granicus.if.org Git - postgresql/blob - src/backend/executor/execMain.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * execMain.c
   4  *        top level executor interface routines
   5  *
   6  * INTERFACE ROUTINES
   7  *      ExecutorStart()
   8  *      ExecutorRun()
   9  *      ExecutorEnd()
  10  *
  11  *      The old ExecutorMain() has been replaced by ExecutorStart(),
  12  *      ExecutorRun() and ExecutorEnd()
  13  *
  14  *      These three procedures are the external interfaces to the executor.
  15  *      In each case, the query descriptor is required as an argument.
  16  *
  17  *      ExecutorStart() must be called at the beginning of execution of any
  18  *      query plan and ExecutorEnd() should always be called at the end of
  19  *      execution of a plan.
  20  *
  21  *      ExecutorRun accepts direction and count arguments that specify whether
  22  *      the plan is to be executed forwards, backwards, and for how many tuples.
  23  *
  24  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  25  * Portions Copyright (c) 1994, Regents of the University of California
  26  *
  27  *
  28  * IDENTIFICATION
  29  *        $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.200 2003/02/03 15:07:06 tgl Exp $
  30  *
  31  *-------------------------------------------------------------------------
  32  */
  33 #include "postgres.h"
  34
  35 #include "access/heapam.h"
  36 #include "catalog/heap.h"
  37 #include "catalog/namespace.h"
  38 #include "commands/tablecmds.h"
  39 #include "commands/trigger.h"
  40 #include "executor/execdebug.h"
  41 #include "executor/execdefs.h"
  42 #include "miscadmin.h"
  43 #include "optimizer/var.h"
  44 #include "parser/parsetree.h"
  45 #include "utils/acl.h"
  46 #include "utils/lsyscache.h"
  47
  48
  49 typedef struct execRowMark
  50 {
  51         Relation        relation;
  52         Index           rti;
  53         char            resname[32];
  54 } execRowMark;
  55
  56 typedef struct evalPlanQual
  57 {
  58         Index           rti;
  59         EState     *estate;
  60         PlanState  *planstate;
  61         struct evalPlanQual *next;      /* stack of active PlanQual plans */
  62         struct evalPlanQual *free;      /* list of free PlanQual plans */
  63 } evalPlanQual;
  64
  65 /* decls for local routines only used within this module */
  66 static void InitPlan(QueryDesc *queryDesc);
  67 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
  68                                   Index resultRelationIndex,
  69                                   List *rangeTable,
  70                                   CmdType operation);
  71 static TupleTableSlot *ExecutePlan(EState *estate, PlanState *planstate,
  72                         CmdType operation,
  73                         long numberTuples,
  74                         ScanDirection direction,
  75                         DestReceiver *destfunc);
  76 static void ExecSelect(TupleTableSlot *slot,
  77                    DestReceiver *destfunc,
  78                    EState *estate);
  79 static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid,
  80                    EState *estate);
  81 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
  82                    EState *estate);
  83 static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid,
  84                    EState *estate);
  85 static TupleTableSlot *EvalPlanQualNext(EState *estate);
  86 static void EndEvalPlanQual(EState *estate);
  87 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
  88 static void ExecCheckXactReadOnly(Query *parsetree, CmdType operation);
  89 static void EvalPlanQualStart(evalPlanQual *epq, EState *estate,
  90                                                           evalPlanQual *priorepq);
  91 static void EvalPlanQualStop(evalPlanQual *epq);
  92
  93 /* end of local decls */
  94
  95
  96 /* ----------------------------------------------------------------
  97  *              ExecutorStart
  98  *
  99  *              This routine must be called at the beginning of any execution of any
 100  *              query plan
 101  *
 102  * Takes a QueryDesc previously created by CreateQueryDesc (it's not real
 103  * clear why we bother to separate the two functions, but...).  The tupDesc
 104  * field of the QueryDesc is filled in to describe the tuples that will be
 105  * returned, and the internal fields (estate and planstate) are set up.
 106  *
 107  * NB: the CurrentMemoryContext when this is called will become the parent
 108  * of the per-query context used for this Executor invocation.
 109  * ----------------------------------------------------------------
 110  */
 111 void
 112 ExecutorStart(QueryDesc *queryDesc)
 113 {
 114         EState     *estate;
 115         MemoryContext oldcontext;
 116
 117         /* sanity checks: queryDesc must not be started already */
 118         Assert(queryDesc != NULL);
 119         Assert(queryDesc->estate == NULL);
 120
 121         /*
 122          * Build EState, switch into per-query memory context for startup.
 123          */
 124         estate = CreateExecutorState();
 125         queryDesc->estate = estate;
 126
 127         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 128
 129         /*
 130          * Fill in parameters, if any, from queryDesc
 131          */
 132         estate->es_param_list_info = queryDesc->params;
 133
 134         if (queryDesc->plantree->nParamExec > 0)
 135                 estate->es_param_exec_vals = (ParamExecData *)
 136                         palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
 137
 138         estate->es_instrument = queryDesc->doInstrument;
 139
 140         /*
 141          * Make our own private copy of the current query snapshot data.
 142          *
 143          * This "freezes" our idea of which tuples are good and which are not for
 144          * the life of this query, even if it outlives the current command and
 145          * current snapshot.
 146          */
 147         estate->es_snapshot = CopyQuerySnapshot();
 148
 149         /*
 150          * Initialize the plan state tree
 151          */
 152         InitPlan(queryDesc);
 153
 154         MemoryContextSwitchTo(oldcontext);
 155 }
 156
 157 /* ----------------------------------------------------------------
 158  *              ExecutorRun
 159  *
 160  *              This is the main routine of the executor module. It accepts
 161  *              the query descriptor from the traffic cop and executes the
 162  *              query plan.
 163  *
 164  *              ExecutorStart must have been called already.
 165  *
 166  *              If direction is NoMovementScanDirection then nothing is done
 167  *              except to start up/shut down the destination.  Otherwise,
 168  *              we retrieve up to 'count' tuples in the specified direction.
 169  *
 170  *              Note: count = 0 is interpreted as no portal limit, i.e., run to
 171  *              completion.
 172  *
 173  * ----------------------------------------------------------------
 174  */
 175 TupleTableSlot *
 176 ExecutorRun(QueryDesc *queryDesc,
 177                         ScanDirection direction, long count)
 178 {
 179         EState     *estate;
 180         CmdType         operation;
 181         CommandDest dest;
 182         DestReceiver *destfunc;
 183         TupleTableSlot *result;
 184         MemoryContext oldcontext;
 185
 186         /* sanity checks */
 187         Assert(queryDesc != NULL);
 188
 189         estate = queryDesc->estate;
 190
 191         Assert(estate != NULL);
 192
 193         /*
 194          * Switch into per-query memory context
 195          */
 196         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 197
 198         /*
 199          * extract information from the query descriptor and the query
 200          * feature.
 201          */
 202         operation = queryDesc->operation;
 203         dest = queryDesc->dest;
 204
 205         /*
 206          * If the transaction is read-only, we need to check if any writes
 207          * are planned to non-temporary tables.  This is done here at this
 208          * rather late stage so that we can handle EXPLAIN vs. EXPLAIN
 209          * ANALYZE easily.
 210          */
 211         ExecCheckXactReadOnly(queryDesc->parsetree, operation);
 212
 213         /*
 214          * startup tuple receiver
 215          */
 216         estate->es_processed = 0;
 217         estate->es_lastoid = InvalidOid;
 218
 219         destfunc = DestToFunction(dest);
 220         (*destfunc->setup) (destfunc, (int) operation,
 221                                                 queryDesc->portalName, queryDesc->tupDesc);
 222
 223         /*
 224          * run plan
 225          */
 226         if (direction == NoMovementScanDirection)
 227                 result = NULL;
 228         else
 229                 result = ExecutePlan(estate,
 230                                                          queryDesc->planstate,
 231                                                          operation,
 232                                                          count,
 233                                                          direction,
 234                                                          destfunc);
 235
 236         /*
 237          * shutdown receiver
 238          */
 239         (*destfunc->cleanup) (destfunc);
 240
 241         MemoryContextSwitchTo(oldcontext);
 242
 243         return result;
 244 }
 245
 246 /* ----------------------------------------------------------------
 247  *              ExecutorEnd
 248  *
 249  *              This routine must be called at the end of execution of any
 250  *              query plan
 251  * ----------------------------------------------------------------
 252  */
 253 void
 254 ExecutorEnd(QueryDesc *queryDesc)
 255 {
 256         EState     *estate;
 257         MemoryContext oldcontext;
 258
 259         /* sanity checks */
 260         Assert(queryDesc != NULL);
 261
 262         estate = queryDesc->estate;
 263
 264         Assert(estate != NULL);
 265
 266         /*
 267          * Switch into per-query memory context to run ExecEndPlan
 268          */
 269         oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
 270
 271         ExecEndPlan(queryDesc->planstate, estate);
 272
 273         /*
 274          * Must switch out of context before destroying it
 275          */
 276         MemoryContextSwitchTo(oldcontext);
 277
 278         /*
 279          * Release EState and per-query memory context.  This should release
 280          * everything the executor has allocated.
