src/backend/executor/execAmi.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * execAmi.c
   4  *        miscellaneous executor access method routines
   5  *
   6  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *      $Id: execAmi.c,v 1.55 2000/11/08 22:09:57 tgl Exp $
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 /*
  14  *       INTERFACE ROUTINES
  15  *
  16  *              ExecOpenScanR   \                                                         / amopen
  17  *              ExecBeginScan    \                                                       /      ambeginscan
  18  *              ExecCloseR                \                                                     /       amclose
  19  *              ExecInsert                 \  executor interface   /    aminsert
  20  *              ExecReScanR                /  to access methods    \    amrescan
  21  *              ExecMarkPos               /                                                     \       ammarkpos
  22  *              ExecRestrPos     /                                                       \  amrestpos
  23  */
  24
  25 #include "postgres.h"
  26
  27
  28 #include "access/genam.h"
  29 #include "access/heapam.h"
  30 #include "catalog/heap.h"
  31 #include "executor/execdebug.h"
  32 #include "executor/nodeAgg.h"
  33 #include "executor/nodeAppend.h"
  34 #include "executor/nodeGroup.h"
  35 #include "executor/nodeGroup.h"
  36 #include "executor/nodeHash.h"
  37 #include "executor/nodeHashjoin.h"
  38 #include "executor/nodeIndexscan.h"
  39 #include "executor/nodeTidscan.h"
  40 #include "executor/nodeLimit.h"
  41 #include "executor/nodeMaterial.h"
  42 #include "executor/nodeMergejoin.h"
  43 #include "executor/nodeNestloop.h"
  44 #include "executor/nodeResult.h"
  45 #include "executor/nodeSeqscan.h"
  46 #include "executor/nodeSetOp.h"
  47 #include "executor/nodeSort.h"
  48 #include "executor/nodeSubplan.h"
  49 #include "executor/nodeSubqueryscan.h"
  50 #include "executor/nodeUnique.h"
  51
  52 static Pointer ExecBeginScan(Relation relation, int nkeys, ScanKey skeys,
  53                           bool isindex, ScanDirection dir, Snapshot snapshot);
  54
  55 /* ----------------------------------------------------------------
  56  *              ExecOpenScanR
  57  *
  58  * old comments:
  59  *              Parameters:
  60  *                relation -- relation to be opened and scanned.
  61  *                nkeys    -- number of keys
  62  *                skeys    -- keys to restrict scanning
  63  *                       isindex  -- if this is true, the relation is the relid of
  64  *                                               an index relation, else it is a heap relation.
  65  *              Returns the relation as(relDesc scanDesc)
  66  * ----------------------------------------------------------------
  67  */
  68 void
  69 ExecOpenScanR(Oid relOid,
  70                           int nkeys,
  71                           ScanKey skeys,
  72                           bool isindex,
  73                           ScanDirection dir,
  74                           Snapshot snapshot,
  75                           Relation *returnRelation, /* return */
  76                           Pointer *returnScanDesc)      /* return */
  77 {
  78         Relation        relation;
  79         Pointer         scanDesc;
  80
  81         /* ----------------
  82          *      note: scanDesc returned by ExecBeginScan can be either
  83          *                a HeapScanDesc or an IndexScanDesc so for now we
  84          *                make it a Pointer.  There should be a better scan
  85          *                abstraction someday -cim 9/9/89
  86          * ----------------
  87          */
  88
  89         /* ----------------
  90          *      Open the relation with the correct call depending
  91          *      on whether this is a heap relation or an index relation.
  92          *
  93          *      For a table, acquire AccessShareLock for the duration of the query
  94          *      execution.  For indexes, acquire no lock here; the index machinery
  95          *      does its own locks and unlocks.  (We rely on having some kind of
  96          *      lock on the parent table to ensure the index won't go away!)
  97          * ----------------
  98          */
  99         if (isindex)
 100                 relation = index_open(relOid);
 101         else
 102                 relation = heap_open(relOid, AccessShareLock);
 103
 104         scanDesc = ExecBeginScan(relation,
 105                                                          nkeys,
 106                                                          skeys,
 107                                                          isindex,
 108                                                          dir,
 109                                                          snapshot);
 110
 111         if (returnRelation != NULL)
 112                 *returnRelation = relation;
 113         if (scanDesc != NULL)
 114                 *returnScanDesc = scanDesc;
 115 }
 116
 117 /* ----------------------------------------------------------------
 118  *              ExecBeginScan
 119  *
 120  *              beginscans a relation in current direction.
