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

   1 /*-------------------------------------------------------------------------
   2  *
   3  * nodeSubplan.c
   4  *        routines to support subselects
   5  *
   6  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  * IDENTIFICATION
  10  *        $PostgreSQL: pgsql/src/backend/executor/nodeSubplan.c,v 1.76 2006/06/28 17:05:49 tgl Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 /*
  15  *       INTERFACE ROUTINES
  16  *              ExecSubPlan  - process a subselect
  17  *              ExecInitSubPlan - initialize a subselect
  18  *              ExecEndSubPlan  - shut down a subselect
  19  */
  20 #include "postgres.h"
  21
  22 #include "access/heapam.h"
  23 #include "executor/executor.h"
  24 #include "executor/nodeSubplan.h"
  25 #include "nodes/makefuncs.h"
  26 #include "optimizer/clauses.h"
  27 #include "parser/parse_expr.h"
  28 #include "utils/array.h"
  29 #include "utils/datum.h"
  30 #include "utils/lsyscache.h"
  31 #include "utils/memutils.h"
  32
  33
  34 static Datum ExecHashSubPlan(SubPlanState *node,
  35                                 ExprContext *econtext,
  36                                 bool *isNull);
  37 static Datum ExecScanSubPlan(SubPlanState *node,
  38                                 ExprContext *econtext,
  39                                 bool *isNull);
  40 static void buildSubPlanHash(SubPlanState *node);
  41 static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot);
  42 static bool slotAllNulls(TupleTableSlot *slot);
  43 static bool slotNoNulls(TupleTableSlot *slot);
  44
  45
  46 /* ----------------------------------------------------------------
  47  *              ExecSubPlan
  48  * ----------------------------------------------------------------
  49  */
  50 Datum
  51 ExecSubPlan(SubPlanState *node,
  52                         ExprContext *econtext,
  53                         bool *isNull,
  54                         ExprDoneCond *isDone)
  55 {
  56         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
  57
  58         /* Set default values for result flags: non-null, not a set result */
  59         *isNull = false;
  60         if (isDone)
  61                 *isDone = ExprSingleResult;
  62
  63         if (subplan->setParam != NIL)
  64                 elog(ERROR, "cannot set parent params from subquery");
  65
  66         if (subplan->useHashTable)
  67                 return ExecHashSubPlan(node, econtext, isNull);
  68         else
  69                 return ExecScanSubPlan(node, econtext, isNull);
  70 }
  71
  72 /*
  73  * ExecHashSubPlan: store subselect result in an in-memory hash table
  74  */
  75 static Datum
  76 ExecHashSubPlan(SubPlanState *node,
  77                                 ExprContext *econtext,
  78                                 bool *isNull)
  79 {
  80         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
  81         PlanState  *planstate = node->planstate;
  82         ExprContext *innerecontext = node->innerecontext;
  83         TupleTableSlot *slot;
  84
  85         /* Shouldn't have any direct correlation Vars */
  86         if (subplan->parParam != NIL || node->args != NIL)
  87                 elog(ERROR, "hashed subplan with direct correlation not supported");
  88
  89         /*
  90          * If first time through or we need to rescan the subplan, build the hash
  91          * table.
  92          */
  93         if (node->hashtable == NULL || planstate->chgParam != NULL)
  94                 buildSubPlanHash(node);
  95
  96         /*
  97          * The result for an empty subplan is always FALSE; no need to evaluate
  98          * lefthand side.
  99          */
 100         *isNull = false;
 101         if (!node->havehashrows && !node->havenullrows)
 102                 return BoolGetDatum(false);
 103
 104         /*
 105          * Evaluate lefthand expressions and form a projection tuple. First we
 106          * have to set the econtext to use (hack alert!).
 107          */
 108         node->projLeft->pi_exprContext = econtext;
 109         slot = ExecProject(node->projLeft, NULL);
 110
 111         /*
 112          * Note: because we are typically called in a per-tuple context, we have
 113          * to explicitly clear the projected tuple before returning. Otherwise,
 114          * we'll have a double-free situation: the per-tuple context will probably
 115          * be reset before we're called again, and then the tuple slot will think
 116          * it still needs to free the tuple.
 117          */
 118
 119         /*
 120          * Since the hashtable routines will use innerecontext's per-tuple memory
 121          * as working memory, be sure to reset it for each tuple.
 122          */
 123         ResetExprContext(innerecontext);
 124
 125         /*
 126          * If the LHS is all non-null, probe for an exact match in the main hash
 127          * table.  If we find one, the result is TRUE. Otherwise, scan the
 128          * partly-null table to see if there are any rows that aren't provably
 129          * unequal to the LHS; if so, the result is UNKNOWN.  (We skip that part
 130          * if we don't care about UNKNOWN.) Otherwise, the result is FALSE.
 131          *
 132          * Note: the reason we can avoid a full scan of the main hash table is
 133          * that the combining operators are assumed never to yield NULL when both
 134          * inputs are non-null.  If they were to do so, we might need to produce
 135          * UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the
 136          * LHS to some main-table entry --- which is a comparison we will not even
 137          * make, unless there's a chance match of hash keys.
