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

   1 /*-------------------------------------------------------------------------
   2  *
   3  * nodeModifyTable.c
   4  *        routines to handle ModifyTable nodes.
   5  *
   6  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/backend/executor/nodeModifyTable.c
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 /* INTERFACE ROUTINES
  16  *              ExecInitModifyTable - initialize the ModifyTable node
  17  *              ExecModifyTable         - retrieve the next tuple from the node
  18  *              ExecEndModifyTable      - shut down the ModifyTable node
  19  *              ExecReScanModifyTable - rescan the ModifyTable node
  20  *
  21  *       NOTES
  22  *              Each ModifyTable node contains a list of one or more subplans,
  23  *              much like an Append node.  There is one subplan per result relation.
  24  *              The key reason for this is that in an inherited UPDATE command, each
  25  *              result relation could have a different schema (more or different
  26  *              columns) requiring a different plan tree to produce it.  In an
  27  *              inherited DELETE, all the subplans should produce the same output
  28  *              rowtype, but we might still find that different plans are appropriate
  29  *              for different child relations.
  30  *
  31  *              If the query specifies RETURNING, then the ModifyTable returns a
  32  *              RETURNING tuple after completing each row insert, update, or delete.
  33  *              It must be called again to continue the operation.      Without RETURNING,
  34  *              we just loop within the node until all the work is done, then
  35  *              return NULL.  This avoids useless call/return overhead.
  36  */
  37
  38 #include "postgres.h"
  39
  40 #include "access/xact.h"
  41 #include "commands/trigger.h"
  42 #include "executor/executor.h"
  43 #include "executor/nodeModifyTable.h"
  44 #include "miscadmin.h"
  45 #include "nodes/nodeFuncs.h"
  46 #include "storage/bufmgr.h"
  47 #include "utils/builtins.h"
  48 #include "utils/memutils.h"
  49 #include "utils/tqual.h"
  50
  51
  52 /*
  53  * Verify that the tuples to be produced by INSERT or UPDATE match the
  54  * target relation's rowtype
  55  *
  56  * We do this to guard against stale plans.  If plan invalidation is
  57  * functioning properly then we should never get a failure here, but better
  58  * safe than sorry.  Note that this is called after we have obtained lock
  59  * on the target rel, so the rowtype can't change underneath us.
  60  *
  61  * The plan output is represented by its targetlist, because that makes
  62  * handling the dropped-column case easier.
  63  */
  64 static void
  65 ExecCheckPlanOutput(Relation resultRel, List *targetList)
  66 {
  67         TupleDesc       resultDesc = RelationGetDescr(resultRel);
  68         int                     attno = 0;
  69         ListCell   *lc;
  70
  71         foreach(lc, targetList)
  72         {
  73                 TargetEntry *tle = (TargetEntry *) lfirst(lc);
  74                 Form_pg_attribute attr;
  75
  76                 if (tle->resjunk)
  77                         continue;                       /* ignore junk tlist items */
  78
  79                 if (attno >= resultDesc->natts)
  80                         ereport(ERROR,
  81                                         (errcode(ERRCODE_DATATYPE_MISMATCH),
  82                                          errmsg("table row type and query-specified row type do not match"),
  83                                          errdetail("Query has too many columns.")));
  84                 attr = resultDesc->attrs[attno++];
  85
  86                 if (!attr->attisdropped)
  87                 {
  88                         /* Normal case: demand type match */
  89                         if (exprType((Node *) tle->expr) != attr->atttypid)
  90                                 ereport(ERROR,
  91                                                 (errcode(ERRCODE_DATATYPE_MISMATCH),
  92                                                  errmsg("table row type and query-specified row type do not match"),
  93                                                  errdetail("Table has type %s at ordinal position %d, but query expects %s.",
  94                                                                    format_type_be(attr->atttypid),
  95                                                                    attno,
  96                                                          format_type_be(exprType((Node *) tle->expr)))));
  97                 }
  98                 else
  99                 {
 100                         /*
 101                          * For a dropped column, we can't check atttypid (it's likely 0).
 102                          * In any case the planner has most likely inserted an INT4 null.
 103                          * What we insist on is just *some* NULL constant.
