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) 1996-2007, 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 1.88 2007/04/26 23:24:44 tgl Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 /*
  15  *       INTERFACE ROUTINES
  16  *              ExecSubPlan  - process a subselect
  17  *              ExecInitSubPlan - initialize a subselect
  18  */
  19 #include "postgres.h"
  20
  21 #include <math.h>
  22
  23 #include "access/heapam.h"
  24 #include "executor/executor.h"
  25 #include "executor/nodeSubplan.h"
  26 #include "nodes/makefuncs.h"
  27 #include "optimizer/clauses.h"
  28 #include "utils/array.h"
  29 #include "utils/lsyscache.h"
  30 #include "utils/memutils.h"
  31
  32
  33 static Datum ExecHashSubPlan(SubPlanState *node,
  34                                 ExprContext *econtext,
  35                                 bool *isNull);
  36 static Datum ExecScanSubPlan(SubPlanState *node,
  37                                 ExprContext *econtext,
  38                                 bool *isNull);
  39 static void buildSubPlanHash(SubPlanState *node, ExprContext *econtext);
  40 static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot);
  41 static bool slotAllNulls(TupleTableSlot *slot);
  42 static bool slotNoNulls(TupleTableSlot *slot);
  43
  44
  45 /* ----------------------------------------------------------------
  46  *              ExecSubPlan
  47  * ----------------------------------------------------------------
  48  */
  49 Datum
  50 ExecSubPlan(SubPlanState *node,
  51                         ExprContext *econtext,
  52                         bool *isNull,
  53                         ExprDoneCond *isDone)
  54 {
  55         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
  56
  57         /* Set default values for result flags: non-null, not a set result */
  58         *isNull = false;
  59         if (isDone)
  60                 *isDone = ExprSingleResult;
  61
  62         if (subplan->setParam != NIL)
  63                 elog(ERROR, "cannot set parent params from subquery");
  64
  65         if (subplan->useHashTable)
  66                 return ExecHashSubPlan(node, econtext, isNull);
  67         else
  68                 return ExecScanSubPlan(node, econtext, isNull);
  69 }
  70
  71 /*
  72  * ExecHashSubPlan: store subselect result in an in-memory hash table
  73  */
  74 static Datum
  75 ExecHashSubPlan(SubPlanState *node,
  76                                 ExprContext *econtext,
  77                                 bool *isNull)
  78 {
  79         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
  80         PlanState  *planstate = node->planstate;
  81         ExprContext *innerecontext = node->innerecontext;
  82         TupleTableSlot *slot;
  83
  84         /* Shouldn't have any direct correlation Vars */
  85         if (subplan->parParam != NIL || node->args != NIL)
  86                 elog(ERROR, "hashed subplan with direct correlation not supported");
  87
  88         /*
  89          * If first time through or we need to rescan the subplan, build the hash
  90          * table.
  91          */
  92         if (node->hashtable == NULL || planstate->chgParam != NULL)
  93                 buildSubPlanHash(node, econtext);
  94
  95         /*
  96          * The result for an empty subplan is always FALSE; no need to evaluate
  97          * lefthand side.
  98          */
  99         *isNull = false;
 100         if (!node->havehashrows && !node->havenullrows)
 101                 return BoolGetDatum(false);
 102
 103         /*
 104          * Evaluate lefthand expressions and form a projection tuple. First we
 105          * have to set the econtext to use (hack alert!).
 106          */
 107         node->projLeft->pi_exprContext = econtext;
 108         slot = ExecProject(node->projLeft, NULL);
 109
 110         /*
 111          * Note: because we are typically called in a per-tuple context, we have
 112          * to explicitly clear the projected tuple before returning. Otherwise,
 113          * we'll have a double-free situation: the per-tuple context will probably
 114          * be reset before we're called again, and then the tuple slot will think
 115          * it still needs to free the tuple.
 116          */
 117
 118         /*
 119          * Since the hashtable routines will use innerecontext's per-tuple memory
 120          * as working memory, be sure to reset it for each tuple.
 121          */
 122         ResetExprContext(innerecontext);
 123
 124         /*
 125          * If the LHS is all non-null, probe for an exact match in the main hash
 126          * table.  If we find one, the result is TRUE. Otherwise, scan the
 127          * partly-null table to see if there are any rows that aren't provably
 128          * unequal to the LHS; if so, the result is UNKNOWN.  (We skip that part
 129          * if we don't care about UNKNOWN.) Otherwise, the result is FALSE.