 138          */
 139         if (slotNoNulls(slot))
 140         {
 141                 if (node->havehashrows &&
 142                         LookupTupleHashEntry(node->hashtable, slot, NULL) != NULL)
 143                 {
 144                         ExecClearTuple(slot);
 145                         return BoolGetDatum(true);
 146                 }
 147                 if (node->havenullrows &&
 148                         findPartialMatch(node->hashnulls, slot))
 149                 {
 150                         ExecClearTuple(slot);
 151                         *isNull = true;
 152                         return BoolGetDatum(false);
 153                 }
 154                 ExecClearTuple(slot);
 155                 return BoolGetDatum(false);
 156         }
 157
 158         /*
 159          * When the LHS is partly or wholly NULL, we can never return TRUE. If we
 160          * don't care about UNKNOWN, just return FALSE.  Otherwise, if the LHS is
 161          * wholly NULL, immediately return UNKNOWN.  (Since the combining
 162          * operators are strict, the result could only be FALSE if the sub-select
 163          * were empty, but we already handled that case.) Otherwise, we must scan
 164          * both the main and partly-null tables to see if there are any rows that
 165          * aren't provably unequal to the LHS; if so, the result is UNKNOWN.
 166          * Otherwise, the result is FALSE.
 167          */
 168         if (node->hashnulls == NULL)
 169         {
 170                 ExecClearTuple(slot);
 171                 return BoolGetDatum(false);
 172         }
 173         if (slotAllNulls(slot))
 174         {
 175                 ExecClearTuple(slot);
 176                 *isNull = true;
 177                 return BoolGetDatum(false);
 178         }
 179         /* Scan partly-null table first, since more likely to get a match */
 180         if (node->havenullrows &&
 181                 findPartialMatch(node->hashnulls, slot))
 182         {
 183                 ExecClearTuple(slot);
 184                 *isNull = true;
 185                 return BoolGetDatum(false);
 186         }
 187         if (node->havehashrows &&
 188                 findPartialMatch(node->hashtable, slot))
 189         {
 190                 ExecClearTuple(slot);
 191                 *isNull = true;
 192                 return BoolGetDatum(false);
 193         }
 194         ExecClearTuple(slot);
 195         return BoolGetDatum(false);
 196 }
 197
 198 /*
 199  * ExecScanSubPlan: default case where we have to rescan subplan each time
 200  */
 201 static Datum
 202 ExecScanSubPlan(SubPlanState *node,
 203                                 ExprContext *econtext,
 204                                 bool *isNull)
 205 {
 206         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
 207         PlanState  *planstate = node->planstate;
 208         SubLinkType subLinkType = subplan->subLinkType;
 209         MemoryContext oldcontext;
 210         TupleTableSlot *slot;
 211         Datum           result;
 212         bool            found = false;  /* TRUE if got at least one subplan tuple */
 213         ListCell   *pvar;
 214         ListCell   *l;
 215         ArrayBuildState *astate = NULL;
 216
 217         /*
 218          * We are probably in a short-lived expression-evaluation context. Switch
 219          * to the child plan's per-query context for manipulating its chgParam,
 220          * calling ExecProcNode on it, etc.
 221          */
 222         oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
 223
 224         /*
 225          * Set Params of this plan from parent plan correlation values. (Any
 226          * calculation we have to do is done in the parent econtext, since the
 227          * Param values don't need to have per-query lifetime.)
 228          */
 229         Assert(list_length(subplan->parParam) == list_length(node->args));
 230
 231         forboth(l, subplan->parParam, pvar, node->args)
 232         {
 233                 int                     paramid = lfirst_int(l);
 234                 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 235
 236                 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
 237                                                                                            econtext,
 238                                                                                            &(prm->isnull),
 239                                                                                            NULL);
 240                 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
 241         }
 242
 243         ExecReScan(planstate, NULL);
 244
 245         /*
 246          * For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result
 247          * is boolean as are the results of the combining operators. We combine
 248          * results across tuples (if the subplan produces more than one) using OR
 249          * semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
 250          * (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.)
 251          * NULL results from the combining operators are handled according to the
 252          * usual SQL semantics for OR and AND.  The result for no input tuples is
 253          * FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
 254          * ROWCOMPARE_SUBLINK.
 255          *
 256          * For EXPR_SUBLINK we require the subplan to produce no more than one
 257          * tuple, else an error is raised. For ARRAY_SUBLINK we allow the subplan
 258          * to produce more than one tuple. In either case, if zero tuples are
 259          * produced, we return NULL. Assuming we get a tuple, we just use its
 260          * first column (there can be only one non-junk column in this case).
