result);
1475                         return;
1476         }
1477
1478         IncrReplaced();
1479         (estate->es_processed)++;
1480
1481         /*
1482          * Note: instead of having to update the old index tuples associated
1483          * with the heap tuple, all we do is form and insert new index tuples.
1484          * This is because UPDATEs are actually DELETEs and INSERTs and index
1485          * tuple deletion is done automagically by the vacuum daemon. All we
1486          * do is insert new index tuples.  -cim 9/27/89
1487          */
1488
1489         /*
1490          * process indices
1491          *
1492          * heap_update updates a tuple in the base relation by invalidating it
1493          * and then inserting a new tuple to the relation.      As a side effect,
1494          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1495          * field.  So we now insert index tuples using the new tupleid stored
1496          * there.
1497          */
1498
1499         numIndices = resultRelInfo->ri_NumIndices;
1500         if (numIndices > 0)
1501                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1502
1503         /* AFTER ROW UPDATE Triggers */
1504         if (resultRelInfo->ri_TrigDesc)
1505                 ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1506 }
1507
1508 static char *
1509 ExecRelCheck(ResultRelInfo *resultRelInfo,
1510                          TupleTableSlot *slot, EState *estate)
1511 {
1512         Relation        rel = resultRelInfo->ri_RelationDesc;
1513         int                     ncheck = rel->rd_att->constr->num_check;
1514         ConstrCheck *check = rel->rd_att->constr->check;
1515         ExprContext *econtext;
1516         MemoryContext oldContext;
1517         List       *qual;
1518         int                     i;
1519
1520         /*
1521          * If first time through for this result relation, build expression
1522          * nodetrees for rel's constraint expressions.  Keep them in the
1523          * per-query memory context so they'll survive throughout the query.
1524          */
1525         if (resultRelInfo->ri_ConstraintExprs == NULL)
1526         {
1527                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1528                 resultRelInfo->ri_ConstraintExprs =
1529                         (List **) palloc(ncheck * sizeof(List *));
1530                 for (i = 0; i < ncheck; i++)
1531                 {
1532                         qual = (List *) stringToNode(check[i].ccbin);
1533                         resultRelInfo->ri_ConstraintExprs[i] = qual;
1534                 }
1535                 MemoryContextSwitchTo(oldContext);
1536         }
1537
1538         /*
1539          * We will use the EState's per-tuple context for evaluating
1540          * constraint expressions (creating it if it's not already there).
1541          */
1542         econtext = GetPerTupleExprContext(estate);
1543
1544         /* Arrange for econtext's scan tuple to be the tuple under test */
1545         econtext->ecxt_scantuple = slot;
1546
1547         /* And evaluate the constraints */
1548         for (i = 0; i < ncheck; i++)
1549         {
1550                 qual = resultRelInfo->ri_ConstraintExprs[i];
1551
1552                 /*
1553                  * NOTE: SQL92 specifies that a NULL result from a constraint
1554                  * expression is not to be treated as a failure.  Therefore, tell
1555                  * ExecQual to return TRUE for NULL.
1556                  */
1557                 if (!ExecQual(qual, econtext, true))
1558                         return check[i].ccname;
1559         }
1560
1561         /* NULL result means no error */
1562         return (char *) NULL;
1563 }
1564
1565 void
1566 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1567                                 TupleTableSlot *slot, EState *estate)
1568 {
1569         Relation        rel = resultRelInfo->ri_RelationDesc;
1570         HeapTuple       tuple = slot->val;
1571         TupleConstr *constr = rel->rd_att->constr;
1572
1573         Assert(constr);
1574
1575         if (constr->has_not_null)
1576         {
1577                 int                     natts = rel->rd_att->natts;
1578                 int                     attrChk;
1579
1580                 for (attrChk = 1; attrChk <= natts; attrChk++)
1581                 {
1582                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1583                                 heap_attisnull(tuple, attrChk))
1584                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1585                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1586                 }
1587         }
1588
1589         if (constr->num_check > 0)
1590         {
1591                 char       *failed;
1592
1593                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1594                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1595                                  caller, failed, RelationGetRelationName(rel));
1596         }
1597 }
1598
1599 /*
1600  * Check a modified tuple to see if we want to process its updated version
1601  * under READ COMMITTED rules.