 281          */
 282         FreeExecutorState(estate);
 283
 284         /* Reset queryDesc fields that no longer point to anything */
 285         queryDesc->tupDesc = NULL;
 286         queryDesc->estate = NULL;
 287         queryDesc->planstate = NULL;
 288 }
 289
 290
 291 /*
 292  * ExecCheckRTPerms
 293  *              Check access permissions for all relations listed in a range table.
 294  */
 295 void
 296 ExecCheckRTPerms(List *rangeTable, CmdType operation)
 297 {
 298         List       *lp;
 299
 300         foreach(lp, rangeTable)
 301         {
 302                 RangeTblEntry *rte = lfirst(lp);
 303
 304                 ExecCheckRTEPerms(rte, operation);
 305         }
 306 }
 307
 308 /*
 309  * ExecCheckRTEPerms
 310  *              Check access permissions for a single RTE.
 311  */
 312 static void
 313 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
 314 {
 315         Oid                     relOid;
 316         AclId           userid;
 317         AclResult       aclcheck_result;
 318
 319         /*
 320          * If it's a subquery, recursively examine its rangetable.
 321          */
 322         if (rte->rtekind == RTE_SUBQUERY)
 323         {
 324                 ExecCheckRTPerms(rte->subquery->rtable, operation);
 325                 return;
 326         }
 327
 328         /*
 329          * Otherwise, only plain-relation RTEs need to be checked here.
 330          * Function RTEs are checked by init_fcache when the function is prepared
 331          * for execution. Join and special RTEs need no checks.
 332          */
 333         if (rte->rtekind != RTE_RELATION)
 334                 return;
 335
 336         relOid = rte->relid;
 337
 338         /*
 339          * userid to check as: current user unless we have a setuid
 340          * indication.
 341          *
 342          * Note: GetUserId() is presently fast enough that there's no harm in
 343          * calling it separately for each RTE.  If that stops being true, we
 344          * could call it once in ExecCheckRTPerms and pass the userid down
 345          * from there.  But for now, no need for the extra clutter.
 346          */
 347         userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 348
 349 #define CHECK(MODE)             pg_class_aclcheck(relOid, userid, MODE)
 350
 351         if (rte->checkForRead)
 352         {
 353                 aclcheck_result = CHECK(ACL_SELECT);
 354                 if (aclcheck_result != ACLCHECK_OK)
 355                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 356         }
 357
 358         if (rte->checkForWrite)
 359         {
 360                 /*
 361                  * Note: write access in a SELECT context means SELECT FOR UPDATE.
 362                  * Right now we don't distinguish that from true update as far as
 363                  * permissions checks are concerned.
 364                  */
 365                 switch (operation)
 366                 {
 367                         case CMD_INSERT:
 368                                 aclcheck_result = CHECK(ACL_INSERT);
 369                                 break;
 370                         case CMD_SELECT:
 371                         case CMD_UPDATE:
 372                                 aclcheck_result = CHECK(ACL_UPDATE);
 373                                 break;
 374                         case CMD_DELETE:
 375                                 aclcheck_result = CHECK(ACL_DELETE);
 376                                 break;
 377                         default:
 378                                 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
 379                                          operation);
 380                                 aclcheck_result = ACLCHECK_OK;  /* keep compiler quiet */
 381                                 break;
 382                 }
 383                 if (aclcheck_result != ACLCHECK_OK)
 384                         aclcheck_error(aclcheck_result, get_rel_name(relOid));
 385         }
 386 }
 387
 388
 389 /* ===============================================================
 390  * ===============================================================
 391                                                  static routines follow
 392  * ===============================================================
 393  * ===============================================================
 394  */
 395
 396
 397 static void
 398 ExecCheckXactReadOnly(Query *parsetree, CmdType operation)
 399 {
 400         if (!XactReadOnly)
 401                 return;
 402
 403         /* CREATE TABLE AS or SELECT INTO */
 404         if (operation == CMD_SELECT && parsetree->into != NULL)
 405                 goto fail;
 406
 407         if (operation == CMD_DELETE || operation == CMD_INSERT
 408                 || operation == CMD_UPDATE)
 409         {
 410                 List *lp;
 411
 412                 foreach(lp, parsetree->rtable)
 413                 {
 414                         RangeTblEntry *rte = lfirst(lp);
 415
 416                         if (rte->rtekind != RTE_RELATION)
 417                                 continue;
 418
 419                         if (!rte->checkForWrite)
 420                                 continue;
 421
 422                         if (isTempNamespace(get_rel_namespace(rte->relid)))
 423                                 continue;
 424
 425                         goto fail;
 426                 }
 427         }
 428
 429         return;
 430
 431 fail:
 432         elog(ERROR, "transaction is read-only");
 433 }
 434
 435
 436 /* ----------------------------------------------------------------
 437  *              InitPlan
 438  *
 439  *              Initializes the query plan: open files, allocate storage
 440  *              and start up the rule manager
 441  * ----------------------------------------------------------------
 442  */
 443 static void
 444 InitPlan(QueryDesc *queryDesc)
 445 {
 446         CmdType         operation = queryDesc->operation;
 447         Query *parseTree = queryDesc->parsetree;
 448         Plan *plan = queryDesc->plantree;
 449         EState *estate = queryDesc->estate;
 450         PlanState  *planstate;
 451         List       *rangeTable;
 452         Relation        intoRelationDesc;
 453         bool            do_select_into;
 454         TupleDesc       tupType;
 455
 456         /*
 457          * Do permissions checks.  It's sufficient to examine the query's
 458          * top rangetable here --- subplan RTEs will be checked during
 459          * ExecInitSubPlan().
 460          */
 461         ExecCheckRTPerms(parseTree->rtable, operation);
 462
 463         /*
 464          * get information from query descriptor
 465          */
 466         rangeTable = parseTree->rtable;
 467
 468         /*
 469          * initialize the node's execution state
 470          */
 471         estate->es_range_table = rangeTable;
 472
 473         /*
 474          * if there is a result relation, initialize result relation stuff
 475          */
 476         if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
 477         {
 478                 List       *resultRelations = parseTree->resultRelations;
 479                 int                     numResultRelations;
 480                 ResultRelInfo *resultRelInfos;
 481
 482                 if (resultRelations != NIL)
 483                 {
 484                         /*
 485                          * Multiple result relations (due to inheritance)
 486                          * parseTree->resultRelations identifies them all
 487                          */
 488                         ResultRelInfo *resultRelInfo;
 489
 490                         numResultRelations = length(resultRelations);
 491                         resultRelInfos = (ResultRelInfo *)
 492                                 palloc(numResultRelations * sizeof(ResultRelInfo));
 493                         resultRelInfo = resultRelInfos;
 494                         while (resultRelations != NIL)
 495                         {
 496                                 initResultRelInfo(resultRelInfo,
 497                                                                   lfirsti(resultRelations),
 498                                                                   rangeTable,
 499                                                                   operation);
 500                                 resultRelInfo++;
 501                                 resultRelations = lnext(resultRelations);
 502                         }
 503                 }
 504                 else
 505                 {
 506                         /*
 507                          * Single result relation identified by
 508                          * parseTree->resultRelation
 509                          */
 510                         numResultRelations = 1;
 511                         resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
 512                         initResultRelInfo(resultRelInfos,
 513                                                           parseTree->resultRelation,
 514                                                           rangeTable,
 515                                                           operation);
 516                 }
 517
 518                 estate->es_result_relations = resultRelInfos;
 519                 estate->es_num_result_relations = numResultRelations;
 520                 /* Initialize to first or only result rel */
 521                 estate->es_result_relation_info = resultRelInfos;
 522         }
 523         else
 524         {
 525                 /*
 526                  * if no result relation, then set state appropriately
 527                  */
 528                 estate->es_result_relations = NULL;
 529                 estate->es_num_result_relations = 0;
 530                 estate->es_result_relation_info = NULL;
 531         }
 532
 533         /*
 534          * Detect whether we're doing SELECT INTO.  If so, set the force_oids
 535          * flag appropriately so that the plan tree will be initialized with
 536          * the correct tuple descriptors.