 130          *
 131          * Note: the reason we can avoid a full scan of the main hash table is
 132          * that the combining operators are assumed never to yield NULL when both
 133          * inputs are non-null.  If they were to do so, we might need to produce
 134          * UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the
 135          * LHS to some main-table entry --- which is a comparison we will not even
 136          * make, unless there's a chance match of hash keys.
 137          */
 138         if (slotNoNulls(slot))
 139         {
 140                 if (node->havehashrows &&
 141                         FindTupleHashEntry(node->hashtable,
 142                                                            slot,
 143                                                            node->cur_eq_funcs,
 144                                                            node->lhs_hash_funcs) != NULL)
 145                 {
 146                         ExecClearTuple(slot);
 147                         return BoolGetDatum(true);
 148                 }
 149                 if (node->havenullrows &&
 150                         findPartialMatch(node->hashnulls, slot))
 151                 {
 152                         ExecClearTuple(slot);
 153                         *isNull = true;
 154                         return BoolGetDatum(false);
 155                 }
 156                 ExecClearTuple(slot);
 157                 return BoolGetDatum(false);
 158         }
 159
 160         /*
 161          * When the LHS is partly or wholly NULL, we can never return TRUE. If we
 162          * don't care about UNKNOWN, just return FALSE.  Otherwise, if the LHS is
 163          * wholly NULL, immediately return UNKNOWN.  (Since the combining
 164          * operators are strict, the result could only be FALSE if the sub-select
 165          * were empty, but we already handled that case.) Otherwise, we must scan
 166          * both the main and partly-null tables to see if there are any rows that
 167          * aren't provably unequal to the LHS; if so, the result is UNKNOWN.
 168          * Otherwise, the result is FALSE.
 169          */
 170         if (node->hashnulls == NULL)
 171         {
 172                 ExecClearTuple(slot);
 173                 return BoolGetDatum(false);
 174         }
 175         if (slotAllNulls(slot))
 176         {
 177                 ExecClearTuple(slot);
 178                 *isNull = true;
 179                 return BoolGetDatum(false);
 180         }
 181         /* Scan partly-null table first, since more likely to get a match */
 182         if (node->havenullrows &&
 183                 findPartialMatch(node->hashnulls, slot))
 184         {
 185                 ExecClearTuple(slot);
 186                 *isNull = true;
 187                 return BoolGetDatum(false);
 188         }
 189         if (node->havehashrows &&
 190                 findPartialMatch(node->hashtable, slot))
 191         {
 192                 ExecClearTuple(slot);
 193                 *isNull = true;
 194                 return BoolGetDatum(false);
 195         }
 196         ExecClearTuple(slot);
 197         return BoolGetDatum(false);
 198 }
 199
 200 /*
 201  * ExecScanSubPlan: default case where we have to rescan subplan each time
 202  */
 203 static Datum
 204 ExecScanSubPlan(SubPlanState *node,
 205                                 ExprContext *econtext,
 206                                 bool *isNull)
 207 {
 208         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
 209         PlanState  *planstate = node->planstate;
 210         SubLinkType subLinkType = subplan->subLinkType;
 211         MemoryContext oldcontext;
 212         TupleTableSlot *slot;
 213         Datum           result;
 214         bool            found = false;  /* TRUE if got at least one subplan tuple */
 215         ListCell   *pvar;
 216         ListCell   *l;
 217         ArrayBuildState *astate = NULL;
 218
 219         /*
 220          * We are probably in a short-lived expression-evaluation context. Switch
 221          * to the per-query context for manipulating the child plan's chgParam,
 222          * calling ExecProcNode on it, etc.
 223          */
 224         oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
 225
 226         /*
 227          * Set Params of this plan from parent plan correlation values. (Any
 228          * calculation we have to do is done in the parent econtext, since the
 229          * Param values don't need to have per-query lifetime.)