1602  *
1603  * See backend/executor/README for some info about how this works.
1604  */
1605 TupleTableSlot *
1606 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1607 {
1608         evalPlanQual *epq;
1609         EState     *epqstate;
1610         Relation        relation;
1611         HeapTupleData tuple;
1612         HeapTuple       copyTuple = NULL;
1613         int                     rtsize;
1614         bool            endNode;
1615
1616         Assert(rti != 0);
1617
1618         /*
1619          * find relation containing target tuple
1620          */
1621         if (estate->es_result_relation_info != NULL &&
1622                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1623                 relation = estate->es_result_relation_info->ri_RelationDesc;
1624         else
1625         {
1626                 List       *l;
1627
1628                 relation = NULL;
1629                 foreach(l, estate->es_rowMark)
1630                 {
1631                         if (((execRowMark *) lfirst(l))->rti == rti)
1632                         {
1633                                 relation = ((execRowMark *) lfirst(l))->relation;
1634                                 break;
1635                         }
1636                 }
1637                 if (relation == NULL)
1638                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1639         }
1640
1641         /*
1642          * fetch tid tuple
1643          *
1644          * Loop here to deal with updated or busy tuples
1645          */
1646         tuple.t_self = *tid;
1647         for (;;)
1648         {
1649                 Buffer          buffer;
1650
1651                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1652                 {
1653                         TransactionId xwait = SnapshotDirty->xmax;
1654
1655                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1656                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1657
1658                         /*
1659                          * If tuple is being updated by other transaction then we have
1660                          * to wait for its commit/abort.
1661                          */
1662                         if (TransactionIdIsValid(xwait))
1663                         {
1664                                 ReleaseBuffer(buffer);
1665                                 XactLockTableWait(xwait);
1666                                 continue;
1667                         }
1668
1669                         /*
1670                          * We got tuple - now copy it for use by recheck query.
1671                          */
1672                         copyTuple = heap_copytuple(&tuple);
1673                         ReleaseBuffer(buffer);
1674                         break;
1675                 }
1676
1677                 /*
1678                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1679                  * Note that it's possible to get invalid SnapshotDirty->tid if
1680                  * tuple updated by this transaction. Have we to check this ?
1681                  */
1682                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1683                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1684                 {
1685                         /* updated, so look at the updated copy */
1686                         tuple.t_self = SnapshotDirty->tid;
1687                         continue;
1688                 }
1689
1690                 /*
1691                  * Deleted or updated by this transaction; forget it.
1692                  */
1693                 return NULL;
1694         }
1695
1696         /*
1697          * For UPDATE/DELETE we have to return tid of actual row we're
1698          * executing PQ for.
1699          */
1700         *tid = tuple.t_self;
1701
1702         /*
1703          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1704          */
1705         epq = (evalPlanQual *) estate->es_evalPlanQual;
1706         rtsize = length(estate->es_range_table);
1707         endNode = true;
1708
1709         if (epq != NULL && epq->rti == 0)
1710         {
1711                 /* Top PQ stack entry is idle, so re-use it */
1712                 Assert(!(estate->es_useEvalPlan) &&
1713                            epq->estate.es_evalPlanQual == NULL);
1714                 epq->rti = rti;
1715                 endNode = false;
1716         }
1717
1718         /*
1719          * If this is request for another RTE - Ra, - then we have to check
1720          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1721          * updated again and we have to re-start old execution for Ra and
1722          * forget all what we done after Ra was suspended. Cool? -:))
1723          */
1724         if (epq != NULL && epq->rti != rti &&
1725                 epq->estate.es_evTuple[rti - 1] != NULL)
1726         {
1727                 do
1728                 {
1729                         evalPlanQual *oldepq;
1730
1731                         /* pop previous PlanQual from the stack */
1732                         epqstate = &(epq->estate);
1733                         oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1734                         Assert(oldepq->rti != 0);
1735                         /* stop execution */
1736                         ExecEndNode(epq->plan, NULL);
1737                         ExecDropTupleTable(epqstate->es_tupleTable, true);
1738                         epqstate->es_tupleTable = NULL;
1739                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1740                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1741                         /* push current PQ to freePQ stack */
1742                         oldepq->free = epq;
1743                         epq = oldepq;
1744                         estate->es_evalPlanQual = (Pointer) epq;
1745                 } while (epq->rti != rti);
1746         }
1747
1748         /*
1749          * If we are requested for another RTE then we have to suspend
1750          * execution of current PlanQual and start execution for new one.