 121  *
 122  *              XXX fix parameters to AMbeginscan (and btbeginscan)
 123  *                              currently we need to pass a flag stating whether
 124  *                              or not the scan should begin at an endpoint of
 125  *                              the relation.. Right now we always pass false
 126  *                              -cim 9/14/89
 127  * ----------------------------------------------------------------
 128  */
 129 static Pointer
 130 ExecBeginScan(Relation relation,
 131                           int nkeys,
 132                           ScanKey skeys,
 133                           bool isindex,
 134                           ScanDirection dir,
 135                           Snapshot snapshot)
 136 {
 137         Pointer         scanDesc;
 138
 139         /* ----------------
 140          *      open the appropriate type of scan.
 141          *
 142          *      Note: ambeginscan()'s second arg is a boolean indicating
 143          *                that the scan should be done in reverse..  That is,
 144          *                if you pass it true, then the scan is backward.
 145          * ----------------
 146          */
 147         if (isindex)
 148         {
 149                 scanDesc = (Pointer) index_beginscan(relation,
 150                                                                                          false,         /* see above comment */
 151                                                                                          nkeys,
 152                                                                                          skeys);
 153         }
 154         else
 155         {
 156                 scanDesc = (Pointer) heap_beginscan(relation,
 157                                                                                         ScanDirectionIsBackward(dir),
 158                                                                                         snapshot,
 159                                                                                         nkeys,
 160                                                                                         skeys);
 161         }
 162
 163         if (scanDesc == NULL)
 164                 elog(DEBUG, "ExecBeginScan: scanDesc = NULL, heap_beginscan failed.");
 165
 166         return scanDesc;
 167 }
 168
 169 /* ----------------------------------------------------------------
 170  *              ExecCloseR
 171  *
 172  *              closes the relation and scan descriptor for a scan node.
 173  *              Also closes index relations and scans for index scans.
 174  * ----------------------------------------------------------------
 175  */
 176 void
 177 ExecCloseR(Plan *node)
 178 {
 179         CommonScanState *state;
 180         Relation        relation;
 181         HeapScanDesc scanDesc;
 182
 183         /* ----------------
 184          *      get state for node and shut down the heap scan, if any
 185          * ----------------
 186          */
 187         switch (nodeTag(node))
 188         {
 189                 case T_SeqScan:
 190                         state = ((SeqScan *) node)->scanstate;
 191                         break;
 192
 193                 case T_IndexScan:
 194                         state = ((IndexScan *) node)->scan.scanstate;
 195                         break;
 196
 197                 case T_TidScan:
 198                         state = ((TidScan *) node)->scan.scanstate;
 199                         break;
 200
 201                 default:
 202                         elog(DEBUG, "ExecCloseR: not a scan node!");
 203                         return;
 204         }
 205
 206         relation = state->css_currentRelation;
 207         scanDesc = state->css_currentScanDesc;
 208
 209         if (scanDesc != NULL)
 210                 heap_endscan(scanDesc);
 211
 212         /* ----------------
 213          *      if this is an index scan then we have to take care
 214          *      of the index relations as well.
 215          * ----------------
 216          */
 217         if (IsA(node, IndexScan))
 218         {
 219                 IndexScan  *iscan = (IndexScan *) node;
 220                 IndexScanState *indexstate = iscan->indxstate;
 221                 int                     numIndices;
 222                 RelationPtr indexRelationDescs;
 223                 IndexScanDescPtr indexScanDescs;
 224                 int                     i;
 225
 226                 numIndices = indexstate->iss_NumIndices;
 227                 indexRelationDescs = indexstate->iss_RelationDescs;
 228                 indexScanDescs = indexstate->iss_ScanDescs;
 229
 230                 for (i = 0; i < numIndices; i++)
 231                 {
 232                         /* ----------------
 233                          *      shut down each of the index scans and
 234                          *      close each of the index relations
 235                          * ----------------
 236                          */
 237                         if (indexScanDescs[i] != NULL)
 238                                 index_endscan(indexScanDescs[i]);
 239
 240                         if (indexRelationDescs[i] != NULL)
 241                                 index_close(indexRelationDescs[i]);
 242                 }
 243         }
 244
 245         /*
 246          * Finally, close the heap relation.