 230          */
 231         Assert(list_length(subplan->parParam) == list_length(node->args));
 232
 233         forboth(l, subplan->parParam, pvar, node->args)
 234         {
 235                 int                     paramid = lfirst_int(l);
 236                 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 237
 238                 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
 239                                                                                            econtext,
 240                                                                                            &(prm->isnull),
 241                                                                                            NULL);
 242                 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
 243         }
 244
 245         ExecReScan(planstate, NULL);
 246
 247         /*
 248          * For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result
 249          * is boolean as are the results of the combining operators. We combine
 250          * results across tuples (if the subplan produces more than one) using OR
 251          * semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
 252          * (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.)
 253          * NULL results from the combining operators are handled according to the
 254          * usual SQL semantics for OR and AND.  The result for no input tuples is
 255          * FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
 256          * ROWCOMPARE_SUBLINK.
 257          *
 258          * For EXPR_SUBLINK we require the subplan to produce no more than one
 259          * tuple, else an error is raised. For ARRAY_SUBLINK we allow the subplan
 260          * to produce more than one tuple. In either case, if zero tuples are
 261          * produced, we return NULL. Assuming we get a tuple, we just use its
 262          * first column (there can be only one non-junk column in this case).
 263          */
 264         result = BoolGetDatum(subLinkType == ALL_SUBLINK);
 265         *isNull = false;
 266
 267         for (slot = ExecProcNode(planstate);
 268                  !TupIsNull(slot);
 269                  slot = ExecProcNode(planstate))
 270         {
 271                 TupleDesc       tdesc = slot->tts_tupleDescriptor;
 272                 Datum           rowresult;
 273                 bool            rownull;
 274                 int                     col;
 275                 ListCell   *plst;
 276
 277                 if (subLinkType == EXISTS_SUBLINK)
 278                 {
 279                         found = true;
 280                         result = BoolGetDatum(true);
 281                         break;
 282                 }
 283
 284                 if (subLinkType == EXPR_SUBLINK)
 285                 {
 286                         /* cannot allow multiple input tuples for EXPR sublink */
 287                         if (found)
 288                                 ereport(ERROR,
 289                                                 (errcode(ERRCODE_CARDINALITY_VIOLATION),
 290                                                  errmsg("more than one row returned by a subquery used as an expression")));
 291                         found = true;
 292
 293                         /*
 294                          * We need to copy the subplan's tuple in case the result is of
 295                          * pass-by-ref type --- our return value will point into this
 296                          * copied tuple!  Can't use the subplan's instance of the tuple
 297                          * since it won't still be valid after next ExecProcNode() call.
 298                          * node->curTuple keeps track of the copied tuple for eventual
 299                          * freeing.
 300                          */
 301                         if (node->curTuple)
 302                                 heap_freetuple(node->curTuple);
 303                         node->curTuple = ExecCopySlotTuple(slot);
 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 the
 336                  * 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, ExprContext *econtext)
 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. We
 438          * 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->tab_eq_funcs,
 457                                                                                   node->tab_hash_funcs,
 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->tab_eq_funcs,
 476                                                                                           node->tab_hash_funcs,
 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 per-query context for manipulating the child plan.
 486          */
 487         oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
 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         InitTupleHashIterator(hashtable, &hashiter);
 573         while ((entry = ScanTupleHashTable(&hashiter)) != NULL)
 574         {
 575                 ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
 576                 if (!execTuplesUnequal(slot, hashtable->tableslot,
 577                                                            numCols, keyColIdx,
 578                                                            hashtable->cur_eq_funcs,
 579                                                            hashtable->tempcxt))
 580                 {
 581                         TermTupleHashIterator(&hashiter);
 582                         return true;
 583                 }
 584         }
 585         /* No TermTupleHashIterator call needed here */
 586         return false;
 587 }
 588
 589 /*
 590  * slotAllNulls: is the slot completely NULL?
 591  *
 592  * This does not test for dropped columns, which is OK because we only
 593  * use it on projected tuples.
 594  */
 595 static bool
 596 slotAllNulls(TupleTableSlot *slot)
 597 {
 598         int                     ncols = slot->tts_tupleDescriptor->natts;
 599         int                     i;
 600
 601         for (i = 1; i <= ncols; i++)
 602         {
 603                 if (!slot_attisnull(slot, i))
 604                         return false;
 605         }
 606         return true;
 607 }
 608
 609 /*
 610  * slotNoNulls: is the slot entirely not NULL?
 611  *
 612  * This does not test for dropped columns, which is OK because we only
 613  * use it on projected tuples.