 537          */
 538         do_select_into = false;
 539
 540         if (operation == CMD_SELECT &&
 541                 !parseTree->isPortal &&
 542                 parseTree->into != NULL)
 543         {
 544                 do_select_into = true;
 545                 /*
 546                  * For now, always create OIDs in SELECT INTO; this is for backwards
 547                  * compatibility with pre-7.3 behavior.  Eventually we might want
 548                  * to allow the user to choose.
 549                  */
 550                 estate->es_force_oids = true;
 551         }
 552
 553         /*
 554          * Have to lock relations selected for update
 555          */
 556         estate->es_rowMark = NIL;
 557         if (parseTree->rowMarks != NIL)
 558         {
 559                 List       *l;
 560
 561                 foreach(l, parseTree->rowMarks)
 562                 {
 563                         Index           rti = lfirsti(l);
 564                         Oid                     relid = getrelid(rti, rangeTable);
 565                         Relation        relation;
 566                         execRowMark *erm;
 567
 568                         relation = heap_open(relid, RowShareLock);
 569                         erm = (execRowMark *) palloc(sizeof(execRowMark));
 570                         erm->relation = relation;
 571                         erm->rti = rti;
 572                         snprintf(erm->resname, 32, "ctid%u", rti);
 573                         estate->es_rowMark = lappend(estate->es_rowMark, erm);
 574                 }
 575         }
 576
 577         /*
 578          * initialize the executor "tuple" table.  We need slots for all the
 579          * plan nodes, plus possibly output slots for the junkfilter(s). At
 580          * this point we aren't sure if we need junkfilters, so just add slots
 581          * for them unconditionally.
 582          */
 583         {
 584                 int                     nSlots = ExecCountSlotsNode(plan);
 585
 586                 if (parseTree->resultRelations != NIL)
 587                         nSlots += length(parseTree->resultRelations);
 588                 else
 589                         nSlots += 1;
 590                 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 591         }
 592
 593         /* mark EvalPlanQual not active */
 594         estate->es_topPlan = plan;
 595         estate->es_evalPlanQual = NULL;
 596         estate->es_evTupleNull = NULL;
 597         estate->es_evTuple = NULL;
 598         estate->es_useEvalPlan = false;
 599
 600         /*
 601          * initialize the private state information for all the nodes in the
 602          * query tree.  This opens files, allocates storage and leaves us
 603          * ready to start processing tuples.
 604          */
 605         planstate = ExecInitNode(plan, estate);
 606
 607         /*
 608          * Get the tuple descriptor describing the type of tuples to return.
 609          * (this is especially important if we are creating a relation with
 610          * "SELECT INTO")
 611          */
 612         tupType = ExecGetTupType(planstate);
 613
 614         /*
 615          * Initialize the junk filter if needed.  SELECT and INSERT queries need a
 616          * filter if there are any junk attrs in the tlist.  INSERT and SELECT
 617          * INTO also need a filter if the top plan node is a scan node that's not
 618          * doing projection (else we'll be scribbling on the scan tuple!)  UPDATE
 619          * and DELETE always need a filter, since there's always a junk 'ctid'
 620          * attribute present --- no need to look first.
 621          */
 622         {
 623                 bool            junk_filter_needed = false;
 624                 List       *tlist;
 625
 626                 switch (operation)
 627                 {
 628                         case CMD_SELECT:
 629                         case CMD_INSERT:
 630                                 foreach(tlist, plan->targetlist)
 631                                 {
 632                                         TargetEntry *tle = (TargetEntry *) lfirst(tlist);
 633
 634                                         if (tle->resdom->resjunk)
 635                                         {
 636                                                 junk_filter_needed = true;
 637                                                 break;
 638                                         }
 639                                 }
 640                                 if (!junk_filter_needed &&
 641                                         (operation == CMD_INSERT || do_select_into))
 642                                 {
 643                                         if (IsA(planstate, SeqScanState) ||
 644                                                 IsA(planstate, IndexScanState) ||
 645                                                 IsA(planstate, TidScanState) ||
 646                                                 IsA(planstate, SubqueryScanState) ||
 647                                                 IsA(planstate, FunctionScanState))
 648                                         {
 649                                                 if (planstate->ps_ProjInfo == NULL)
 650                                                         junk_filter_needed = true;
 651                                         }
 652                                 }
 653                                 break;
 654                         case CMD_UPDATE:
 655                         case CMD_DELETE:
 656                                 junk_filter_needed = true;
 657                                 break;
 658                         default:
 659                                 break;
 660                 }
 661
 662                 if (junk_filter_needed)
 663                 {
 664                         /*
 665                          * If there are multiple result relations, each one needs its
 666                          * own junk filter.  Note this is only possible for
 667                          * UPDATE/DELETE, so we can't be fooled by some needing a
 668                          * filter and some not.
 669                          */
 670                         if (parseTree->resultRelations != NIL)
 671                         {
 672                                 PlanState **appendplans;
 673                                 int                     as_nplans;
 674                                 ResultRelInfo *resultRelInfo;
 675                                 int                     i;
 676
 677                                 /* Top plan had better be an Append here. */
 678                                 Assert(IsA(plan, Append));
 679                                 Assert(((Append *) plan)->isTarget);
 680                                 Assert(IsA(planstate, AppendState));
 681                                 appendplans = ((AppendState *) planstate)->appendplans;
 682                                 as_nplans = ((AppendState *) planstate)->as_nplans;
 683                                 Assert(as_nplans == estate->es_num_result_relations);
 684                                 resultRelInfo = estate->es_result_relations;
 685                                 for (i = 0; i < as_nplans; i++)
 686                                 {
 687                                         PlanState  *subplan = appendplans[i];
 688                                         JunkFilter *j;
 689
 690                                         j = ExecInitJunkFilter(subplan->plan->targetlist,
 691                                                                                    ExecGetTupType(subplan),
 692                                                           ExecAllocTableSlot(estate->es_tupleTable));
 693                                         resultRelInfo->ri_junkFilter = j;
 694                                         resultRelInfo++;
 695                                 }
 696
 697                                 /*
 698                                  * Set active junkfilter too; at this point ExecInitAppend
 699                                  * has already selected an active result relation...
 700                                  */
 701                                 estate->es_junkFilter =
 702                                         estate->es_result_relation_info->ri_junkFilter;
 703                         }
 704                         else
 705                         {
 706                                 /* Normal case with just one JunkFilter */
 707                                 JunkFilter *j;
 708
 709                                 j = ExecInitJunkFilter(planstate->plan->targetlist,
 710                                                                            tupType,
 711                                                           ExecAllocTableSlot(estate->es_tupleTable));
 712                                 estate->es_junkFilter = j;
 713                                 if (estate->es_result_relation_info)
 714                                         estate->es_result_relation_info->ri_junkFilter = j;
 715
 716                                 /* For SELECT, want to return the cleaned tuple type */
 717                                 if (operation == CMD_SELECT)
 718                                         tupType = j->jf_cleanTupType;
 719                         }
 720                 }
 721                 else
 722                         estate->es_junkFilter = NULL;
 723         }
 724
 725         /*
 726          * If doing SELECT INTO, initialize the "into" relation.  We must wait
 727          * till now so we have the "clean" result tuple type to create the
 728          * new table from.
 729          */
 730         intoRelationDesc = (Relation) NULL;
 731
 732         if (do_select_into)
 733         {
 734                 char       *intoName;
 735                 Oid                     namespaceId;
 736                 AclResult       aclresult;
 737                 Oid                     intoRelationId;
 738                 TupleDesc       tupdesc;
 739
 740                 /*
 741                  * find namespace to create in, check permissions
 742                  */
 743                 intoName = parseTree->into->relname;
 744                 namespaceId = RangeVarGetCreationNamespace(parseTree->into);
 745
 746                 aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
 747                                                                                   ACL_CREATE);
 748                 if (aclresult != ACLCHECK_OK)
 749                         aclcheck_error(aclresult, get_namespace_name(namespaceId));
 750
 751                 /*
 752                  * have to copy tupType to get rid of constraints
 753                  */
 754                 tupdesc = CreateTupleDescCopy(tupType);
 755
 756                 intoRelationId = heap_create_with_catalog(intoName,
 757                                                                                                   namespaceId,
 758                                                                                                   tupdesc,
 759                                                                                                   RELKIND_RELATION,
 760                                                                                                   false,
 761                                                                                                   ONCOMMIT_NOOP,
 762                                                                                                   allowSystemTableMods);
 763
 764                 FreeTupleDesc(tupdesc);
 765
 766                 /*
 767                  * Advance command counter so that the newly-created
 768                  * relation's catalog tuples will be visible to heap_open.