1751          */
1752         if (epq == NULL || epq->rti != rti)
1753         {
1754                 /* try to reuse plan used previously */
1755                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1756
1757                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1758                 {
1759                         newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1760                         newepq->free = NULL;
1761
1762                         /*
1763                          * Each stack level has its own copy of the plan tree.  This
1764                          * is wasteful, but necessary as long as plan nodes point to
1765                          * exec state nodes rather than vice versa.  Note that
1766                          * copyfuncs.c doesn't attempt to copy the exec state nodes,
1767                          * which is a good thing in this situation.
1768                          */
1769                         newepq->plan = copyObject(estate->es_origPlan);
1770
1771                         /*
1772                          * Init stack level's EState.  We share top level's copy of
1773                          * es_result_relations array and other non-changing status. We
1774                          * need our own tupletable, es_param_exec_vals, and other
1775                          * changeable state.
1776                          */
1777                         epqstate = &(newepq->estate);
1778                         memcpy(epqstate, estate, sizeof(EState));
1779                         epqstate->es_direction = ForwardScanDirection;
1780                         if (estate->es_origPlan->nParamExec > 0)
1781                                 epqstate->es_param_exec_vals = (ParamExecData *)
1782                                         palloc(estate->es_origPlan->nParamExec *
1783                                                    sizeof(ParamExecData));
1784                         epqstate->es_tupleTable = NULL;
1785                         epqstate->es_per_tuple_exprcontext = NULL;
1786
1787                         /*
1788                          * Each epqstate must have its own es_evTupleNull state, but
1789                          * all the stack entries share es_evTuple state.  This allows
1790                          * sub-rechecks to inherit the value being examined by an
1791                          * outer recheck.
1792                          */
1793                         epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1794                         if (epq == NULL)
1795                         {
1796                                 /* first PQ stack entry */
1797                                 epqstate->es_evTuple = (HeapTuple *)
1798                                         palloc(rtsize * sizeof(HeapTuple));
1799                                 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1800                         }
1801                         else
1802                         {
1803                                 /* later stack entries share the same storage */
1804                                 epqstate->es_evTuple = epq->estate.es_evTuple;
1805                         }
1806                 }
1807                 else
1808                 {
1809                         /* recycle previously used EState */
1810                         epqstate = &(newepq->estate);
1811                 }
1812                 /* push current PQ to the stack */
1813                 epqstate->es_evalPlanQual = (Pointer) epq;
1814                 epq = newepq;
1815                 estate->es_evalPlanQual = (Pointer) epq;
1816                 epq->rti = rti;
1817                 endNode = false;
1818         }
1819
1820         Assert(epq->rti == rti);
1821         epqstate = &(epq->estate);
1822
1823         /*
1824          * Ok - we're requested for the same RTE.  Unfortunately we still have
1825          * to end and restart execution of the plan, because ExecReScan
1826          * wouldn't ensure that upper plan nodes would reset themselves.  We
1827          * could make that work if insertion of the target tuple were
1828          * integrated with the Param mechanism somehow, so that the upper plan
1829          * nodes know that their children's outputs have changed.