 104                          */
 105                         if (!IsA(tle->expr, Const) ||
 106                                 !((Const *) tle->expr)->constisnull)
 107                                 ereport(ERROR,
 108                                                 (errcode(ERRCODE_DATATYPE_MISMATCH),
 109                                                  errmsg("table row type and query-specified row type do not match"),
 110                                                  errdetail("Query provides a value for a dropped column at ordinal position %d.",
 111                                                                    attno)));
 112                 }
 113         }
 114         if (attno != resultDesc->natts)
 115                 ereport(ERROR,
 116                                 (errcode(ERRCODE_DATATYPE_MISMATCH),
 117                   errmsg("table row type and query-specified row type do not match"),
 118                                  errdetail("Query has too few columns.")));
 119 }
 120
 121 /*
 122  * ExecProcessReturning --- evaluate a RETURNING list
 123  *
 124  * projectReturning: RETURNING projection info for current result rel
 125  * tupleSlot: slot holding tuple actually inserted/updated/deleted
 126  * planSlot: slot holding tuple returned by top subplan node
 127  *
 128  * Returns a slot holding the result tuple
 129  */
 130 static TupleTableSlot *
 131 ExecProcessReturning(ProjectionInfo *projectReturning,
 132                                          TupleTableSlot *tupleSlot,
 133                                          TupleTableSlot *planSlot)
 134 {
 135         ExprContext *econtext = projectReturning->pi_exprContext;
 136
 137         /*
 138          * Reset per-tuple memory context to free any expression evaluation
 139          * storage allocated in the previous cycle.
 140          */
 141         ResetExprContext(econtext);
 142
 143         /* Make tuple and any needed join variables available to ExecProject */
 144         econtext->ecxt_scantuple = tupleSlot;
 145         econtext->ecxt_outertuple = planSlot;
 146
 147         /* Compute the RETURNING expressions */
 148         return ExecProject(projectReturning, NULL);
 149 }
 150
 151 /* ----------------------------------------------------------------
 152  *              ExecInsert
 153  *
 154  *              For INSERT, we have to insert the tuple into the target relation
 155  *              and insert appropriate tuples into the index relations.
 156  *
 157  *              Returns RETURNING result if any, otherwise NULL.
 158  * ----------------------------------------------------------------
 159  */
 160 static TupleTableSlot *
 161 ExecInsert(TupleTableSlot *slot,
 162                    TupleTableSlot *planSlot,
 163                    EState *estate)
 164 {
 165         HeapTuple       tuple;
 166         ResultRelInfo *resultRelInfo;
 167         Relation        resultRelationDesc;
 168         Oid                     newId;
 169         List       *recheckIndexes = NIL;
 170
 171         /*
 172          * get the heap tuple out of the tuple table slot, making sure we have a
 173          * writable copy
 174          */
 175         tuple = ExecMaterializeSlot(slot);
 176
 177         /*
 178          * get information on the (current) result relation
 179          */
 180         resultRelInfo = estate->es_result_relation_info;
 181         resultRelationDesc = resultRelInfo->ri_RelationDesc;
 182
 183         /*
 184          * If the result relation has OIDs, force the tuple's OID to zero so that
 185          * heap_insert will assign a fresh OID.  Usually the OID already will be
 186          * zero at this point, but there are corner cases where the plan tree can
 187          * return a tuple extracted literally from some table with the same
 188          * rowtype.
 189          *
 190          * XXX if we ever wanted to allow users to assign their own OIDs to new
 191          * rows, this'd be the place to do it.  For the moment, we make a point of
 192          * doing this before calling triggers, so that a user-supplied trigger
 193          * could hack the OID if desired.
 194          */
 195         if (resultRelationDesc->rd_rel->relhasoids)
 196                 HeapTupleSetOid(tuple, InvalidOid);
 197
 198         /* BEFORE ROW INSERT Triggers */
 199         if (resultRelInfo->ri_TrigDesc &&
 200                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
 201         {
 202                 HeapTuple       newtuple;
 203
 204                 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
 205
 206                 if (newtuple == NULL)   /* "do nothing" */
 207                         return NULL;
 208
 209                 if (newtuple != tuple)  /* modified by Trigger(s) */
 210                 {
 211                         /*
 212                          * Put the modified tuple into a slot for convenience of routines
 213                          * below.  We assume the tuple was allocated in per-tuple memory
 214                          * context, and therefore will go away by itself. The tuple table
 215                          * slot should not try to clear it.