 769                  */
 770                 CommandCounterIncrement();
 771
 772                 /*
 773                  * If necessary, create a TOAST table for the into
 774                  * relation. Note that AlterTableCreateToastTable ends
 775                  * with CommandCounterIncrement(), so that the TOAST table
 776                  * will be visible for insertion.
 777                  */
 778                 AlterTableCreateToastTable(intoRelationId, true);
 779
 780                 /*
 781                  * And open the constructed table for writing.
 782                  */
 783                 intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock);
 784         }
 785
 786         estate->es_into_relation_descriptor = intoRelationDesc;
 787
 788         queryDesc->tupDesc = tupType;
 789         queryDesc->planstate = planstate;
 790 }
 791
 792 /*
 793  * Initialize ResultRelInfo data for one result relation
 794  */
 795 static void
 796 initResultRelInfo(ResultRelInfo *resultRelInfo,
 797                                   Index resultRelationIndex,
 798                                   List *rangeTable,
 799                                   CmdType operation)
 800 {
 801         Oid                     resultRelationOid;
 802         Relation        resultRelationDesc;
 803
 804         resultRelationOid = getrelid(resultRelationIndex, rangeTable);
 805         resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
 806
 807         switch (resultRelationDesc->rd_rel->relkind)
 808         {
 809                 case RELKIND_SEQUENCE:
 810                         elog(ERROR, "You can't change sequence relation %s",
 811                                  RelationGetRelationName(resultRelationDesc));
 812                         break;
 813                 case RELKIND_TOASTVALUE:
 814                         elog(ERROR, "You can't change toast relation %s",
 815                                  RelationGetRelationName(resultRelationDesc));
 816                         break;
 817                 case RELKIND_VIEW:
 818                         elog(ERROR, "You can't change view relation %s",
 819                                  RelationGetRelationName(resultRelationDesc));
 820                         break;
 821         }
 822
 823         MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
 824         resultRelInfo->type = T_ResultRelInfo;
 825         resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
 826         resultRelInfo->ri_RelationDesc = resultRelationDesc;
 827         resultRelInfo->ri_NumIndices = 0;
 828         resultRelInfo->ri_IndexRelationDescs = NULL;
 829         resultRelInfo->ri_IndexRelationInfo = NULL;
 830         /* make a copy so as not to depend on relcache info not changing... */
 831         resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
 832         resultRelInfo->ri_TrigFunctions = NULL;
 833         resultRelInfo->ri_ConstraintExprs = NULL;
 834         resultRelInfo->ri_junkFilter = NULL;
 835
 836         /*
 837          * If there are indices on the result relation, open them and save
 838          * descriptors in the result relation info, so that we can add new
 839          * index entries for the tuples we add/update.  We need not do this
 840          * for a DELETE, however, since deletion doesn't affect indexes.
 841          */
 842         if (resultRelationDesc->rd_rel->relhasindex &&
 843                 operation != CMD_DELETE)
 844                 ExecOpenIndices(resultRelInfo);
 845 }
 846
 847 /* ----------------------------------------------------------------
 848  *              ExecEndPlan
 849  *
 850  *              Cleans up the query plan -- closes files and frees up storage
 851  *
 852  * NOTE: we are no longer very worried about freeing storage per se
 853  * in this code; FreeExecutorState should be guaranteed to release all
 854  * memory that needs to be released.  What we are worried about doing
 855  * is closing relations and dropping buffer pins.  Thus, for example,
 856  * tuple tables must be cleared or dropped to ensure pins are released.
 857  * ----------------------------------------------------------------
 858  */
 859 void
 860 ExecEndPlan(PlanState *planstate, EState *estate)
 861 {
 862         ResultRelInfo *resultRelInfo;
 863         int                     i;
 864         List       *l;
 865
 866         /*
 867          * shut down any PlanQual processing we were doing
 868          */
 869         if (estate->es_evalPlanQual != NULL)
 870                 EndEvalPlanQual(estate);
 871
 872         /*
 873          * shut down the node-type-specific query processing
 874          */
 875         ExecEndNode(planstate);
 876
 877         /*
 878          * destroy the executor "tuple" table.
 879          */
 880         ExecDropTupleTable(estate->es_tupleTable, true);
 881         estate->es_tupleTable = NULL;
 882
 883         /*
 884          * close the result relation(s) if any, but hold locks until xact
 885          * commit.
 886          */
 887         resultRelInfo = estate->es_result_relations;
 888         for (i = estate->es_num_result_relations; i > 0; i--)
 889         {
 890                 /* Close indices and then the relation itself */
 891                 ExecCloseIndices(resultRelInfo);
 892                 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 893                 resultRelInfo++;
 894         }
 895
 896         /*
 897          * close the "into" relation if necessary, again keeping lock
 898          */
 899         if (estate->es_into_relation_descriptor != NULL)
 900                 heap_close(estate->es_into_relation_descriptor, NoLock);
 901
 902         /*
 903          * close any relations selected FOR UPDATE, again keeping locks
 904          */
 905         foreach(l, estate->es_rowMark)
 906         {
 907                 execRowMark *erm = lfirst(l);
 908
 909                 heap_close(erm->relation, NoLock);
 910         }
 911 }
 912
 913 /* ----------------------------------------------------------------
 914  *              ExecutePlan
 915  *
 916  *              processes the query plan to retrieve 'numberTuples' tuples in the
 917  *              direction specified.
 918  *
 919  *              Retrieves all tuples if numberTuples is 0
 920  *
 921  *              result is either a slot containing the last tuple in the case
 922  *              of a SELECT or NULL otherwise.
 923  *
 924  * Note: the ctid attribute is a 'junk' attribute that is removed before the
 925  * user can see it
 926  * ----------------------------------------------------------------
 927  */
 928 static TupleTableSlot *
 929 ExecutePlan(EState *estate,
 930                         PlanState *planstate,
 931                         CmdType operation,
 932                         long numberTuples,
 933                         ScanDirection direction,
 934                         DestReceiver *destfunc)
 935 {
 936         JunkFilter                      *junkfilter;
 937         TupleTableSlot          *slot;
 938         ItemPointer                      tupleid = NULL;
 939         ItemPointerData          tuple_ctid;
 940         long                             current_tuple_count;
 941         TupleTableSlot          *result;
 942
 943         /*
 944          * initialize local variables
 945          */
 946         slot = NULL;
 947         current_tuple_count = 0;
 948         result = NULL;
 949
 950         /*
 951          * Set the direction.
 952          */
 953         estate->es_direction = direction;
 954
 955         /*
 956          * Process BEFORE EACH STATEMENT triggers
 957          */
 958         switch (operation)
 959         {
 960                 case CMD_UPDATE:
 961                         ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
 962                         break;
 963                 case CMD_DELETE:
 964                         ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
 965                         break;
 966                 case CMD_INSERT:
 967                         ExecBSInsertTriggers(estate, estate->es_result_relation_info);
 968                         break;
 969                 default:
 970                         /* do nothing */
 971                         break;
 972         }
 973
 974         /*
 975          * Loop until we've processed the proper number of tuples from the
 976          * plan.
 977          */
 978
 979         for (;;)
 980         {
 981                 /* Reset the per-output-tuple exprcontext */
 982                 ResetPerTupleExprContext(estate);
 983
 984                 /*
 985                  * Execute the plan and obtain a tuple
 986                  */
 987 lnext:  ;
 988                 if (estate->es_useEvalPlan)
 989                 {
 990                         slot = EvalPlanQualNext(estate);
 991                         if (TupIsNull(slot))
 992                                 slot = ExecProcNode(planstate);
 993                 }
 994                 else
 995                         slot = ExecProcNode(planstate);
 996
 997                 /*
 998                  * if the tuple is null, then we assume there is nothing more to
 999                  * process so we just return null...
1000                  */
1001                 if (TupIsNull(slot))
1002                 {
1003                         result = NULL;
1004                         break;
1005                 }
1006
1007                 /*
1008                  * if we have a junk filter, then project a new tuple with the
1009                  * junk removed.
1010                  *
1011                  * Store this new "clean" tuple in the junkfilter's resultSlot.
1012                  * (Formerly, we stored it back over the "dirty" tuple, which is
1013                  * WRONG because that tuple slot has the wrong descriptor.)
1014                  *
1015                  * Also, extract all the junk information we need.