 261          */
 262         result = BoolGetDatum(subLinkType == ALL_SUBLINK);
 263         *isNull = false;
 264
 265         for (slot = ExecProcNode(planstate);
 266                  !TupIsNull(slot);
 267                  slot = ExecProcNode(planstate))
 268         {
 269                 TupleDesc       tdesc = slot->tts_tupleDescriptor;
 270                 Datum           rowresult;
 271                 bool            rownull;
 272                 int                     col;
 273                 ListCell   *plst;
 274
 275                 if (subLinkType == EXISTS_SUBLINK)
 276                 {
 277                         found = true;
 278                         result = BoolGetDatum(true);
 279                         break;
 280                 }
 281
 282                 if (subLinkType == EXPR_SUBLINK)
 283                 {
 284                         /* cannot allow multiple input tuples for EXPR sublink */
 285                         if (found)
 286                                 ereport(ERROR,
 287                                                 (errcode(ERRCODE_CARDINALITY_VIOLATION),
 288                                                  errmsg("more than one row returned by a subquery used as an expression")));
 289                         found = true;
 290
 291                         /*
 292                          * We need to copy the subplan's tuple in case the result is of
 293                          * pass-by-ref type --- our return value will point into this
 294                          * copied tuple!  Can't use the subplan's instance of the tuple
 295                          * since it won't still be valid after next ExecProcNode() call.
 296                          * node->curTuple keeps track of the copied tuple for eventual
 297                          * freeing.
 298                          */
 299                         MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
 300                         if (node->curTuple)
 301                                 heap_freetuple(node->curTuple);
 302                         node->curTuple = ExecCopySlotTuple(slot);
 303                         MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
 304
 305                         result = heap_getattr(node->curTuple, 1, tdesc, isNull);
 306                         /* keep scanning subplan to make sure there's only one tuple */
 307                         continue;
 308                 }
 309
 310                 if (subLinkType == ARRAY_SUBLINK)
 311                 {
 312                         Datum           dvalue;
 313                         bool            disnull;
 314
 315                         found = true;
 316                         /* stash away current value */
 317                         dvalue = slot_getattr(slot, 1, &disnull);
 318                         astate = accumArrayResult(astate, dvalue, disnull,
 319                                                                           tdesc->attrs[0]->atttypid,
 320                                                                           oldcontext);
 321                         /* keep scanning subplan to collect all values */
 322                         continue;
 323                 }
 324
 325                 /* cannot allow multiple input tuples for ROWCOMPARE sublink either */
 326                 if (subLinkType == ROWCOMPARE_SUBLINK && found)
 327                         ereport(ERROR,
 328                                         (errcode(ERRCODE_CARDINALITY_VIOLATION),
 329                                          errmsg("more than one row returned by a subquery used as an expression")));
 330
 331                 found = true;
 332
 333                 /*
 334                  * For ALL, ANY, and ROWCOMPARE sublinks, load up the Params
 335                  * representing the columns of the sub-select, and then evaluate
 336                  * the combining expression.
 337                  */
 338                 col = 1;
 339                 foreach(plst, subplan->paramIds)
 340                 {
 341                         int                     paramid = lfirst_int(plst);
 342                         ParamExecData *prmdata;
 343
 344                         prmdata = &(econtext->ecxt_param_exec_vals[paramid]);
 345                         Assert(prmdata->execPlan == NULL);
 346                         prmdata->value = slot_getattr(slot, col, &(prmdata->isnull));
 347                         col++;
 348                 }
 349
 350                 rowresult = ExecEvalExprSwitchContext(node->testexpr, econtext,
 351                                                                                           &rownull, NULL);
 352
 353                 if (subLinkType == ANY_SUBLINK)
 354                 {
 355                         /* combine across rows per OR semantics */
 356                         if (rownull)
 357                                 *isNull = true;
 358                         else if (DatumGetBool(rowresult))
 359                         {
 360                                 result = BoolGetDatum(true);
 361                                 *isNull = false;
 362                                 break;                  /* needn't look at any more rows */
 363                         }
 364                 }
 365                 else if (subLinkType == ALL_SUBLINK)
 366                 {
 367                         /* combine across rows per AND semantics */
 368                         if (rownull)
 369                                 *isNull = true;
 370                         else if (!DatumGetBool(rowresult))
 371                         {
 372                                 result = BoolGetDatum(false);
 373                                 *isNull = false;
 374                                 break;                  /* needn't look at any more rows */
 375                         }
 376                 }
 377                 else
 378                 {
 379                         /* must be ROWCOMPARE_SUBLINK */
 380                         result = rowresult;
 381                         *isNull = rownull;
 382                 }
 383         }
 384
 385         if (!found)
 386         {
 387                 /*
 388                  * deal with empty subplan result.      result/isNull were previously
 389                  * initialized correctly for all sublink types except EXPR, ARRAY, and
 390                  * ROWCOMPARE; for those, return NULL.
 391                  */
 392                 if (subLinkType == EXPR_SUBLINK ||
 393                         subLinkType == ARRAY_SUBLINK ||
 394                         subLinkType == ROWCOMPARE_SUBLINK)
 395                 {
 396                         result = (Datum) 0;
 397                         *isNull = true;
 398                 }
 399         }
 400         else if (subLinkType == ARRAY_SUBLINK)
 401         {
 402                 Assert(astate != NULL);
 403                 /* We return the result in the caller's context */
 404                 result = makeArrayResult(astate, oldcontext);
 405         }
 406
 407         MemoryContextSwitchTo(oldcontext);
 408
 409         return result;
 410 }
 411
 412 /*
 413  * buildSubPlanHash: load hash table by scanning subplan output.