 216                          */
 217                         TupleTableSlot *newslot = estate->es_trig_tuple_slot;
 218                         TupleDesc       tupdesc = RelationGetDescr(resultRelationDesc);
 219
 220                         if (newslot->tts_tupleDescriptor != tupdesc)
 221                                 ExecSetSlotDescriptor(newslot, tupdesc);
 222                         ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
 223                         slot = newslot;
 224                         tuple = newtuple;
 225                 }
 226         }
 227
 228         /*
 229          * Check the constraints of the tuple
 230          */
 231         if (resultRelationDesc->rd_att->constr)
 232                 ExecConstraints(resultRelInfo, slot, estate);
 233
 234         /*
 235          * insert the tuple
 236          *
 237          * Note: heap_insert returns the tid (location) of the new tuple in the
 238          * t_self field.
 239          */
 240         newId = heap_insert(resultRelationDesc, tuple,
 241                                                 estate->es_output_cid, 0, NULL);
 242
 243         (estate->es_processed)++;
 244         estate->es_lastoid = newId;
 245         setLastTid(&(tuple->t_self));
 246
 247         /*
 248          * insert index entries for tuple
 249          */
 250         if (resultRelInfo->ri_NumIndices > 0)
 251                 recheckIndexes = ExecInsertIndexTuples(slot, &(tuple->t_self),
 252                                                                                            estate);
 253
 254         /* AFTER ROW INSERT Triggers */
 255         ExecARInsertTriggers(estate, resultRelInfo, tuple, recheckIndexes);
 256
 257         list_free(recheckIndexes);
 258
 259         /* Process RETURNING if present */
 260         if (resultRelInfo->ri_projectReturning)
 261                 return ExecProcessReturning(resultRelInfo->ri_projectReturning,
 262                                                                         slot, planSlot);
 263
 264         return NULL;
 265 }
 266
 267 /* ----------------------------------------------------------------
 268  *              ExecDelete
 269  *
 270  *              DELETE is like UPDATE, except that we delete the tuple and no
 271  *              index modifications are needed
 272  *
 273  *              Returns RETURNING result if any, otherwise NULL.
 274  * ----------------------------------------------------------------
 275  */
 276 static TupleTableSlot *
 277 ExecDelete(ItemPointer tupleid,
 278                    TupleTableSlot *planSlot,
 279                    EPQState *epqstate,
 280                    EState *estate)
 281 {
 282         ResultRelInfo *resultRelInfo;
 283         Relation        resultRelationDesc;
 284         HTSU_Result result;
 285         ItemPointerData update_ctid;
 286         TransactionId update_xmax;
 287
 288         /*
 289          * get information on the (current) result relation
 290          */
 291         resultRelInfo = estate->es_result_relation_info;
 292         resultRelationDesc = resultRelInfo->ri_RelationDesc;
 293
 294         /* BEFORE ROW DELETE Triggers */
 295         if (resultRelInfo->ri_TrigDesc &&
 296                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
 297         {
 298                 bool            dodelete;
 299
 300                 dodelete = ExecBRDeleteTriggers(estate, epqstate, resultRelInfo,
 301                                                                                 tupleid);
 302
 303                 if (!dodelete)                  /* "do nothing" */
 304                         return NULL;
 305         }
 306
 307         /*
 308          * delete the tuple
 309          *
 310          * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that
 311          * the row to be deleted is visible to that snapshot, and throw a can't-
 312          * serialize error if not.      This is a special-case behavior needed for
 313          * referential integrity updates in transaction-snapshot mode transactions.
 314          */
 315 ldelete:;
 316         result = heap_delete(resultRelationDesc, tupleid,
 317                                                  &update_ctid, &update_xmax,
 318                                                  estate->es_output_cid,
 319                                                  estate->es_crosscheck_snapshot,
 320                                                  true /* wait for commit */ );
 321         switch (result)
 322         {
 323                 case HeapTupleSelfUpdated:
 324                         /* already deleted by self; nothing to do */
 325                         return NULL;
 326
 327                 case HeapTupleMayBeUpdated:
 328                         break;
 329
 330                 case HeapTupleUpdated:
 331                         if (IsolationUsesXactSnapshot())
 332                                 ereport(ERROR,
 333                                                 (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
 334                                                  errmsg("could not serialize access due to concurrent update")));
 335                         if (!ItemPointerEquals(tupleid, &update_ctid))
 336                         {
 337                                 TupleTableSlot *epqslot;
 338
 339                                 epqslot = EvalPlanQual(estate,
 340                                                                            epqstate,
 341                                                                            resultRelationDesc,
 342                                                                            resultRelInfo->ri_RangeTableIndex,
 343                                                                            &update_ctid,
 344                                                                            update_xmax);
 345                                 if (!TupIsNull(epqslot))
 346                                 {
 347                                         *tupleid = update_ctid;
 348                                         goto ldelete;
 349                                 }
 350                         }
 351                         /* tuple already deleted; nothing to do */
 352                         return NULL;
 353
 354                 default:
 355                         elog(ERROR, "unrecognized heap_delete status: %u", result);
 356                         return NULL;
 357         }
 358
 359         (estate->es_processed)++;
 360
 361         /*
 362          * Note: Normally one would think that we have to delete index tuples
 363          * associated with the heap tuple now...