1016                  */
1017                 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
1018                 {
1019                         Datum           datum;
1020                         HeapTuple       newTuple;
1021                         bool            isNull;
1022
1023                         /*
1024                          * extract the 'ctid' junk attribute.
1025                          */
1026                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
1027                         {
1028                                 if (!ExecGetJunkAttribute(junkfilter,
1029                                                                                   slot,
1030                                                                                   "ctid",
1031                                                                                   &datum,
1032                                                                                   &isNull))
1033                                         elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1034
1035                                 /* shouldn't ever get a null result... */
1036                                 if (isNull)
1037                                         elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1038
1039                                 tupleid = (ItemPointer) DatumGetPointer(datum);
1040                                 tuple_ctid = *tupleid;  /* make sure we don't free the
1041                                                                                  * ctid!! */
1042                                 tupleid = &tuple_ctid;
1043                         }
1044                         else if (estate->es_rowMark != NIL)
1045                         {
1046                                 List       *l;
1047
1048                 lmark:  ;
1049                                 foreach(l, estate->es_rowMark)
1050                                 {
1051                                         execRowMark *erm = lfirst(l);
1052                                         Buffer          buffer;
1053                                         HeapTupleData tuple;
1054                                         TupleTableSlot *newSlot;
1055                                         int                     test;
1056
1057                                         if (!ExecGetJunkAttribute(junkfilter,
1058                                                                                           slot,
1059                                                                                           erm->resname,
1060                                                                                           &datum,
1061                                                                                           &isNull))
1062                                                 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1063                                                          erm->resname);
1064
1065                                         /* shouldn't ever get a null result... */
1066                                         if (isNull)
1067                                                 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1068                                                          erm->resname);
1069
1070                                         tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1071                                         test = heap_mark4update(erm->relation, &tuple, &buffer,
1072                                                                                         estate->es_snapshot->curcid);
1073                                         ReleaseBuffer(buffer);
1074                                         switch (test)
1075                                         {
1076                                                 case HeapTupleSelfUpdated:
1077                                                         /* treat it as deleted; do not process */
1078                                                         goto lnext;
1079
1080                                                 case HeapTupleMayBeUpdated:
1081                                                         break;
1082
1083                                                 case HeapTupleUpdated:
1084                                                         if (XactIsoLevel == XACT_SERIALIZABLE)
1085                                                                 elog(ERROR, "Can't serialize access due to concurrent update");
1086                                                         if (!(ItemPointerEquals(&(tuple.t_self),
1087                                                                   (ItemPointer) DatumGetPointer(datum))))
1088                                                         {
1089                                                                 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1090                                                                 if (!(TupIsNull(newSlot)))
1091                                                                 {
1092                                                                         slot = newSlot;
1093                                                                         estate->es_useEvalPlan = true;
1094                                                                         goto lmark;
1095                                                                 }
1096                                                         }
1097
1098                                                         /*
1099                                                          * if tuple was deleted or PlanQual failed for
1100                                                          * updated tuple - we must not return this
1101                                                          * tuple!
1102                                                          */
1103                                                         goto lnext;
1104
1105                                                 default:
1106                                                         elog(ERROR, "Unknown status %u from heap_mark4update", test);
1107                                                         return (NULL);
1108                                         }
1109                                 }
1110                         }
1111
1112                         /*
1113                          * Finally create a new "clean" tuple with all junk attributes
1114                          * removed
1115                          */
1116                         newTuple = ExecRemoveJunk(junkfilter, slot);
1117
1118                         slot = ExecStoreTuple(newTuple,         /* tuple to store */
1119                                                                   junkfilter->jf_resultSlot,    /* dest slot */
1120                                                                   InvalidBuffer,                /* this tuple has no
1121                                                                                                                  * buffer */
1122                                                                   true);                /* tuple should be pfreed */
1123                 }
1124
1125                 /*
1126                  * now that we have a tuple, do the appropriate thing with it..
1127                  * either return it to the user, add it to a relation someplace,
1128                  * delete it from a relation, or modify some of its attributes.
1129                  */
1130                 switch (operation)
1131                 {
1132                         case CMD_SELECT:
1133                                 ExecSelect(slot,        /* slot containing tuple */
1134                                                    destfunc,    /* destination's tuple-receiver
1135                                                                                  * obj */
1136                                                    estate);
1137                                 result = slot;
1138                                 break;
1139
1140                         case CMD_INSERT:
1141                                 ExecInsert(slot, tupleid, estate);
1142                                 result = NULL;
1143                                 break;
1144
1145                         case CMD_DELETE:
1146                                 ExecDelete(slot, tupleid, estate);
1147                                 result = NULL;
1148                                 break;
1149
1150                         case CMD_UPDATE:
1151                                 ExecUpdate(slot, tupleid, estate);
1152                                 result = NULL;
1153                                 break;
1154
1155                         default:
1156                                 elog(LOG, "ExecutePlan: unknown operation in queryDesc");
1157                                 result = NULL;
1158                                 break;
1159                 }
1160
1161                 /*
1162                  * check our tuple count.. if we've processed the proper number
1163                  * then quit, else loop again and process more tuples.  Zero
1164                  * numberTuples means no limit.
1165                  */
1166                 current_tuple_count++;
1167                 if (numberTuples && numberTuples == current_tuple_count)
1168                         break;
1169         }
1170
1171         /*
1172          * Process AFTER EACH STATEMENT triggers
1173          */
1174         switch (operation)
1175         {
1176                 case CMD_UPDATE:
1177                         ExecASUpdateTriggers(estate, estate->es_result_relation_info);
1178                         break;
1179                 case CMD_DELETE:
1180                         ExecASDeleteTriggers(estate, estate->es_result_relation_info);
1181                         break;
1182                 case CMD_INSERT:
1183                         ExecASInsertTriggers(estate, estate->es_result_relation_info);
1184                         break;
1185                 default:
1186                         /* do nothing */
1187                         break;
1188         }
1189
1190         /*
1191          * here, result is either a slot containing a tuple in the case of a
1192          * SELECT or NULL otherwise.
1193          */
1194         return result;
1195 }
1196
1197 /* ----------------------------------------------------------------
1198  *              ExecSelect
1199  *
1200  *              SELECTs are easy.. we just pass the tuple to the appropriate
1201  *              print function.  The only complexity is when we do a
1202  *              "SELECT INTO", in which case we insert the tuple into
1203  *              the appropriate relation (note: this is a newly created relation
1204  *              so we don't need to worry about indices or locks.)
1205  * ----------------------------------------------------------------
1206  */
1207 static void
1208 ExecSelect(TupleTableSlot *slot,
1209                    DestReceiver *destfunc,
1210                    EState *estate)
1211 {
1212         HeapTuple       tuple;
1213         TupleDesc       attrtype;
1214
1215         /*
1216          * get the heap tuple out of the tuple table slot
1217          */
1218         tuple = slot->val;
1219         attrtype = slot->ttc_tupleDescriptor;
1220
1221         /*
1222          * insert the tuple into the "into relation"
1223          */
1224         if (estate->es_into_relation_descriptor != NULL)
1225         {
1226                 heap_insert(estate->es_into_relation_descriptor, tuple,
1227                                         estate->es_snapshot->curcid);
1228                 IncrAppended();
1229         }
1230
1231         /*
1232          * send the tuple to the front end (or the screen)
1233          */
1234         (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1235         IncrRetrieved();
1236         (estate->es_processed)++;
1237 }
1238
1239 /* ----------------------------------------------------------------
1240  *              ExecInsert
1241  *
1242  *              INSERTs are trickier.. we have to insert the tuple into
1243  *              the base relation and insert appropriate tuples into the
1244  *              index relations.
1245  * ----------------------------------------------------------------
1246  */
1247 static void
1248 ExecInsert(TupleTableSlot *slot,
1249                    ItemPointer tupleid,
1250                    EState *estate)
1251 {
1252         HeapTuple       tuple;
1253         ResultRelInfo *resultRelInfo;
1254         Relation        resultRelationDesc;
1255         int                     numIndices;
1256         Oid                     newId;
1257
1258         /*
1259          * get the heap tuple out of the tuple table slot
1260          */
1261         tuple = slot->val;
1262
1263         /*
1264          * get information on the (current) result relation
1265          */
1266         resultRelInfo = estate->es_result_relation_info;
1267         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1268
1269         /* BEFORE ROW INSERT Triggers */
1270         if (resultRelInfo->ri_TrigDesc &&
1271                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1272         {
1273                 HeapTuple       newtuple;
1274
1275                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1276
1277                 if (newtuple == NULL)   /* "do nothing" */
1278                         return;
1279
1280                 if (newtuple != tuple)  /* modified by Trigger(s) */
1281                 {
1282                         /*
1283                          * Insert modified tuple into tuple table slot, replacing the
1284                          * original.  We assume that it was allocated in per-tuple
1285                          * memory context, and therefore will go away by itself. The
1286                          * tuple table slot should not try to clear it.