 414  */
 415 static void
 416 buildSubPlanHash(SubPlanState *node)
 417 {
 418         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
 419         PlanState  *planstate = node->planstate;
 420         int                     ncols = list_length(subplan->paramIds);
 421         ExprContext *innerecontext = node->innerecontext;
 422         MemoryContext tempcxt = innerecontext->ecxt_per_tuple_memory;
 423         MemoryContext oldcontext;
 424         int                     nbuckets;
 425         TupleTableSlot *slot;
 426
 427         Assert(subplan->subLinkType == ANY_SUBLINK);
 428
 429         /*
 430          * If we already had any hash tables, destroy 'em; then create empty hash
 431          * table(s).
 432          *
 433          * If we need to distinguish accurately between FALSE and UNKNOWN (i.e.,
 434          * NULL) results of the IN operation, then we have to store subplan output
 435          * rows that are partly or wholly NULL.  We store such rows in a separate
 436          * hash table that we expect will be much smaller than the main table. (We
 437          * can use hashing to eliminate partly-null rows that are not distinct.
 438          * We keep them separate to minimize the cost of the inevitable full-table
 439          * searches; see findPartialMatch.)
 440          *
 441          * If it's not necessary to distinguish FALSE and UNKNOWN, then we don't
 442          * need to store subplan output rows that contain NULL.
 443          */
 444         MemoryContextReset(node->tablecxt);
 445         node->hashtable = NULL;
 446         node->hashnulls = NULL;
 447         node->havehashrows = false;
 448         node->havenullrows = false;
 449
 450         nbuckets = (int) ceil(planstate->plan->plan_rows);
 451         if (nbuckets < 1)
 452                 nbuckets = 1;
 453
 454         node->hashtable = BuildTupleHashTable(ncols,
 455                                                                                   node->keyColIdx,
 456                                                                                   node->eqfunctions,
 457                                                                                   node->hashfunctions,
 458                                                                                   nbuckets,
 459                                                                                   sizeof(TupleHashEntryData),
 460                                                                                   node->tablecxt,
 461                                                                                   tempcxt);
 462
 463         if (!subplan->unknownEqFalse)
 464         {
 465                 if (ncols == 1)
 466                         nbuckets = 1;           /* there can only be one entry */
 467                 else
 468                 {
 469                         nbuckets /= 16;
 470                         if (nbuckets < 1)
 471                                 nbuckets = 1;
 472                 }
 473                 node->hashnulls = BuildTupleHashTable(ncols,
 474                                                                                           node->keyColIdx,
 475                                                                                           node->eqfunctions,
 476                                                                                           node->hashfunctions,
 477                                                                                           nbuckets,
 478                                                                                           sizeof(TupleHashEntryData),
 479                                                                                           node->tablecxt,
 480                                                                                           tempcxt);
 481         }
 482
 483         /*
 484          * We are probably in a short-lived expression-evaluation context. Switch
 485          * to the child plan's per-query context for calling ExecProcNode.
 486          */
 487         oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
 488
 489         /*
 490          * Reset subplan to start.
 491          */
 492         ExecReScan(planstate, NULL);
 493
 494         /*
 495          * Scan the subplan and load the hash table(s).  Note that when there are
 496          * duplicate rows coming out of the sub-select, only one copy is stored.
 497          */
 498         for (slot = ExecProcNode(planstate);
 499                  !TupIsNull(slot);
 500                  slot = ExecProcNode(planstate))
 501         {
 502                 int                     col = 1;
 503                 ListCell   *plst;
 504                 bool            isnew;
 505
 506                 /*
 507                  * Load up the Params representing the raw sub-select outputs, then
 508                  * form the projection tuple to store in the hashtable.
 509                  */
 510                 foreach(plst, subplan->paramIds)
 511                 {
 512                         int                     paramid = lfirst_int(plst);
 513                         ParamExecData *prmdata;
 514
 515                         prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
 516                         Assert(prmdata->execPlan == NULL);
 517                         prmdata->value = slot_getattr(slot, col,
 518                                                                                   &(prmdata->isnull));
 519                         col++;
 520                 }
 521                 slot = ExecProject(node->projRight, NULL);
 522
 523                 /*
 524                  * If result contains any nulls, store separately or not at all.
 525                  */
 526                 if (slotNoNulls(slot))
 527                 {
 528                         (void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
 529                         node->havehashrows = true;
 530                 }
 531                 else if (node->hashnulls)
 532                 {
 533                         (void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
 534                         node->havenullrows = true;
 535                 }
 536
 537                 /*
 538                  * Reset innerecontext after each inner tuple to free any memory used
 539                  * in hash computation or comparison routines.
 540                  */
 541                 ResetExprContext(innerecontext);
 542         }
 543
 544         /*
 545          * Since the projected tuples are in the sub-query's context and not the
 546          * main context, we'd better clear the tuple slot before there's any
 547          * chance of a reset of the sub-query's context.  Else we will have the
 548          * potential for a double free attempt.  (XXX possibly no longer needed,
 549          * but can't hurt.)