 364          *
 365          * ... but in POSTGRES, we have no need to do this because VACUUM will
 366          * take care of it later.  We can't delete index tuples immediately
 367          * anyway, since the tuple is still visible to other transactions.
 368          */
 369
 370         /* AFTER ROW DELETE Triggers */
 371         ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
 372
 373         /* Process RETURNING if present */
 374         if (resultRelInfo->ri_projectReturning)
 375         {
 376                 /*
 377                  * We have to put the target tuple into a slot, which means first we
 378                  * gotta fetch it.      We can use the trigger tuple slot.
 379                  */
 380                 TupleTableSlot *slot = estate->es_trig_tuple_slot;
 381                 TupleTableSlot *rslot;
 382                 HeapTupleData deltuple;
 383                 Buffer          delbuffer;
 384
 385                 deltuple.t_self = *tupleid;
 386                 if (!heap_fetch(resultRelationDesc, SnapshotAny,
 387                                                 &deltuple, &delbuffer, false, NULL))
 388                         elog(ERROR, "failed to fetch deleted tuple for DELETE RETURNING");
 389
 390                 if (slot->tts_tupleDescriptor != RelationGetDescr(resultRelationDesc))
 391                         ExecSetSlotDescriptor(slot, RelationGetDescr(resultRelationDesc));
 392                 ExecStoreTuple(&deltuple, slot, InvalidBuffer, false);
 393
 394                 rslot = ExecProcessReturning(resultRelInfo->ri_projectReturning,
 395                                                                          slot, planSlot);
 396
 397                 ExecClearTuple(slot);
 398                 ReleaseBuffer(delbuffer);
 399
 400                 return rslot;
 401         }
 402
 403         return NULL;
 404 }
 405
 406 /* ----------------------------------------------------------------
 407  *              ExecUpdate
 408  *
 409  *              note: we can't run UPDATE queries with transactions
 410  *              off because UPDATEs are actually INSERTs and our
 411  *              scan will mistakenly loop forever, updating the tuple
 412  *              it just inserted..      This should be fixed but until it
 413  *              is, we don't want to get stuck in an infinite loop
 414  *              which corrupts your database..
 415  *
 416  *              Returns RETURNING result if any, otherwise NULL.
 417  * ----------------------------------------------------------------
 418  */
 419 static TupleTableSlot *
 420 ExecUpdate(ItemPointer tupleid,
 421                    TupleTableSlot *slot,
 422                    TupleTableSlot *planSlot,
 423                    EPQState *epqstate,
 424                    EState *estate)
 425 {
 426         HeapTuple       tuple;
 427         ResultRelInfo *resultRelInfo;
 428         Relation        resultRelationDesc;
 429         HTSU_Result result;
 430         ItemPointerData update_ctid;
 431         TransactionId update_xmax;
 432         List       *recheckIndexes = NIL;
 433
 434         /*
 435          * abort the operation if not running transactions
 436          */
 437         if (IsBootstrapProcessingMode())
 438                 elog(ERROR, "cannot UPDATE during bootstrap");
 439
 440         /*
 441          * get the heap tuple out of the tuple table slot, making sure we have a
 442          * writable copy
 443          */
 444         tuple = ExecMaterializeSlot(slot);
 445
 446         /*
 447          * get information on the (current) result relation
 448          */
 449         resultRelInfo = estate->es_result_relation_info;
 450         resultRelationDesc = resultRelInfo->ri_RelationDesc;
 451
 452         /* BEFORE ROW UPDATE Triggers */
 453         if (resultRelInfo->ri_TrigDesc &&
 454                 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
 455         {
 456                 HeapTuple       newtuple;
 457
 458                 newtuple = ExecBRUpdateTriggers(estate, epqstate, resultRelInfo,
 459                                                                                 tupleid, tuple);
 460
 461                 if (newtuple == NULL)   /* "do nothing" */
 462                         return NULL;
 463
 464                 if (newtuple != tuple)  /* modified by Trigger(s) */
 465                 {
 466                         /*
 467                          * Put the modified tuple into a slot for convenience of routines
 468                          * below.  We assume the tuple was allocated in per-tuple memory
 469                          * context, and therefore will go away by itself. The tuple table
 470                          * slot should not try to clear it.