1830          */
1831         if (endNode)
1832         {
1833                 /* stop execution */
1834                 ExecEndNode(epq->plan, NULL);
1835                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1836                 epqstate->es_tupleTable = NULL;
1837         }
1838
1839         /*
1840          * free old RTE' tuple, if any, and store target tuple where
1841          * relation's scan node will see it
1842          */
1843         if (epqstate->es_evTuple[rti - 1] != NULL)
1844                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1845         epqstate->es_evTuple[rti - 1] = copyTuple;
1846
1847         /*
1848          * Initialize for new recheck query; be careful to copy down state
1849          * that might have changed in top EState.
1850          */
1851         epqstate->es_result_relation_info = estate->es_result_relation_info;
1852         epqstate->es_junkFilter = estate->es_junkFilter;
1853         if (estate->es_origPlan->nParamExec > 0)
1854                 memset(epqstate->es_param_exec_vals, 0,
1855                            estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1856         memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1857         epqstate->es_useEvalPlan = false;
1858         Assert(epqstate->es_tupleTable == NULL);
1859         epqstate->es_tupleTable =
1860                 ExecCreateTupleTable(estate->es_tupleTable->size);
1861
1862         ExecInitNode(epq->plan, epqstate, NULL);
1863
1864         return EvalPlanQualNext(estate);
1865 }
1866
1867 static TupleTableSlot *
1868 EvalPlanQualNext(EState *estate)
1869 {
1870         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1871         EState     *epqstate = &(epq->estate);
1872         evalPlanQual *oldepq;
1873         TupleTableSlot *slot;
1874
1875         Assert(epq->rti != 0);
1876
1877 lpqnext:;
1878         slot = ExecProcNode(epq->plan, NULL);
1879
1880         /*
1881          * No more tuples for this PQ. Continue previous one.
1882          */
1883         if (TupIsNull(slot))
1884         {
1885                 /* stop execution */
1886                 ExecEndNode(epq->plan, NULL);
1887                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1888                 epqstate->es_tupleTable = NULL;
1889                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1890                 epqstate->es_evTuple[epq->rti - 1] = NULL;
1891                 /* pop old PQ from the stack */
1892                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1893                 if (oldepq == (evalPlanQual *) NULL)
1894                 {
1895                         epq->rti = 0;           /* this is the first (oldest) */
1896                         estate->es_useEvalPlan = false;         /* PQ - mark as free and          */
1897                         return (NULL);          /* continue Query execution   */
1898                 }
1899                 Assert(oldepq->rti != 0);
1900                 /* push current PQ to freePQ stack */
1901                 oldepq->free = epq;
1902                 epq = oldepq;
1903                 epqstate = &(epq->estate);
1904                 estate->es_evalPlanQual = (Pointer) epq;
1905                 goto lpqnext;
1906         }
1907
1908         return (slot);
1909 }
1910
1911 static void
1912 EndEvalPlanQual(EState *estate)
1913 {
1914         evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1915         EState     *epqstate = &(epq->estate);
1916         evalPlanQual *oldepq;
1917
1918         if (epq->rti == 0)                      /* plans already shutdowned */
1919         {
1920                 Assert(epq->estate.es_evalPlanQual == NULL);
1921                 return;
1922         }
1923
1924         for (;;)
1925         {
1926                 /* stop execution */
1927                 ExecEndNode(epq->plan, NULL);
1928                 ExecDropTupleTable(epqstate->es_tupleTable, true);
1929                 epqstate->es_tupleTable = NULL;
1930                 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1931                 {
1932                         heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1933                         epqstate->es_evTuple[epq->rti - 1] = NULL;
1934                 }
1935                 /* pop old PQ from the stack */
1936                 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1937                 if (oldepq == (evalPlanQual *) NULL)
1938                 {
1939                         epq->rti = 0;           /* this is the first (oldest) */
1940                         estate->es_useEvalPlan = false;         /* PQ - mark as free */
1941                         break;
1942                 }
1943                 Assert(oldepq->rti != 0);
1944                 /* push current PQ to freePQ stack */
1945                 oldepq->free = epq;
1946                 epq = oldepq;
1947                 epqstate = &(epq->estate);
1948                 estate->es_evalPlanQual = (Pointer) epq;
1949         }
1950 }