 247          *
 248          * Currently, we do not release the AccessShareLock acquired by
 249          * ExecOpenScanR.  This lock should be held till end of transaction.
 250          * (There is a faction that considers this too much locking, however.)
 251          */
 252         if (relation != NULL)
 253                 heap_close(relation, NoLock);
 254 }
 255
 256 /* ----------------------------------------------------------------
 257  *              ExecReScan
 258  *
 259  *              XXX this should be extended to cope with all the node types..
 260  *
 261  *              takes the new expression context as an argument, so that
 262  *              index scans needn't have their scan keys updated separately
 263  *              - marcel 09/20/94
 264  * ----------------------------------------------------------------
 265  */
 266 void
 267 ExecReScan(Plan *node, ExprContext *exprCtxt, Plan *parent)
 268 {
 269
 270         if (node->chgParam != NULL) /* Wow! */
 271         {
 272                 List       *lst;
 273
 274                 foreach(lst, node->initPlan)
 275                 {
 276                         Plan       *splan = ((SubPlan *) lfirst(lst))->plan;
 277
 278                         if (splan->extParam != NULL)            /* don't care about child
 279                                                                                                  * locParam */
 280                                 SetChangedParamList(splan, node->chgParam);
 281                         if (splan->chgParam != NULL)
 282                                 ExecReScanSetParamPlan((SubPlan *) lfirst(lst), node);
 283                 }
 284                 foreach(lst, node->subPlan)
 285                 {
 286                         Plan       *splan = ((SubPlan *) lfirst(lst))->plan;
 287
 288                         if (splan->extParam != NULL)
 289                                 SetChangedParamList(splan, node->chgParam);
 290                 }
 291                 /* Well. Now set chgParam for left/right trees. */
 292                 if (node->lefttree != NULL)
 293                         SetChangedParamList(node->lefttree, node->chgParam);
 294                 if (node->righttree != NULL)
 295                         SetChangedParamList(node->righttree, node->chgParam);
 296         }
 297
 298         switch (nodeTag(node))
 299         {
 300                 case T_SeqScan:
 301                         ExecSeqReScan((SeqScan *) node, exprCtxt, parent);
 302                         break;
 303
 304                 case T_IndexScan:
 305                         ExecIndexReScan((IndexScan *) node, exprCtxt, parent);
 306                         break;
 307
 308                 case T_TidScan:
 309                         ExecTidReScan((TidScan *) node, exprCtxt, parent);
 310                         break;
 311
 312                 case T_SubqueryScan:
 313                         ExecSubqueryReScan((SubqueryScan *) node, exprCtxt, parent);
 314                         break;
 315
 316                 case T_Material:
 317                         ExecMaterialReScan((Material *) node, exprCtxt, parent);
 318                         break;
 319
 320                 case T_NestLoop:
 321                         ExecReScanNestLoop((NestLoop *) node, exprCtxt, parent);
 322                         break;
 323
 324                 case T_HashJoin:
 325                         ExecReScanHashJoin((HashJoin *) node, exprCtxt, parent);
 326                         break;
 327
 328                 case T_Hash:
 329                         ExecReScanHash((Hash *) node, exprCtxt, parent);
 330                         break;
 331
 332                 case T_Agg:
 333                         ExecReScanAgg((Agg *) node, exprCtxt, parent);
 334                         break;
 335
 336                 case T_Group:
 337                         ExecReScanGroup((Group *) node, exprCtxt, parent);
 338                         break;
 339
 340                 case T_Result:
 341                         ExecReScanResult((Result *) node, exprCtxt, parent);
 342                         break;
 343
 344                 case T_Unique:
 345                         ExecReScanUnique((Unique *) node, exprCtxt, parent);
 346                         break;
 347
 348                 case T_SetOp:
 349                         ExecReScanSetOp((SetOp *) node, exprCtxt, parent);
 350                         break;
 351
 352                 case T_Limit:
 353                         ExecReScanLimit((Limit *) node, exprCtxt, parent);
 354                         break;
 355
 356                 case T_Sort:
 357                         ExecReScanSort((Sort *) node, exprCtxt, parent);
 358                         break;
 359
 360                 case T_MergeJoin:
 361                         ExecReScanMergeJoin((MergeJoin *) node, exprCtxt, parent);
 362                         break;
 363
 364                 case T_Append:
 365                         ExecReScanAppend((Append *) node, exprCtxt, parent);
 366                         break;
 367
 368                 default:
 369                         elog(ERROR, "ExecReScan: node type %d not supported",
 370                                  nodeTag(node));
 371                         return;
 372         }
 373
 374         if (node->chgParam != NULL)
 375         {
 376                 freeList(node->chgParam);
 377                 node->chgParam = NULL;
 378         }
 379 }
 380
 381 /* ----------------------------------------------------------------
 382  *              ExecReScanR
 383  *
 384  *              XXX this does not do the right thing with indices yet.