 471                          */
 472                         TupleTableSlot *newslot = estate->es_trig_tuple_slot;
 473                         TupleDesc       tupdesc = RelationGetDescr(resultRelationDesc);
 474
 475                         if (newslot->tts_tupleDescriptor != tupdesc)
 476                                 ExecSetSlotDescriptor(newslot, tupdesc);
 477                         ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
 478                         slot = newslot;
 479                         tuple = newtuple;
 480                 }
 481         }
 482
 483         /*
 484          * Check the constraints of the tuple
 485          *
 486          * If we generate a new candidate tuple after EvalPlanQual testing, we
 487          * must loop back here and recheck constraints.  (We don't need to redo
 488          * triggers, however.  If there are any BEFORE triggers then trigger.c
 489          * will have done heap_lock_tuple to lock the correct tuple, so there's no
 490          * need to do them again.)
 491          */
 492 lreplace:;
 493         if (resultRelationDesc->rd_att->constr)
 494                 ExecConstraints(resultRelInfo, slot, estate);
 495
 496         /*
 497          * replace the heap tuple
 498          *
 499          * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that
 500          * the row to be updated is visible to that snapshot, and throw a can't-
 501          * serialize error if not.      This is a special-case behavior needed for
 502          * referential integrity updates in transaction-snapshot mode transactions.
 503          */
 504         result = heap_update(resultRelationDesc, tupleid, tuple,
 505                                                  &update_ctid, &update_xmax,
 506                                                  estate->es_output_cid,
 507                                                  estate->es_crosscheck_snapshot,
 508                                                  true /* wait for commit */ );
 509         switch (result)
 510         {
 511                 case HeapTupleSelfUpdated:
 512                         /* already deleted by self; nothing to do */
 513                         return NULL;
 514
 515                 case HeapTupleMayBeUpdated:
 516                         break;
 517
 518                 case HeapTupleUpdated:
 519                         if (IsolationUsesXactSnapshot())
 520                                 ereport(ERROR,
 521                                                 (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
 522                                                  errmsg("could not serialize access due to concurrent update")));
 523                         if (!ItemPointerEquals(tupleid, &update_ctid))
 524                         {
 525                                 TupleTableSlot *epqslot;
 526
 527                                 epqslot = EvalPlanQual(estate,
 528                                                                            epqstate,
 529                                                                            resultRelationDesc,
 530                                                                            resultRelInfo->ri_RangeTableIndex,
 531                                                                            &update_ctid,
 532                                                                            update_xmax);
 533                                 if (!TupIsNull(epqslot))
 534                                 {
 535                                         *tupleid = update_ctid;
 536                                         slot = ExecFilterJunk(resultRelInfo->ri_junkFilter, epqslot);
 537                                         tuple = ExecMaterializeSlot(slot);
 538                                         goto lreplace;
 539                                 }
 540                         }
 541                         /* tuple already deleted; nothing to do */
 542                         return NULL;
 543
 544                 default:
 545                         elog(ERROR, "unrecognized heap_update status: %u", result);
 546                         return NULL;
 547         }
 548
 549         (estate->es_processed)++;
 550
 551         /*
 552          * Note: instead of having to update the old index tuples associated with
 553          * the heap tuple, all we do is form and insert new index tuples. This is
 554          * because UPDATEs are actually DELETEs and INSERTs, and index tuple
 555          * deletion is done later by VACUUM (see notes in ExecDelete).  All we do
 556          * here is insert new index tuples.  -cim 9/27/89
 557          */
 558
 559         /*
 560          * insert index entries for tuple
 561          *
 562          * Note: heap_update returns the tid (location) of the new tuple in the
 563          * t_self field.
 564          *
 565          * If it's a HOT update, we mustn't insert new index entries.