 550          */
 551         ExecClearTuple(node->projRight->pi_slot);
 552
 553         MemoryContextSwitchTo(oldcontext);
 554 }
 555
 556 /*
 557  * findPartialMatch: does the hashtable contain an entry that is not
 558  * provably distinct from the tuple?
 559  *
 560  * We have to scan the whole hashtable; we can't usefully use hashkeys
 561  * to guide probing, since we might get partial matches on tuples with
 562  * hashkeys quite unrelated to what we'd get from the given tuple.
 563  */
 564 static bool
 565 findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot)
 566 {
 567         int                     numCols = hashtable->numCols;
 568         AttrNumber *keyColIdx = hashtable->keyColIdx;
 569         TupleHashIterator hashiter;
 570         TupleHashEntry entry;
 571
 572         ResetTupleHashIterator(hashtable, &hashiter);
 573         while ((entry = ScanTupleHashTable(&hashiter)) != NULL)
 574         {
 575                 ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
 576                 if (!execTuplesUnequal(hashtable->tableslot, slot,
 577                                                            numCols, keyColIdx,
 578                                                            hashtable->eqfunctions,
 579                                                            hashtable->tempcxt))
 580                         return true;
 581         }
 582         return false;
 583 }
 584
 585 /*
 586  * slotAllNulls: is the slot completely NULL?
 587  *
 588  * This does not test for dropped columns, which is OK because we only
 589  * use it on projected tuples.
 590  */
 591 static bool
 592 slotAllNulls(TupleTableSlot *slot)
 593 {
 594         int                     ncols = slot->tts_tupleDescriptor->natts;
 595         int                     i;
 596
 597         for (i = 1; i <= ncols; i++)
 598         {
 599                 if (!slot_attisnull(slot, i))
 600                         return false;
 601         }
 602         return true;
 603 }
 604
 605 /*
 606  * slotNoNulls: is the slot entirely not NULL?
 607  *
 608  * This does not test for dropped columns, which is OK because we only
 609  * use it on projected tuples.
 610  */
 611 static bool
 612 slotNoNulls(TupleTableSlot *slot)
 613 {
 614         int                     ncols = slot->tts_tupleDescriptor->natts;
 615         int                     i;
 616
 617         for (i = 1; i <= ncols; i++)
 618         {
 619                 if (slot_attisnull(slot, i))
 620                         return false;
 621         }
 622         return true;
 623 }
 624
 625 /* ----------------------------------------------------------------
 626  *              ExecInitSubPlan
 627  *
 628  * Note: the eflags are those passed to the parent plan node of this
 629  * subplan; they don't directly describe the execution conditions the
 630  * subplan will face.
 631  * ----------------------------------------------------------------
 632  */
 633 void
 634 ExecInitSubPlan(SubPlanState *node, EState *estate, int eflags)
 635 {
 636         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
 637         EState     *sp_estate;
 638         MemoryContext oldcontext;
 639
 640         /*
 641          * Do access checking on the rangetable entries in the subquery.
 642          */
 643         ExecCheckRTPerms(subplan->rtable);
 644
 645         /*
 646          * initialize my state
 647          */
 648         node->needShutdown = false;
 649         node->curTuple = NULL;
 650         node->projLeft = NULL;
 651         node->projRight = NULL;
 652         node->hashtable = NULL;
 653         node->hashnulls = NULL;
 654         node->tablecxt = NULL;
 655         node->innerecontext = NULL;
 656         node->keyColIdx = NULL;
 657         node->eqfunctions = NULL;
 658         node->hashfunctions = NULL;
 659
 660         /*
 661          * create an EState for the subplan
 662          *
 663          * The subquery needs its own EState because it has its own rangetable. It
 664          * shares our Param ID space, however.  XXX if rangetable access were done
 665          * differently, the subquery could share our EState, which would eliminate
 666          * some thrashing about in this module...
 667          */
 668         sp_estate = CreateExecutorState();
 669         node->sub_estate = sp_estate;
 670
 671         oldcontext = MemoryContextSwitchTo(sp_estate->es_query_cxt);
 672
 673         sp_estate->es_range_table = subplan->rtable;
 674         sp_estate->es_param_list_info = estate->es_param_list_info;
 675         sp_estate->es_param_exec_vals = estate->es_param_exec_vals;
 676         sp_estate->es_tupleTable =
 677                 ExecCreateTupleTable(ExecCountSlotsNode(subplan->plan) + 10);
 678         sp_estate->es_snapshot = estate->es_snapshot;
 679         sp_estate->es_crosscheck_snapshot = estate->es_crosscheck_snapshot;
 680         sp_estate->es_instrument = estate->es_instrument;
 681
 682         /*
 683          * Start up the subplan (this is a very cut-down form of InitPlan())
 684          *
 685          * The subplan will never need to do BACKWARD scan or MARK/RESTORE.
 686          * If it is a parameterless subplan (not initplan), we suggest that it
 687          * be prepared to handle REWIND efficiently; otherwise there is no need.