1287                          */
1288                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1289                         tuple = newtuple;
1290                 }
1291         }
1292
1293         /*
1294          * Check the constraints of the tuple
1295          */
1296         if (resultRelationDesc->rd_att->constr)
1297                 ExecConstraints("ExecInsert", resultRelInfo, slot, estate);
1298
1299         /*
1300          * insert the tuple
1301          */
1302         newId = heap_insert(resultRelationDesc, tuple,
1303                                                 estate->es_snapshot->curcid);
1304
1305         IncrAppended();
1306         (estate->es_processed)++;
1307         estate->es_lastoid = newId;
1308         setLastTid(&(tuple->t_self));
1309
1310         /*
1311          * process indices
1312          *
1313          * Note: heap_insert adds a new tuple to a relation.  As a side effect,
1314          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1315          * field.
1316          */
1317         numIndices = resultRelInfo->ri_NumIndices;
1318         if (numIndices > 0)
1319                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1320
1321         /* AFTER ROW INSERT Triggers */
1322         ExecARInsertTriggers(estate, resultRelInfo, tuple);
1323 }
1324
1325 /* ----------------------------------------------------------------
1326  *              ExecDelete
1327  *
1328  *              DELETE is like UPDATE, we delete the tuple and its
1329  *              index tuples.
1330  * ----------------------------------------------------------------
1331  */
1332 static void
1333 ExecDelete(TupleTableSlot *slot,
1334                    ItemPointer tupleid,
1335                    EState *estate)
1336 {
1337         ResultRelInfo *resultRelInfo;
1338         Relation        resultRelationDesc;
1339         ItemPointerData ctid;
1340         int                     result;
1341
1342         /*
1343          * get information on the (current) result relation
1344          */
1345         resultRelInfo = estate->es_result_relation_info;
1346         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1347
1348         /* BEFORE ROW DELETE Triggers */
1349         if (resultRelInfo->ri_TrigDesc &&
1350           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1351         {
1352                 bool            dodelete;
1353
1354                 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1355
1356                 if (!dodelete)                  /* "do nothing" */
1357                         return;
1358         }
1359
1360         /*
1361          * delete the tuple
1362          */
1363 ldelete:;
1364         result = heap_delete(resultRelationDesc, tupleid,
1365                                                  &ctid,
1366                                                  estate->es_snapshot->curcid);
1367         switch (result)
1368         {
1369                 case HeapTupleSelfUpdated:
1370                         /* already deleted by self; nothing to do */
1371                         return;
1372
1373                 case HeapTupleMayBeUpdated:
1374                         break;
1375
1376                 case HeapTupleUpdated:
1377                         if (XactIsoLevel == XACT_SERIALIZABLE)
1378                                 elog(ERROR, "Can't serialize access due to concurrent update");
1379                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1380                         {
1381                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1382                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1383
1384                                 if (!TupIsNull(epqslot))
1385                                 {
1386                                         *tupleid = ctid;
1387                                         goto ldelete;
1388                                 }
1389                         }
1390                         /* tuple already deleted; nothing to do */
1391                         return;
1392
1393                 default:
1394                         elog(ERROR, "Unknown status %u from heap_delete", result);
1395                         return;
1396         }
1397
1398         IncrDeleted();
1399         (estate->es_processed)++;
1400
1401         /*
1402          * Note: Normally one would think that we have to delete index tuples
1403          * associated with the heap tuple now..
1404          *
1405          * ... but in POSTGRES, we have no need to do this because the vacuum
1406          * daemon automatically opens an index scan and deletes index tuples
1407          * when it finds deleted heap tuples. -cim 9/27/89
1408          */
1409
1410         /* AFTER ROW DELETE Triggers */
1411         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1412 }
1413
1414 /* ----------------------------------------------------------------
1415  *              ExecUpdate
1416  *
1417  *              note: we can't run UPDATE queries with transactions
1418  *              off because UPDATEs are actually INSERTs and our
1419  *              scan will mistakenly loop forever, updating the tuple
1420  *              it just inserted..      This should be fixed but until it
1421  *              is, we don't want to get stuck in an infinite loop
1422  *              which corrupts your database..
1423  * ----------------------------------------------------------------
1424  */
1425 static void
1426 ExecUpdate(TupleTableSlot *slot,
1427                    ItemPointer tupleid,
1428                    EState *estate)
1429 {
1430         HeapTuple       tuple;
1431         ResultRelInfo *resultRelInfo;
1432         Relation        resultRelationDesc;
1433         ItemPointerData ctid;
1434         int                     result;
1435         int                     numIndices;
1436
1437         /*
1438          * abort the operation if not running transactions
1439          */
1440         if (IsBootstrapProcessingMode())
1441         {
1442                 elog(WARNING, "ExecUpdate: UPDATE can't run without transactions");
1443                 return;
1444         }
1445
1446         /*
1447          * get the heap tuple out of the tuple table slot
1448          */
1449         tuple = slot->val;
1450
1451         /*
1452          * get information on the (current) result relation
1453          */
1454         resultRelInfo = estate->es_result_relation_info;
1455         resultRelationDesc = resultRelInfo->ri_RelationDesc;
1456
1457         /* BEFORE ROW UPDATE Triggers */
1458         if (resultRelInfo->ri_TrigDesc &&
1459           resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1460         {
1461                 HeapTuple       newtuple;
1462
1463                 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1464                                                                                 tupleid, tuple);
1465
1466                 if (newtuple == NULL)   /* "do nothing" */
1467                         return;
1468
1469                 if (newtuple != tuple)  /* modified by Trigger(s) */
1470                 {
1471                         /*
1472                          * Insert modified tuple into tuple table slot, replacing the
1473                          * original.  We assume that it was allocated in per-tuple
1474                          * memory context, and therefore will go away by itself. The
1475                          * tuple table slot should not try to clear it.
1476                          */
1477                         ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1478                         tuple = newtuple;
1479                 }
1480         }
1481
1482         /*
1483          * Check the constraints of the tuple
1484          *
1485          * If we generate a new candidate tuple after EvalPlanQual testing, we
1486          * must loop back here and recheck constraints.  (We don't need to
1487          * redo triggers, however.      If there are any BEFORE triggers then
1488          * trigger.c will have done mark4update to lock the correct tuple, so
1489          * there's no need to do them again.)
1490          */
1491 lreplace:;
1492         if (resultRelationDesc->rd_att->constr)
1493                 ExecConstraints("ExecUpdate", resultRelInfo, slot, estate);
1494
1495         /*
1496          * replace the heap tuple
1497          */
1498         result = heap_update(resultRelationDesc, tupleid, tuple,
1499                                                  &ctid,
1500                                                  estate->es_snapshot->curcid);
1501         switch (result)
1502         {
1503                 case HeapTupleSelfUpdated:
1504                         /* already deleted by self; nothing to do */
1505                         return;
1506
1507                 case HeapTupleMayBeUpdated:
1508                         break;
1509
1510                 case HeapTupleUpdated:
1511                         if (XactIsoLevel == XACT_SERIALIZABLE)
1512                                 elog(ERROR, "Can't serialize access due to concurrent update");
1513                         else if (!(ItemPointerEquals(tupleid, &ctid)))
1514                         {
1515                                 TupleTableSlot *epqslot = EvalPlanQual(estate,
1516                                                            resultRelInfo->ri_RangeTableIndex, &ctid);
1517
1518                                 if (!TupIsNull(epqslot))
1519                                 {
1520                                         *tupleid = ctid;
1521                                         tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1522                                         slot = ExecStoreTuple(tuple,
1523                                                                         estate->es_junkFilter->jf_resultSlot,
1524                                                                                   InvalidBuffer, true);
1525                                         goto lreplace;
1526                                 }
1527                         }
1528                         /* tuple already deleted; nothing to do */
1529                         return;
1530
1531                 default:
1532                         elog(ERROR, "Unknown status %u from heap_update", result);
1533                         return;
1534         }
1535
1536         IncrReplaced();
1537         (estate->es_processed)++;
1538
1539         /*
1540          * Note: instead of having to update the old index tuples associated
1541          * with the heap tuple, all we do is form and insert new index tuples.