 566          */
 567         if (resultRelInfo->ri_NumIndices > 0 && !HeapTupleIsHeapOnly(tuple))
 568                 recheckIndexes = ExecInsertIndexTuples(slot, &(tuple->t_self),
 569                                                                                            estate);
 570
 571         /* AFTER ROW UPDATE Triggers */
 572         ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple,
 573                                                  recheckIndexes);
 574
 575         list_free(recheckIndexes);
 576
 577         /* Process RETURNING if present */
 578         if (resultRelInfo->ri_projectReturning)
 579                 return ExecProcessReturning(resultRelInfo->ri_projectReturning,
 580                                                                         slot, planSlot);
 581
 582         return NULL;
 583 }
 584
 585
 586 /*
 587  * Process BEFORE EACH STATEMENT triggers
 588  */
 589 static void
 590 fireBSTriggers(ModifyTableState *node)
 591 {
 592         switch (node->operation)
 593         {
 594                 case CMD_INSERT:
 595                         ExecBSInsertTriggers(node->ps.state,
 596                                                                  node->ps.state->es_result_relations);
 597                         break;
 598                 case CMD_UPDATE:
 599                         ExecBSUpdateTriggers(node->ps.state,
 600                                                                  node->ps.state->es_result_relations);
 601                         break;
 602                 case CMD_DELETE:
 603                         ExecBSDeleteTriggers(node->ps.state,
 604                                                                  node->ps.state->es_result_relations);
 605                         break;
 606                 default:
 607                         elog(ERROR, "unknown operation");
 608                         break;
 609         }
 610 }
 611
 612 /*
 613  * Process AFTER EACH STATEMENT triggers
 614  */
 615 static void
 616 fireASTriggers(ModifyTableState *node)
 617 {
 618         switch (node->operation)
 619         {
 620                 case CMD_INSERT:
 621                         ExecASInsertTriggers(node->ps.state,
 622                                                                  node->ps.state->es_result_relations);
 623                         break;
 624                 case CMD_UPDATE:
 625                         ExecASUpdateTriggers(node->ps.state,
 626                                                                  node->ps.state->es_result_relations);
 627                         break;
 628                 case CMD_DELETE:
 629                         ExecASDeleteTriggers(node->ps.state,
 630                                                                  node->ps.state->es_result_relations);
 631                         break;
 632                 default:
 633                         elog(ERROR, "unknown operation");
 634                         break;
 635         }
 636 }
 637
 638
 639 /* ----------------------------------------------------------------
 640  *         ExecModifyTable
 641  *
 642  *              Perform table modifications as required, and return RETURNING results
 643  *              if needed.
 644  * ----------------------------------------------------------------
 645  */
 646 TupleTableSlot *
 647 ExecModifyTable(ModifyTableState *node)
 648 {
 649         EState     *estate = node->ps.state;
 650         CmdType         operation = node->operation;
 651         PlanState  *subplanstate;
 652         JunkFilter *junkfilter;
 653         TupleTableSlot *slot;
 654         TupleTableSlot *planSlot;
 655         ItemPointer tupleid = NULL;
 656         ItemPointerData tuple_ctid;
 657
 658         /*
 659          * On first call, fire BEFORE STATEMENT triggers before proceeding.
 660          */
 661         if (node->fireBSTriggers)
 662         {
 663                 fireBSTriggers(node);
 664                 node->fireBSTriggers = false;
 665         }
 666
 667         /*
 668          * es_result_relation_info must point to the currently active result
 669          * relation.  (Note we assume that ModifyTable nodes can't be nested.) We
 670          * want it to be NULL whenever we're not within ModifyTable, though.
 671          */
 672         estate->es_result_relation_info =
 673                 estate->es_result_relations + node->mt_whichplan;
 674
 675         /* Preload local variables */
 676         subplanstate = node->mt_plans[node->mt_whichplan];
 677         junkfilter = estate->es_result_relation_info->ri_junkFilter;
 678
 679         /*
 680          * Fetch rows from subplan(s), and execute the required table modification
 681          * for each row.
 682          */
 683         for (;;)
 684         {
 685                 /*
 686                  * Reset the per-output-tuple exprcontext.  This is needed because
 687                  * triggers expect to use that context as workspace.  It's a bit ugly
 688                  * to do this below the top level of the plan, however.  We might need
 689                  * to rethink this later.