 688          */
 689         eflags &= EXEC_FLAG_EXPLAIN_ONLY;
 690         if (subplan->parParam == NIL && subplan->setParam == NIL)
 691                 eflags |= EXEC_FLAG_REWIND;
 692
 693         node->planstate = ExecInitNode(subplan->plan, sp_estate, eflags);
 694
 695         node->needShutdown = true;      /* now we need to shutdown the subplan */
 696
 697         MemoryContextSwitchTo(oldcontext);
 698
 699         /*
 700          * If this plan is un-correlated or undirect correlated one and want to
 701          * set params for parent plan then mark parameters as needing evaluation.
 702          *
 703          * Note that in the case of un-correlated subqueries we don't care about
 704          * setting parent->chgParam here: indices take care about it, for others -
 705          * it doesn't matter...
 706          */
 707         if (subplan->setParam != NIL)
 708         {
 709                 ListCell   *lst;
 710
 711                 foreach(lst, subplan->setParam)
 712                 {
 713                         int                     paramid = lfirst_int(lst);
 714                         ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
 715
 716                         prm->execPlan = node;
 717                 }
 718         }
 719
 720         /*
 721          * If we are going to hash the subquery output, initialize relevant stuff.
 722          * (We don't create the hashtable until needed, though.)
 723          */
 724         if (subplan->useHashTable)
 725         {
 726                 int                     ncols,
 727                                         i;
 728                 TupleDesc       tupDesc;
 729                 TupleTable      tupTable;
 730                 TupleTableSlot *slot;
 731                 List       *oplist,
 732                                    *lefttlist,
 733                                    *righttlist,
 734                                    *leftptlist,
 735                                    *rightptlist;
 736                 ListCell   *l;
 737
 738                 /* We need a memory context to hold the hash table(s) */
 739                 node->tablecxt =
 740                         AllocSetContextCreate(CurrentMemoryContext,
 741                                                                   "Subplan HashTable Context",
 742                                                                   ALLOCSET_DEFAULT_MINSIZE,
 743                                                                   ALLOCSET_DEFAULT_INITSIZE,
 744                                                                   ALLOCSET_DEFAULT_MAXSIZE);
 745                 /* and a short-lived exprcontext for function evaluation */
 746                 node->innerecontext = CreateExprContext(estate);
 747                 /* Silly little array of column numbers 1..n */
 748                 ncols = list_length(subplan->paramIds);
 749                 node->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
 750                 for (i = 0; i < ncols; i++)
 751                         node->keyColIdx[i] = i + 1;
 752
 753                 /*
 754                  * We use ExecProject to evaluate the lefthand and righthand
 755                  * expression lists and form tuples.  (You might think that we could
 756                  * use the sub-select's output tuples directly, but that is not the
 757                  * case if we had to insert any run-time coercions of the sub-select's
 758                  * output datatypes; anyway this avoids storing any resjunk columns
 759                  * that might be in the sub-select's output.) Run through the
 760                  * combining expressions to build tlists for the lefthand and
 761                  * righthand sides.  We need both the ExprState list (for ExecProject)
 762                  * and the underlying parse Exprs (for ExecTypeFromTL).
 763                  *
 764                  * We also extract the combining operators themselves to initialize
 765                  * the equality and hashing functions for the hash tables.
 766                  */
 767                 if (IsA(node->testexpr->expr, OpExpr))
 768                 {
 769                         /* single combining operator */
 770                         oplist = list_make1(node->testexpr);
 771                 }
 772                 else if (and_clause((Node *) node->testexpr->expr))
 773                 {
 774                         /* multiple combining operators */
 775                         Assert(IsA(node->testexpr, BoolExprState));
 776                         oplist = ((BoolExprState *) node->testexpr)->args;
 777                 }
 778                 else
 779                 {
 780                         /* shouldn't see anything else in a hashable subplan */
 781                         elog(ERROR, "unrecognized testexpr type: %d",
 782                                  (int) nodeTag(node->testexpr->expr));
 783                         oplist = NIL;           /* keep compiler quiet */
 784                 }
 785                 Assert(list_length(oplist) == ncols);
 786
 787                 lefttlist = righttlist = NIL;
 788                 leftptlist = rightptlist = NIL;
 789                 node->eqfunctions = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 790                 node->hashfunctions = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 791                 i = 1;
 792                 foreach(l, oplist)
 793                 {
 794                         FuncExprState *fstate = (FuncExprState *) lfirst(l);
 795                         OpExpr     *opexpr = (OpExpr *) fstate->xprstate.expr;
 796                         ExprState  *exstate;
 797                         Expr       *expr;
 798                         TargetEntry *tle;
 799                         GenericExprState *tlestate;
 800                         Oid                     hashfn;
 801