 614  */
 615 static bool
 616 slotNoNulls(TupleTableSlot *slot)
 617 {
 618         int                     ncols = slot->tts_tupleDescriptor->natts;
 619         int                     i;
 620
 621         for (i = 1; i <= ncols; i++)
 622         {
 623                 if (slot_attisnull(slot, i))
 624                         return false;
 625         }
 626         return true;
 627 }
 628
 629 /* ----------------------------------------------------------------
 630  *              ExecInitSubPlan
 631  *
 632  * Create a SubPlanState for a SubPlan; this is the SubPlan-specific part
 633  * of ExecInitExpr().  We split it out so that it can be used for InitPlans
 634  * as well as regular SubPlans.  Note that we don't link the SubPlan into
 635  * the parent's subPlan list, because that shouldn't happen for InitPlans.
 636  * Instead, ExecInitExpr() does that one part.
 637  * ----------------------------------------------------------------
 638  */
 639 SubPlanState *
 640 ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 641 {
 642         SubPlanState *sstate = makeNode(SubPlanState);
 643         EState     *estate = parent->state;
 644
 645         sstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecSubPlan;
 646         sstate->xprstate.expr = (Expr *) subplan;
 647
 648         /* Link the SubPlanState to already-initialized subplan */
 649         sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates,
 650                                                                                            subplan->plan_id - 1);
 651
 652         /* Initialize subexpressions */
 653         sstate->testexpr = ExecInitExpr((Expr *) subplan->testexpr, parent);
 654         sstate->args = (List *) ExecInitExpr((Expr *) subplan->args, parent);
 655
 656         /*
 657          * initialize my state
 658          */
 659         sstate->curTuple = NULL;
 660         sstate->projLeft = NULL;
 661         sstate->projRight = NULL;
 662         sstate->hashtable = NULL;
 663         sstate->hashnulls = NULL;
 664         sstate->tablecxt = NULL;
 665         sstate->innerecontext = NULL;
 666         sstate->keyColIdx = NULL;
 667         sstate->tab_hash_funcs = NULL;
 668         sstate->tab_eq_funcs = NULL;
 669         sstate->lhs_hash_funcs = NULL;
 670         sstate->cur_eq_funcs = NULL;
 671
 672         /*
 673          * If this plan is un-correlated or undirect correlated one and want to
 674          * set params for parent plan then mark parameters as needing evaluation.
 675          *
 676          * Note that in the case of un-correlated subqueries we don't care about
 677          * setting parent->chgParam here: indices take care about it, for others -
 678          * it doesn't matter...
 679          */
 680         if (subplan->setParam != NIL)
 681         {
 682                 ListCell   *lst;
 683
 684                 foreach(lst, subplan->setParam)
 685                 {
 686                         int                     paramid = lfirst_int(lst);
 687                         ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
 688
 689                         prm->execPlan = sstate;
 690                 }
 691         }
 692
 693         /*
 694          * If we are going to hash the subquery output, initialize relevant stuff.
 695          * (We don't create the hashtable until needed, though.)
 696          */
 697         if (subplan->useHashTable)
 698         {
 699                 int                     ncols,
 700                                         i;
 701                 TupleDesc       tupDesc;
 702                 TupleTable      tupTable;
 703                 TupleTableSlot *slot;
 704                 List       *oplist,
 705                                    *lefttlist,
 706                                    *righttlist,
 707                                    *leftptlist,
 708                                    *rightptlist;
 709                 ListCell   *l;
 710
 711                 /* We need a memory context to hold the hash table(s) */
 712                 sstate->tablecxt =
 713                         AllocSetContextCreate(CurrentMemoryContext,
 714                                                                   "Subplan HashTable Context",
 715                                                                   ALLOCSET_DEFAULT_MINSIZE,
 716                                                                   ALLOCSET_DEFAULT_INITSIZE,
 717                                                                   ALLOCSET_DEFAULT_MAXSIZE);
 718                 /* and a short-lived exprcontext for function evaluation */
 719                 sstate->innerecontext = CreateExprContext(estate);
 720                 /* Silly little array of column numbers 1..n */
 721                 ncols = list_length(subplan->paramIds);
 722                 sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
 723                 for (i = 0; i < ncols; i++)
 724                         sstate->keyColIdx[i] = i + 1;
 725
 726                 /*
 727                  * We use ExecProject to evaluate the lefthand and righthand
 728                  * expression lists and form tuples.  (You might think that we could
 729                  * use the sub-select's output tuples directly, but that is not the
 730                  * case if we had to insert any run-time coercions of the sub-select's
 731                  * output datatypes; anyway this avoids storing any resjunk columns
 732                  * that might be in the sub-select's output.) Run through the
 733                  * combining expressions to build tlists for the lefthand and
 734                  * righthand sides.  We need both the ExprState list (for ExecProject)
 735                  * and the underlying parse Exprs (for ExecTypeFromTL).