 690                  */
 691                 ResetPerTupleExprContext(estate);
 692
 693                 planSlot = ExecProcNode(subplanstate);
 694
 695                 if (TupIsNull(planSlot))
 696                 {
 697                         /* advance to next subplan if any */
 698                         node->mt_whichplan++;
 699                         if (node->mt_whichplan < node->mt_nplans)
 700                         {
 701                                 estate->es_result_relation_info++;
 702                                 subplanstate = node->mt_plans[node->mt_whichplan];
 703                                 junkfilter = estate->es_result_relation_info->ri_junkFilter;
 704                                 EvalPlanQualSetPlan(&node->mt_epqstate, subplanstate->plan);
 705                                 continue;
 706                         }
 707                         else
 708                                 break;
 709                 }
 710
 711                 EvalPlanQualSetSlot(&node->mt_epqstate, planSlot);
 712                 slot = planSlot;
 713
 714                 if (junkfilter != NULL)
 715                 {
 716                         /*
 717                          * extract the 'ctid' junk attribute.
 718                          */
 719                         if (operation == CMD_UPDATE || operation == CMD_DELETE)
 720                         {
 721                                 Datum           datum;
 722                                 bool            isNull;
 723
 724                                 datum = ExecGetJunkAttribute(slot, junkfilter->jf_junkAttNo,
 725                                                                                          &isNull);
 726                                 /* shouldn't ever get a null result... */
 727                                 if (isNull)
 728                                         elog(ERROR, "ctid is NULL");
 729
 730                                 tupleid = (ItemPointer) DatumGetPointer(datum);
 731                                 tuple_ctid = *tupleid;  /* be sure we don't free the ctid!! */
 732                                 tupleid = &tuple_ctid;
 733                         }
 734
 735                         /*
 736                          * apply the junkfilter if needed.
 737                          */
 738                         if (operation != CMD_DELETE)
 739                                 slot = ExecFilterJunk(junkfilter, slot);
 740                 }
 741
 742                 switch (operation)
 743                 {
 744                         case CMD_INSERT:
 745                                 slot = ExecInsert(slot, planSlot, estate);
 746                                 break;
 747                         case CMD_UPDATE:
 748                                 slot = ExecUpdate(tupleid, slot, planSlot,
 749                                                                   &node->mt_epqstate, estate);
 750                                 break;
 751                         case CMD_DELETE:
 752                                 slot = ExecDelete(tupleid, planSlot,
 753                                                                   &node->mt_epqstate, estate);
 754                                 break;
 755                         default:
 756                                 elog(ERROR, "unknown operation");
 757                                 break;
 758                 }
 759
 760                 /*
 761                  * If we got a RETURNING result, return it to caller.  We'll continue
 762                  * the work on next call.
 763                  */
 764                 if (slot)
 765                 {
 766                         estate->es_result_relation_info = NULL;
 767                         return slot;
 768                 }
 769         }
 770
 771         /* Reset es_result_relation_info before exiting */
 772         estate->es_result_relation_info = NULL;
 773
 774         /*
 775          * We're done, but fire AFTER STATEMENT triggers before exiting.
 776          */
 777         fireASTriggers(node);
 778
 779         return NULL;
 780 }
 781
 782 /* ----------------------------------------------------------------
 783  *              ExecInitModifyTable
 784  * ----------------------------------------------------------------
 785  */
 786 ModifyTableState *
 787 ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 788 {
 789         ModifyTableState *mtstate;
 790         CmdType         operation = node->operation;
 791         int                     nplans = list_length(node->plans);
 792         ResultRelInfo *resultRelInfo;
 793         TupleDesc       tupDesc;
 794         Plan       *subplan;
 795         ListCell   *l;
 796         int                     i;
 797
 798         /* check for unsupported flags */
 799         Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
 800
 801         /*
 802          * This should NOT get called during EvalPlanQual; we should have passed a
 803          * subplan tree to EvalPlanQual, instead.  Use a runtime test not just
 804          * Assert because this condition is easy to miss in testing ...
 805          */
 806         if (estate->es_epqTuple != NULL)
 807                 elog(ERROR, "ModifyTable should not be called during EvalPlanQual");
 808
 809         /*
 810          * create state structure
 811          */
 812         mtstate = makeNode(ModifyTableState);
 813         mtstate->ps.plan = (Plan *) node;
 814         mtstate->ps.state = estate;
 815         mtstate->ps.targetlist = NIL;           /* not actually used */
 816
 817         mtstate->mt_plans = (PlanState **) palloc0(sizeof(PlanState *) * nplans);
 818         mtstate->mt_nplans = nplans;
 819         mtstate->operation = operation;
 820         /* set up epqstate with dummy subplan pointer for the moment */
 821         EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, node->epqParam);
 822         mtstate->fireBSTriggers = true;
 823
 824         /* For the moment, assume our targets are exactly the global result rels */
 825
 826         /*
 827          * call ExecInitNode on each of the plans to be executed and save the
 828          * results into the array "mt_plans".  Note we *must* set
 829          * estate->es_result_relation_info correctly while we initialize each
 830          * sub-plan; ExecContextForcesOids depends on that!