 802                         Assert(IsA(fstate, FuncExprState));
 803                         Assert(IsA(opexpr, OpExpr));
 804                         Assert(list_length(fstate->args) == 2);
 805
 806                         /* Process lefthand argument */
 807                         exstate = (ExprState *) linitial(fstate->args);
 808                         expr = exstate->expr;
 809                         tle = makeTargetEntry(expr,
 810                                                                   i,
 811                                                                   NULL,
 812                                                                   false);
 813                         tlestate = makeNode(GenericExprState);
 814                         tlestate->xprstate.expr = (Expr *) tle;
 815                         tlestate->xprstate.evalfunc = NULL;
 816                         tlestate->arg = exstate;
 817                         lefttlist = lappend(lefttlist, tlestate);
 818                         leftptlist = lappend(leftptlist, tle);
 819
 820                         /* Process righthand argument */
 821                         exstate = (ExprState *) lsecond(fstate->args);
 822                         expr = exstate->expr;
 823                         tle = makeTargetEntry(expr,
 824                                                                   i,
 825                                                                   NULL,
 826                                                                   false);
 827                         tlestate = makeNode(GenericExprState);
 828                         tlestate->xprstate.expr = (Expr *) tle;
 829                         tlestate->xprstate.evalfunc = NULL;
 830                         tlestate->arg = exstate;
 831                         righttlist = lappend(righttlist, tlestate);
 832                         rightptlist = lappend(rightptlist, tle);
 833
 834                         /* Lookup the combining function */
 835                         fmgr_info(opexpr->opfuncid, &node->eqfunctions[i - 1]);
 836                         node->eqfunctions[i - 1].fn_expr = (Node *) opexpr;
 837
 838                         /* Lookup the associated hash function */
 839                         hashfn = get_op_hash_function(opexpr->opno);
 840                         if (!OidIsValid(hashfn))
 841                                 elog(ERROR, "could not find hash function for hash operator %u",
 842                                          opexpr->opno);
 843                         fmgr_info(hashfn, &node->hashfunctions[i - 1]);
 844
 845                         i++;
 846                 }
 847
 848                 /*
 849                  * Create a tupletable to hold these tuples.  (Note: we never bother
 850                  * to free the tupletable explicitly; that's okay because it will
 851                  * never store raw disk tuples that might have associated buffer pins.
 852                  * The only resource involved is memory, which will be cleaned up by
 853                  * freeing the query context.)
 854                  */
 855                 tupTable = ExecCreateTupleTable(2);
 856
 857                 /*
 858                  * Construct tupdescs, slots and projection nodes for left and right
 859                  * sides.  The lefthand expressions will be evaluated in the parent
 860                  * plan node's exprcontext, which we don't have access to here.
 861                  * Fortunately we can just pass NULL for now and fill it in later
 862                  * (hack alert!).  The righthand expressions will be evaluated in our
 863                  * own innerecontext.
 864                  */
 865                 tupDesc = ExecTypeFromTL(leftptlist, false);
 866                 slot = ExecAllocTableSlot(tupTable);
 867                 ExecSetSlotDescriptor(slot, tupDesc);
 868                 node->projLeft = ExecBuildProjectionInfo(lefttlist,
 869                                                                                                  NULL,
 870                                                                                                  slot);
 871
 872                 tupDesc = ExecTypeFromTL(rightptlist, false);
 873                 slot = ExecAllocTableSlot(tupTable);
 874                 ExecSetSlotDescriptor(slot, tupDesc);
 875                 node->projRight = ExecBuildProjectionInfo(righttlist,
 876                                                                                                   node->innerecontext,
 877                                                                                                   slot);
 878         }
 879 }
 880
 881 /* ----------------------------------------------------------------
 882  *              ExecSetParamPlan
 883  *
 884  *              Executes an InitPlan subplan and sets its output parameters.
 885  *
 886  * This is called from ExecEvalParam() when the value of a PARAM_EXEC
 887  * parameter is requested and the param's execPlan field is set (indicating
 888  * that the param has not yet been evaluated).  This allows lazy evaluation
 889  * of initplans: we don't run the subplan until/unless we need its output.
 890  * Note that this routine MUST clear the execPlan fields of the plan's
 891  * output parameters after evaluating them!
 892  * ----------------------------------------------------------------
 893  */
 894 void
 895 ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
 896 {
 897         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
 898         PlanState  *planstate = node->planstate;
 899         SubLinkType subLinkType = subplan->subLinkType;
 900         MemoryContext oldcontext;
 901         TupleTableSlot *slot;
 902         ListCell   *l;
 903         bool            found = false;
 904         ArrayBuildState *astate = NULL;
 905
 906         /*
 907          * Must switch to child query's per-query memory context.