1542          * This is because UPDATEs are actually DELETEs and INSERTs and index
1543          * tuple deletion is done automagically by the vacuum daemon. All we
1544          * do is insert new index tuples.  -cim 9/27/89
1545          */
1546
1547         /*
1548          * process indices
1549          *
1550          * heap_update updates a tuple in the base relation by invalidating it
1551          * and then inserting a new tuple to the relation.      As a side effect,
1552          * the tupleid of the new tuple is placed in the new tuple's t_ctid
1553          * field.  So we now insert index tuples using the new tupleid stored
1554          * there.
1555          */
1556
1557         numIndices = resultRelInfo->ri_NumIndices;
1558         if (numIndices > 0)
1559                 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1560
1561         /* AFTER ROW UPDATE Triggers */
1562         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1563 }
1564
1565 static char *
1566 ExecRelCheck(ResultRelInfo *resultRelInfo,
1567                          TupleTableSlot *slot, EState *estate)
1568 {
1569         Relation        rel = resultRelInfo->ri_RelationDesc;
1570         int                     ncheck = rel->rd_att->constr->num_check;
1571         ConstrCheck *check = rel->rd_att->constr->check;
1572         ExprContext *econtext;
1573         MemoryContext oldContext;
1574         List       *qual;
1575         int                     i;
1576
1577         /*
1578          * If first time through for this result relation, build expression
1579          * nodetrees for rel's constraint expressions.  Keep them in the
1580          * per-query memory context so they'll survive throughout the query.
1581          */
1582         if (resultRelInfo->ri_ConstraintExprs == NULL)
1583         {
1584                 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1585                 resultRelInfo->ri_ConstraintExprs =
1586                         (List **) palloc(ncheck * sizeof(List *));
1587                 for (i = 0; i < ncheck; i++)
1588                 {
1589                         qual = (List *) stringToNode(check[i].ccbin);
1590                         resultRelInfo->ri_ConstraintExprs[i] = (List *)
1591                                 ExecPrepareExpr((Expr *) qual, estate);
1592                 }
1593                 MemoryContextSwitchTo(oldContext);
1594         }
1595
1596         /*
1597          * We will use the EState's per-tuple context for evaluating
1598          * constraint expressions (creating it if it's not already there).
1599          */
1600         econtext = GetPerTupleExprContext(estate);
1601
1602         /* Arrange for econtext's scan tuple to be the tuple under test */
1603         econtext->ecxt_scantuple = slot;
1604
1605         /* And evaluate the constraints */
1606         for (i = 0; i < ncheck; i++)
1607         {
1608                 qual = resultRelInfo->ri_ConstraintExprs[i];
1609
1610                 /*
1611                  * NOTE: SQL92 specifies that a NULL result from a constraint
1612                  * expression is not to be treated as a failure.  Therefore, tell
1613                  * ExecQual to return TRUE for NULL.
1614                  */
1615                 if (!ExecQual(qual, econtext, true))
1616                         return check[i].ccname;
1617         }
1618
1619         /* NULL result means no error */
1620         return (char *) NULL;
1621 }
1622
1623 void
1624 ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
1625                                 TupleTableSlot *slot, EState *estate)
1626 {
1627         Relation        rel = resultRelInfo->ri_RelationDesc;
1628         HeapTuple       tuple = slot->val;
1629         TupleConstr *constr = rel->rd_att->constr;
1630
1631         Assert(constr);
1632
1633         if (constr->has_not_null)
1634         {
1635                 int                     natts = rel->rd_att->natts;
1636                 int                     attrChk;
1637
1638                 for (attrChk = 1; attrChk <= natts; attrChk++)
1639                 {
1640                         if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1641                                 heap_attisnull(tuple, attrChk))
1642                                 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1643                                          caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1644                 }
1645         }
1646
1647         if (constr->num_check > 0)
1648         {
1649                 char       *failed;
1650
1651                 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1652                         elog(ERROR, "%s: rejected due to CHECK constraint \"%s\" on \"%s\"",
1653                                  caller, failed, RelationGetRelationName(rel));
1654         }
1655 }
1656
1657 /*
1658  * Check a modified tuple to see if we want to process its updated version
1659  * under READ COMMITTED rules.
1660  *
1661  * See backend/executor/README for some info about how this works.
1662  */
1663 TupleTableSlot *
1664 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1665 {
1666         evalPlanQual *epq;
1667         EState     *epqstate;
1668         Relation        relation;
1669         HeapTupleData tuple;
1670         HeapTuple       copyTuple = NULL;
1671         bool            endNode;
1672
1673         Assert(rti != 0);
1674
1675         /*
1676          * find relation containing target tuple
1677          */
1678         if (estate->es_result_relation_info != NULL &&
1679                 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1680                 relation = estate->es_result_relation_info->ri_RelationDesc;
1681         else
1682         {
1683                 List       *l;
1684
1685                 relation = NULL;
1686                 foreach(l, estate->es_rowMark)
1687                 {
1688                         if (((execRowMark *) lfirst(l))->rti == rti)
1689                         {
1690                                 relation = ((execRowMark *) lfirst(l))->relation;
1691                                 break;
1692                         }
1693                 }
1694                 if (relation == NULL)
1695                         elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1696         }
1697
1698         /*
1699          * fetch tid tuple
1700          *
1701          * Loop here to deal with updated or busy tuples
1702          */
1703         tuple.t_self = *tid;
1704         for (;;)
1705         {
1706                 Buffer          buffer;
1707
1708                 if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
1709                 {
1710                         TransactionId xwait = SnapshotDirty->xmax;
1711
1712                         if (TransactionIdIsValid(SnapshotDirty->xmin))
1713                                 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1714
1715                         /*
1716                          * If tuple is being updated by other transaction then we have
1717                          * to wait for its commit/abort.
1718                          */
1719                         if (TransactionIdIsValid(xwait))
1720                         {
1721                                 ReleaseBuffer(buffer);
1722                                 XactLockTableWait(xwait);
1723                                 continue;
1724                         }
1725
1726                         /*
1727                          * We got tuple - now copy it for use by recheck query.
1728                          */
1729                         copyTuple = heap_copytuple(&tuple);
1730                         ReleaseBuffer(buffer);
1731                         break;
1732                 }
1733
1734                 /*
1735                  * Oops! Invalid tuple. Have to check is it updated or deleted.
1736                  * Note that it's possible to get invalid SnapshotDirty->tid if
1737                  * tuple updated by this transaction. Have we to check this ?
1738                  */
1739                 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1740                         !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1741                 {
1742                         /* updated, so look at the updated copy */
1743                         tuple.t_self = SnapshotDirty->tid;
1744                         continue;
1745                 }
1746
1747                 /*
1748                  * Deleted or updated by this transaction; forget it.
1749                  */
1750                 return NULL;
1751         }
1752
1753         /*
1754          * For UPDATE/DELETE we have to return tid of actual row we're
1755          * executing PQ for.
1756          */
1757         *tid = tuple.t_self;
1758
1759         /*
1760          * Need to run a recheck subquery.      Find or create a PQ stack entry.
1761          */
1762         epq = estate->es_evalPlanQual;
1763         endNode = true;
1764
1765         if (epq != NULL && epq->rti == 0)
1766         {
1767                 /* Top PQ stack entry is idle, so re-use it */
1768                 Assert(!(estate->es_useEvalPlan) && epq->next == NULL);
1769                 epq->rti = rti;
1770                 endNode = false;
1771         }
1772
1773         /*
1774          * If this is request for another RTE - Ra, - then we have to check
1775          * wasn't PlanQual requested for Ra already and if so then Ra' row was
1776          * updated again and we have to re-start old execution for Ra and
1777          * forget all what we done after Ra was suspended. Cool? -:))
1778          */
1779         if (epq != NULL && epq->rti != rti &&
1780                 epq->estate->es_evTuple[rti - 1] != NULL)
1781         {
1782                 do
1783                 {
1784                         evalPlanQual *oldepq;
1785
1786                         /* stop execution */
1787                         EvalPlanQualStop(epq);
1788                         /* pop previous PlanQual from the stack */
1789                         oldepq = epq->next;
1790                         Assert(oldepq && oldepq->rti != 0);
1791                         /* push current PQ to freePQ stack */
1792                         oldepq->free = epq;
1793                         epq = oldepq;
1794                         estate->es_evalPlanQual = epq;
1795                 } while (epq->rti != rti);
1796         }
1797
1798         /*
1799          * If we are requested for another RTE then we have to suspend
1800          * execution of current PlanQual and start execution for new one.