 736                  *
 737                  * We also extract the combining operators themselves to initialize
 738                  * the equality and hashing functions for the hash tables.
 739                  */
 740                 if (IsA(sstate->testexpr->expr, OpExpr))
 741                 {
 742                         /* single combining operator */
 743                         oplist = list_make1(sstate->testexpr);
 744                 }
 745                 else if (and_clause((Node *) sstate->testexpr->expr))
 746                 {
 747                         /* multiple combining operators */
 748                         Assert(IsA(sstate->testexpr, BoolExprState));
 749                         oplist = ((BoolExprState *) sstate->testexpr)->args;
 750                 }
 751                 else
 752                 {
 753                         /* shouldn't see anything else in a hashable subplan */
 754                         elog(ERROR, "unrecognized testexpr type: %d",
 755                                  (int) nodeTag(sstate->testexpr->expr));
 756                         oplist = NIL;           /* keep compiler quiet */
 757                 }
 758                 Assert(list_length(oplist) == ncols);
 759
 760                 lefttlist = righttlist = NIL;
 761                 leftptlist = rightptlist = NIL;
 762                 sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 763                 sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 764                 sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 765                 sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 766                 i = 1;
 767                 foreach(l, oplist)
 768                 {
 769                         FuncExprState *fstate = (FuncExprState *) lfirst(l);
 770                         OpExpr     *opexpr = (OpExpr *) fstate->xprstate.expr;
 771                         ExprState  *exstate;
 772                         Expr       *expr;
 773                         TargetEntry *tle;
 774                         GenericExprState *tlestate;
 775                         Oid                     rhs_eq_oper;
 776                         Oid                     left_hashfn;
 777                         Oid                     right_hashfn;
 778
 779                         Assert(IsA(fstate, FuncExprState));
 780                         Assert(IsA(opexpr, OpExpr));
 781                         Assert(list_length(fstate->args) == 2);
 782
 783                         /* Process lefthand argument */
 784                         exstate = (ExprState *) linitial(fstate->args);
 785                         expr = exstate->expr;
 786                         tle = makeTargetEntry(expr,
 787                                                                   i,
 788                                                                   NULL,
 789                                                                   false);
 790                         tlestate = makeNode(GenericExprState);
 791                         tlestate->xprstate.expr = (Expr *) tle;
 792                         tlestate->xprstate.evalfunc = NULL;
 793                         tlestate->arg = exstate;
 794                         lefttlist = lappend(lefttlist, tlestate);
 795                         leftptlist = lappend(leftptlist, tle);
 796
 797                         /* Process righthand argument */
 798                         exstate = (ExprState *) lsecond(fstate->args);
 799                         expr = exstate->expr;
 800                         tle = makeTargetEntry(expr,
 801                                                                   i,
 802                                                                   NULL,
 803                                                                   false);
 804                         tlestate = makeNode(GenericExprState);
 805                         tlestate->xprstate.expr = (Expr *) tle;
 806                         tlestate->xprstate.evalfunc = NULL;
 807                         tlestate->arg = exstate;
 808                         righttlist = lappend(righttlist, tlestate);
 809                         rightptlist = lappend(rightptlist, tle);
 810
 811                         /* Lookup the equality function (potentially cross-type) */
 812                         fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
 813                         sstate->cur_eq_funcs[i - 1].fn_expr = (Node *) opexpr;
 814
 815                         /* Look up the equality function for the RHS type */
 816                         if (!get_compatible_hash_operators(opexpr->opno,
 817                                                                                            NULL, &rhs_eq_oper))
 818                                 elog(ERROR, "could not find compatible hash operator for operator %u",
 819                                          opexpr->opno);
 820                         fmgr_info(get_opcode(rhs_eq_oper), &sstate->tab_eq_funcs[i - 1]);
 821
 822                         /* Lookup the associated hash functions */
 823                         if (!get_op_hash_functions(opexpr->opno,
 824                                                                            &left_hashfn, &right_hashfn))
 825                                 elog(ERROR, "could not find hash function for hash operator %u",
 826                                          opexpr->opno);
 827                         fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 828                         fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 829
 830                         i++;
 831                 }
 832
 833                 /*
 834                  * Create a tupletable to hold these tuples.  (Note: we never bother
 835                  * to free the tupletable explicitly; that's okay because it will
 836                  * never store raw disk tuples that might have associated buffer pins.