 908          */
 909         oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
 910
 911         if (subLinkType == ANY_SUBLINK ||
 912                 subLinkType == ALL_SUBLINK)
 913                 elog(ERROR, "ANY/ALL subselect unsupported as initplan");
 914
 915         if (planstate->chgParam != NULL)
 916                 ExecReScan(planstate, NULL);
 917
 918         for (slot = ExecProcNode(planstate);
 919                  !TupIsNull(slot);
 920                  slot = ExecProcNode(planstate))
 921         {
 922                 TupleDesc       tdesc = slot->tts_tupleDescriptor;
 923                 int                     i = 1;
 924
 925                 if (subLinkType == EXISTS_SUBLINK)
 926                 {
 927                         /* There can be only one param... */
 928                         int                     paramid = linitial_int(subplan->setParam);
 929                         ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 930
 931                         prm->execPlan = NULL;
 932                         prm->value = BoolGetDatum(true);
 933                         prm->isnull = false;
 934                         found = true;
 935                         break;
 936                 }
 937
 938                 if (subLinkType == ARRAY_SUBLINK)
 939                 {
 940                         Datum           dvalue;
 941                         bool            disnull;
 942
 943                         found = true;
 944                         /* stash away current value */
 945                         dvalue = slot_getattr(slot, 1, &disnull);
 946                         astate = accumArrayResult(astate, dvalue, disnull,
 947                                                                           tdesc->attrs[0]->atttypid,
 948                                                                           oldcontext);
 949                         /* keep scanning subplan to collect all values */
 950                         continue;
 951                 }
 952
 953                 if (found &&
 954                         (subLinkType == EXPR_SUBLINK ||
 955                          subLinkType == ROWCOMPARE_SUBLINK))
 956                         ereport(ERROR,
 957                                         (errcode(ERRCODE_CARDINALITY_VIOLATION),
 958                                          errmsg("more than one row returned by a subquery used as an expression")));
 959
 960                 found = true;
 961
 962                 /*
 963                  * We need to copy the subplan's tuple into our own context, in case
 964                  * any of the params are pass-by-ref type --- the pointers stored in
 965                  * the param structs will point at this copied tuple! node->curTuple
 966                  * keeps track of the copied tuple for eventual freeing.
 967                  */
 968                 MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
 969                 if (node->curTuple)
 970                         heap_freetuple(node->curTuple);
 971                 node->curTuple = ExecCopySlotTuple(slot);
 972                 MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
 973
 974                 /*
 975                  * Now set all the setParam params from the columns of the tuple
 976                  */
 977                 foreach(l, subplan->setParam)
 978                 {
 979                         int                     paramid = lfirst_int(l);
 980                         ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 981
 982                         prm->execPlan = NULL;
 983                         prm->value = heap_getattr(node->curTuple, i, tdesc,
 984                                                                           &(prm->isnull));
 985                         i++;
 986                 }
 987         }
 988
 989         if (!found)
 990         {
 991                 if (subLinkType == EXISTS_SUBLINK)
 992                 {
 993                         /* There can be only one param... */
 994                         int                     paramid = linitial_int(subplan->setParam);
 995                         ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 996
 997                         prm->execPlan = NULL;
 998                         prm->value = BoolGetDatum(false);
 999                         prm->isnull = false;
1000                 }
1001                 else
1002                 {
1003                         foreach(l, subplan->setParam)
1004                         {
1005                                 int                     paramid = lfirst_int(l);
1006                                 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1007
1008                                 prm->execPlan = NULL;
1009                                 prm->value = (Datum) 0;
1010                                 prm->isnull = true;
1011                         }
1012                 }
1013         }
1014         else if (subLinkType == ARRAY_SUBLINK)
1015         {
1016                 /* There can be only one param... */
1017                 int                     paramid = linitial_int(subplan->setParam);
1018                 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1019
1020                 Assert(astate != NULL);
1021                 prm->execPlan = NULL;
1022                 /* We build the result in query context so it won't disappear */
1023                 prm->value = makeArrayResult(astate, econtext->ecxt_per_query_memory);
1024                 prm->isnull = false;
1025         }
1026
1027         MemoryContextSwitchTo(oldcontext);
1028 }
1029
1030 /* ----------------------------------------------------------------
1031  *              ExecEndSubPlan
1032  * ----------------------------------------------------------------
1033  */
1034 void
1035 ExecEndSubPlan(SubPlanState *node)
1036 {
1037         if (node->needShutdown)
1038         {
1039                 MemoryContext oldcontext;
1040
1041                 oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
1042                 ExecEndPlan(node->planstate, node->sub_estate);
1043                 MemoryContextSwitchTo(oldcontext);
1044                 FreeExecutorState(node->sub_estate);
1045                 node->sub_estate = NULL;
1046                 node->planstate = NULL;
1047                 node->needShutdown = false;
1048         }
1049 }
1050
1051 /*
1052  * Mark an initplan as needing recalculation
1053  */
1054 void
1055 ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
1056 {
1057         PlanState  *planstate = node->planstate;
1058         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
1059         EState     *estate = parent->state;
1060         ListCell   *l;
1061
1062         /* sanity checks */
1063         if (subplan->parParam != NIL)
1064                 elog(ERROR, "direct correlated subquery unsupported as initplan");
1065         if (subplan->setParam == NIL)
1066                 elog(ERROR, "setParam list of initplan is empty");
1067         if (bms_is_empty(planstate->plan->extParam))
1068                 elog(ERROR, "extParam set of initplan is empty");
1069
1070         /*
1071          * Don't actually re-scan: ExecSetParamPlan does it if needed.
1072          */
1073
1074         /*
1075          * Mark this subplan's output parameters as needing recalculation
1076          */
1077         foreach(l, subplan->setParam)
1078         {
1079                 int                     paramid = lfirst_int(l);
1080                 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
1081
1082                 prm->execPlan = node;
1083                 parent->chgParam = bms_add_member(parent->chgParam, paramid);
1084         }
1085 }