1801          */
1802         if (epq == NULL || epq->rti != rti)
1803         {
1804                 /* try to reuse plan used previously */
1805                 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1806
1807                 if (newepq == NULL)             /* first call or freePQ stack is empty */
1808                 {
1809                         newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual));
1810                         newepq->free = NULL;
1811                         newepq->estate = NULL;
1812                         newepq->planstate = NULL;
1813                 }
1814                 else
1815                 {
1816                         /* recycle previously used PlanQual */
1817                         Assert(newepq->estate == NULL);
1818                         epq->free = NULL;
1819                 }
1820                 /* push current PQ to the stack */
1821                 newepq->next = epq;
1822                 epq = newepq;
1823                 estate->es_evalPlanQual = epq;
1824                 epq->rti = rti;
1825                 endNode = false;
1826         }
1827
1828         Assert(epq->rti == rti);
1829
1830         /*
1831          * Ok - we're requested for the same RTE.  Unfortunately we still have
1832          * to end and restart execution of the plan, because ExecReScan
1833          * wouldn't ensure that upper plan nodes would reset themselves.  We
1834          * could make that work if insertion of the target tuple were
1835          * integrated with the Param mechanism somehow, so that the upper plan
1836          * nodes know that their children's outputs have changed.
1837          *
1838          * Note that the stack of free evalPlanQual nodes is quite useless at
1839          * the moment, since it only saves us from pallocing/releasing the
1840          * evalPlanQual nodes themselves.  But it will be useful once we
1841          * implement ReScan instead of end/restart for re-using PlanQual nodes.
1842          */
1843         if (endNode)
1844         {
1845                 /* stop execution */
1846                 EvalPlanQualStop(epq);
1847         }
1848
1849         /*
1850          * Initialize new recheck query.
1851          *
1852          * Note: if we were re-using PlanQual plans via ExecReScan, we'd need
1853          * to instead copy down changeable state from the top plan (including
1854          * es_result_relation_info, es_junkFilter) and reset locally changeable
1855          * state in the epq (including es_param_exec_vals, es_evTupleNull).
1856          */
1857         EvalPlanQualStart(epq, estate, epq->next);
1858
1859         /*
1860          * free old RTE' tuple, if any, and store target tuple where
1861          * relation's scan node will see it
1862          */
1863         epqstate = epq->estate;
1864         if (epqstate->es_evTuple[rti - 1] != NULL)
1865                 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1866         epqstate->es_evTuple[rti - 1] = copyTuple;
1867
1868         return EvalPlanQualNext(estate);
1869 }
1870
1871 static TupleTableSlot *
1872 EvalPlanQualNext(EState *estate)
1873 {
1874         evalPlanQual *epq = estate->es_evalPlanQual;
1875         MemoryContext oldcontext;
1876         TupleTableSlot *slot;
1877
1878         Assert(epq->rti != 0);
1879
1880 lpqnext:;
1881         oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt);
1882         slot = ExecProcNode(epq->planstate);
1883         MemoryContextSwitchTo(oldcontext);
1884
1885         /*
1886          * No more tuples for this PQ. Continue previous one.
1887          */
1888         if (TupIsNull(slot))
1889         {
1890                 evalPlanQual *oldepq;
1891
1892                 /* stop execution */
1893                 EvalPlanQualStop(epq);
1894                 /* pop old PQ from the stack */
1895                 oldepq = epq->next;
1896                 if (oldepq == NULL)
1897                 {
1898                         /* this is the first (oldest) PQ - mark as free */
1899                         epq->rti = 0;
1900                         estate->es_useEvalPlan = false;
1901                         /* and continue Query execution */
1902                         return (NULL);
1903                 }
1904                 Assert(oldepq->rti != 0);
1905                 /* push current PQ to freePQ stack */
1906                 oldepq->free = epq;
1907                 epq = oldepq;
1908                 estate->es_evalPlanQual = epq;
1909                 goto lpqnext;
1910         }
1911
1912         return (slot);
1913 }
1914
1915 static void
1916 EndEvalPlanQual(EState *estate)
1917 {
1918         evalPlanQual *epq = estate->es_evalPlanQual;
1919
1920         if (epq->rti == 0)                      /* plans already shutdowned */
1921         {
1922                 Assert(epq->next == NULL);
1923                 return;
1924         }
1925
1926         for (;;)
1927         {
1928                 evalPlanQual *oldepq;
1929
1930                 /* stop execution */
1931                 EvalPlanQualStop(epq);
1932                 /* pop old PQ from the stack */
1933                 oldepq = epq->next;
1934                 if (oldepq == NULL)
1935                 {
1936                         /* this is the first (oldest) PQ - mark as free */
1937                         epq->rti = 0;
1938                         estate->es_useEvalPlan = false;
1939                         break;
1940                 }
1941                 Assert(oldepq->rti != 0);
1942                 /* push current PQ to freePQ stack */
1943                 oldepq->free = epq;
1944                 epq = oldepq;
1945                 estate->es_evalPlanQual = epq;
1946         }
1947 }
1948
1949 /*
1950  * Start execution of one level of PlanQual.
1951  *
1952  * This is a cut-down version of ExecutorStart(): we copy some state from
1953  * the top-level estate rather than initializing it fresh.
1954  */
1955 static void
1956 EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
1957 {
1958         EState     *epqstate;
1959         int                     rtsize;
1960         MemoryContext oldcontext;
1961
1962         rtsize = length(estate->es_range_table);
1963
1964         epq->estate = epqstate = CreateExecutorState();
1965
1966         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
1967
1968         /*
1969          * The epqstates share the top query's copy of unchanging state such
1970          * as the snapshot, rangetable, result-rel info, and external Param info.
1971          * They need their own copies of local state, including a tuple table,
1972          * es_param_exec_vals, etc.
1973          */
1974         epqstate->es_direction = ForwardScanDirection;
1975         epqstate->es_snapshot = estate->es_snapshot;
1976         epqstate->es_range_table = estate->es_range_table;
1977         epqstate->es_result_relations = estate->es_result_relations;
1978         epqstate->es_num_result_relations = estate->es_num_result_relations;
1979         epqstate->es_result_relation_info = estate->es_result_relation_info;
1980         epqstate->es_junkFilter = estate->es_junkFilter;
1981         epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor;
1982         epqstate->es_param_list_info = estate->es_param_list_info;
1983         if (estate->es_topPlan->nParamExec > 0)
1984                 epqstate->es_param_exec_vals = (ParamExecData *)
1985                         palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
1986         epqstate->es_rowMark = estate->es_rowMark;
1987         epqstate->es_instrument = estate->es_instrument;
1988         epqstate->es_force_oids = estate->es_force_oids;
1989         epqstate->es_topPlan = estate->es_topPlan;
1990         /*
1991          * Each epqstate must have its own es_evTupleNull state, but
1992          * all the stack entries share es_evTuple state.  This allows
1993          * sub-rechecks to inherit the value being examined by an
1994          * outer recheck.
1995          */
1996         epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool));
1997         if (priorepq == NULL)
1998                 /* first PQ stack entry */
1999                 epqstate->es_evTuple = (HeapTuple *)
2000                         palloc0(rtsize * sizeof(HeapTuple));
2001         else
2002                 /* later stack entries share the same storage */
2003                 epqstate->es_evTuple = priorepq->estate->es_evTuple;
2004
2005         epqstate->es_tupleTable =
2006                 ExecCreateTupleTable(estate->es_tupleTable->size);
2007
2008         epq->planstate = ExecInitNode(estate->es_topPlan, epqstate);
2009
2010         MemoryContextSwitchTo(oldcontext);
2011 }
2012
2013 /*
2014  * End execution of one level of PlanQual.
2015  *
2016  * This is a cut-down version of ExecutorEnd(); basically we want to do most
2017  * of the normal cleanup, but *not* close result relations (which we are
2018  * just sharing from the outer query).
2019  */
2020 static void
2021 EvalPlanQualStop(evalPlanQual *epq)
2022 {
2023         EState     *epqstate = epq->estate;
2024         MemoryContext oldcontext;
2025
2026         oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt);
2027
2028         ExecEndNode(epq->planstate);
2029
2030         ExecDropTupleTable(epqstate->es_tupleTable, true);
2031         epqstate->es_tupleTable = NULL;
2032
2033         if (epqstate->es_evTuple[epq->rti - 1] != NULL)
2034         {
2035                 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
2036                 epqstate->es_evTuple[epq->rti - 1] = NULL;
2037         }
2038
2039         MemoryContextSwitchTo(oldcontext);
2040
2041         FreeExecutorState(epqstate);
2042
2043         epq->estate = NULL;
2044         epq->planstate = NULL;
2045 }