 837                  * The only resource involved is memory, which will be cleaned up by
 838                  * freeing the query context.)
 839                  */
 840                 tupTable = ExecCreateTupleTable(2);
 841
 842                 /*
 843                  * Construct tupdescs, slots and projection nodes for left and right
 844                  * sides.  The lefthand expressions will be evaluated in the parent
 845                  * plan node's exprcontext, which we don't have access to here.
 846                  * Fortunately we can just pass NULL for now and fill it in later
 847                  * (hack alert!).  The righthand expressions will be evaluated in our
 848                  * own innerecontext.
 849                  */
 850                 tupDesc = ExecTypeFromTL(leftptlist, false);
 851                 slot = ExecAllocTableSlot(tupTable);
 852                 ExecSetSlotDescriptor(slot, tupDesc);
 853                 sstate->projLeft = ExecBuildProjectionInfo(lefttlist,
 854                                                                                                  NULL,
 855                                                                                                  slot,
 856                                                                                                  NULL);
 857
 858                 tupDesc = ExecTypeFromTL(rightptlist, false);
 859                 slot = ExecAllocTableSlot(tupTable);
 860                 ExecSetSlotDescriptor(slot, tupDesc);
 861                 sstate->projRight = ExecBuildProjectionInfo(righttlist,
 862                                                                                                   sstate->innerecontext,
 863                                                                                                   slot,
 864                                                                                                   NULL);
 865         }
 866
 867         return sstate;
 868 }
 869
 870 /* ----------------------------------------------------------------
 871  *              ExecSetParamPlan
 872  *
 873  *              Executes an InitPlan subplan and sets its output parameters.
 874  *
 875  * This is called from ExecEvalParam() when the value of a PARAM_EXEC
 876  * parameter is requested and the param's execPlan field is set (indicating
 877  * that the param has not yet been evaluated).  This allows lazy evaluation
 878  * of initplans: we don't run the subplan until/unless we need its output.
 879  * Note that this routine MUST clear the execPlan fields of the plan's
 880  * output parameters after evaluating them!
 881  * ----------------------------------------------------------------
 882  */
 883 void
 884 ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
 885 {
 886         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
 887         PlanState  *planstate = node->planstate;
 888         SubLinkType subLinkType = subplan->subLinkType;
 889         MemoryContext oldcontext;
 890         TupleTableSlot *slot;
 891         ListCell   *l;
 892         bool            found = false;
 893         ArrayBuildState *astate = NULL;
 894
 895         /*
 896          * Must switch to per-query memory context.