 385  * ----------------------------------------------------------------
 386  */
 387 HeapScanDesc
 388 ExecReScanR(Relation relDesc,   /* LLL relDesc unused  */
 389                         HeapScanDesc scanDesc,
 390                         ScanDirection direction,
 391                         int nkeys,                      /* LLL nkeys unused  */
 392                         ScanKey skeys)
 393 {
 394         if (scanDesc != NULL)
 395                 heap_rescan(scanDesc,   /* scan desc */
 396                                         ScanDirectionIsBackward(direction), /* backward flag */
 397                                         skeys);         /* scan keys */
 398
 399         return scanDesc;
 400 }
 401
 402 /* ----------------------------------------------------------------
 403  *              ExecMarkPos
 404  *
 405  *              Marks the current scan position.
 406  *
 407  *              XXX Needs to be extended to include all the node types,
 408  *              or at least all the ones that can be directly below a mergejoin.
 409  * ----------------------------------------------------------------
 410  */
 411 void
 412 ExecMarkPos(Plan *node)
 413 {
 414         switch (nodeTag(node))
 415         {
 416                 case T_SeqScan:
 417                         ExecSeqMarkPos((SeqScan *) node);
 418                         break;
 419
 420                 case T_IndexScan:
 421                         ExecIndexMarkPos((IndexScan *) node);
 422                         break;
 423
 424                 case T_Material:
 425                         ExecMaterialMarkPos((Material *) node);
 426                         break;
 427
 428                 case T_Sort:
 429                         ExecSortMarkPos((Sort *) node);
 430                         break;
 431
 432                 case T_TidScan:
 433                         ExecTidMarkPos((TidScan *) node);
 434                         break;
 435
 436                 default:
 437                         /* don't make hard error unless caller asks to restore... */
 438                         elog(DEBUG, "ExecMarkPos: node type %d not supported",
 439                                  nodeTag(node));
 440                         break;
 441         }
 442 }
 443
 444 /* ----------------------------------------------------------------
 445  *              ExecRestrPos
 446  *
 447  *              restores the scan position previously saved with ExecMarkPos()
 448  *
 449  *              XXX Needs to be extended to include all the node types,
 450  *              or at least all the ones that can be directly below a mergejoin.
 451  * ----------------------------------------------------------------
 452  */
 453 void
 454 ExecRestrPos(Plan *node)
 455 {
 456         switch (nodeTag(node))
 457         {
 458                 case T_SeqScan:
 459                         ExecSeqRestrPos((SeqScan *) node);
 460                         break;
 461
 462                 case T_IndexScan:
 463                         ExecIndexRestrPos((IndexScan *) node);
 464                         break;
 465
 466                 case T_Material:
 467                         ExecMaterialRestrPos((Material *) node);
 468                         break;
 469
 470                 case T_Sort:
 471                         ExecSortRestrPos((Sort *) node);
 472                         break;
 473
 474                 default:
 475                         elog(ERROR, "ExecRestrPos: node type %d not supported",
 476                                  nodeTag(node));
 477                         break;
 478         }
 479 }