 897          */
 898         oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
 899
 900         if (subLinkType == ANY_SUBLINK ||
 901                 subLinkType == ALL_SUBLINK)
 902                 elog(ERROR, "ANY/ALL subselect unsupported as initplan");
 903
 904         if (planstate->chgParam != NULL)
 905                 ExecReScan(planstate, NULL);
 906
 907         for (slot = ExecProcNode(planstate);
 908                  !TupIsNull(slot);
 909                  slot = ExecProcNode(planstate))
 910         {
 911                 TupleDesc       tdesc = slot->tts_tupleDescriptor;
 912                 int                     i = 1;
 913
 914                 if (subLinkType == EXISTS_SUBLINK)
 915                 {
 916                         /* There can be only one param... */
 917                         int                     paramid = linitial_int(subplan->setParam);
 918                         ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 919
 920                         prm->execPlan = NULL;
 921                         prm->value = BoolGetDatum(true);
 922                         prm->isnull = false;
 923                         found = true;
 924                         break;
 925                 }
 926
 927                 if (subLinkType == ARRAY_SUBLINK)
 928                 {
 929                         Datum           dvalue;
 930                         bool            disnull;
 931
 932                         found = true;
 933                         /* stash away current value */
 934                         dvalue = slot_getattr(slot, 1, &disnull);
 935                         astate = accumArrayResult(astate, dvalue, disnull,
 936                                                                           tdesc->attrs[0]->atttypid,
 937                                                                           oldcontext);
 938                         /* keep scanning subplan to collect all values */
 939                         continue;
 940                 }
 941
 942                 if (found &&
 943                         (subLinkType == EXPR_SUBLINK ||
 944                          subLinkType == ROWCOMPARE_SUBLINK))
 945                         ereport(ERROR,
 946                                         (errcode(ERRCODE_CARDINALITY_VIOLATION),
 947                                          errmsg("more than one row returned by a subquery used as an expression")));
 948
 949                 found = true;
 950
 951                 /*
 952                  * We need to copy the subplan's tuple into our own context, in case
 953                  * any of the params are pass-by-ref type --- the pointers stored in
 954                  * the param structs will point at this copied tuple! node->curTuple
 955                  * keeps track of the copied tuple for eventual freeing.
 956                  */
 957                 if (node->curTuple)
 958                         heap_freetuple(node->curTuple);
 959                 node->curTuple = ExecCopySlotTuple(slot);
 960
 961                 /*
 962                  * Now set all the setParam params from the columns of the tuple
 963                  */
 964                 foreach(l, subplan->setParam)
 965                 {
 966                         int                     paramid = lfirst_int(l);
 967                         ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 968
 969                         prm->execPlan = NULL;
 970                         prm->value = heap_getattr(node->curTuple, i, tdesc,
 971                                                                           &(prm->isnull));
 972                         i++;
 973                 }
 974         }
 975
 976         if (!found)
 977         {
 978                 if (subLinkType == EXISTS_SUBLINK)
 979                 {
 980                         /* There can be only one param... */
 981                         int                     paramid = linitial_int(subplan->setParam);
 982                         ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 983
 984                         prm->execPlan = NULL;
 985                         prm->value = BoolGetDatum(false);
 986                         prm->isnull = false;
 987                 }
 988                 else
 989                 {
 990                         foreach(l, subplan->setParam)
 991                         {
 992                                 int                     paramid = lfirst_int(l);
 993                                 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
 994
 995                                 prm->execPlan = NULL;
 996                                 prm->value = (Datum) 0;
 997                                 prm->isnull = true;
 998                         }
 999                 }
1000         }
1001         else if (subLinkType == ARRAY_SUBLINK)
1002         {
1003                 /* There can be only one param... */
1004                 int                     paramid = linitial_int(subplan->setParam);
1005                 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1006
1007                 Assert(astate != NULL);
1008                 prm->execPlan = NULL;
1009                 /* We build the result in query context so it won't disappear */
1010                 prm->value = makeArrayResult(astate, econtext->ecxt_per_query_memory);
1011                 prm->isnull = false;
1012         }
1013
1014         MemoryContextSwitchTo(oldcontext);
1015 }
1016
1017 /*
1018  * Mark an initplan as needing recalculation
1019  */
1020 void
1021 ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
1022 {
1023         PlanState  *planstate = node->planstate;
1024         SubPlan    *subplan = (SubPlan *) node->xprstate.expr;
1025         EState     *estate = parent->state;
1026         ListCell   *l;
1027
1028         /* sanity checks */
1029         if (subplan->parParam != NIL)
1030                 elog(ERROR, "direct correlated subquery unsupported as initplan");
1031         if (subplan->setParam == NIL)
1032                 elog(ERROR, "setParam list of initplan is empty");
1033         if (bms_is_empty(planstate->plan->extParam))
1034                 elog(ERROR, "extParam set of initplan is empty");
1035
1036         /*
1037          * Don't actually re-scan: ExecSetParamPlan does it if needed.
1038          */
1039
1040         /*
1041          * Mark this subplan's output parameters as needing recalculation
1042          */
1043         foreach(l, subplan->setParam)
1044         {
1045                 int                     paramid = lfirst_int(l);
1046                 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
1047
1048                 prm->execPlan = node;
1049                 parent->chgParam = bms_add_member(parent->chgParam, paramid);
1050         }
1051 }