 831          */
 832         estate->es_result_relation_info = estate->es_result_relations;
 833         i = 0;
 834         foreach(l, node->plans)
 835         {
 836                 subplan = (Plan *) lfirst(l);
 837                 mtstate->mt_plans[i] = ExecInitNode(subplan, estate, eflags);
 838                 estate->es_result_relation_info++;
 839                 i++;
 840         }
 841         estate->es_result_relation_info = NULL;
 842
 843         /* select first subplan */
 844         mtstate->mt_whichplan = 0;
 845         subplan = (Plan *) linitial(node->plans);
 846         EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan);
 847
 848         /*
 849          * Initialize RETURNING projections if needed.
 850          */
 851         if (node->returningLists)
 852         {
 853                 TupleTableSlot *slot;
 854                 ExprContext *econtext;
 855
 856                 /*
 857                  * Initialize result tuple slot and assign its rowtype using the first
 858                  * RETURNING list.      We assume the rest will look the same.
 859                  */
 860                 tupDesc = ExecTypeFromTL((List *) linitial(node->returningLists),
 861                                                                  false);
 862
 863                 /* Set up a slot for the output of the RETURNING projection(s) */
 864                 ExecInitResultTupleSlot(estate, &mtstate->ps);
 865                 ExecAssignResultType(&mtstate->ps, tupDesc);
 866                 slot = mtstate->ps.ps_ResultTupleSlot;
 867
 868                 /* Need an econtext too */
 869                 econtext = CreateExprContext(estate);
 870                 mtstate->ps.ps_ExprContext = econtext;
 871
 872                 /*
 873                  * Build a projection for each result rel.
 874                  */
 875                 Assert(list_length(node->returningLists) == estate->es_num_result_relations);
 876                 resultRelInfo = estate->es_result_relations;
 877                 foreach(l, node->returningLists)
 878                 {
 879                         List       *rlist = (List *) lfirst(l);
 880                         List       *rliststate;
 881
 882                         rliststate = (List *) ExecInitExpr((Expr *) rlist, &mtstate->ps);
 883                         resultRelInfo->ri_projectReturning =
 884                                 ExecBuildProjectionInfo(rliststate, econtext, slot,
 885                                                                          resultRelInfo->ri_RelationDesc->rd_att);
 886                         resultRelInfo++;
 887                 }
 888         }
 889         else
 890         {
 891                 /*
 892                  * We still must construct a dummy result tuple type, because InitPlan
 893                  * expects one (maybe should change that?).
 894                  */
 895                 tupDesc = ExecTypeFromTL(NIL, false);
 896                 ExecInitResultTupleSlot(estate, &mtstate->ps);
 897                 ExecAssignResultType(&mtstate->ps, tupDesc);
 898
 899                 mtstate->ps.ps_ExprContext = NULL;
 900         }
 901
 902         /*
 903          * If we have any secondary relations in an UPDATE or DELETE, they need to
 904          * be treated like non-locked relations in SELECT FOR UPDATE, ie, the
 905          * EvalPlanQual mechanism needs to be told about them.  Locate the
 906          * relevant ExecRowMarks.
 907          */
 908         foreach(l, node->rowMarks)
 909         {
 910                 PlanRowMark *rc = (PlanRowMark *) lfirst(l);
 911                 ExecRowMark *erm = NULL;
 912                 ListCell   *lce;
 913
 914                 Assert(IsA(rc, PlanRowMark));
 915
 916                 /* ignore "parent" rowmarks; they are irrelevant at runtime */
 917                 if (rc->isParent)
 918                         continue;
 919
 920                 foreach(lce, estate->es_rowMarks)
 921                 {
 922                         erm = (ExecRowMark *) lfirst(lce);
 923                         if (erm->rti == rc->rti)
 924                                 break;
 925                         erm = NULL;
 926                 }
 927                 if (erm == NULL)
 928                         elog(ERROR, "failed to find ExecRowMark for PlanRowMark %u",
 929                                  rc->rti);
 930
 931                 EvalPlanQualAddRowMark(&mtstate->mt_epqstate, erm);
 932         }
 933
 934         /*
 935          * Initialize the junk filter(s) if needed.  INSERT queries need a filter
 936          * if there are any junk attrs in the tlist.  UPDATE and DELETE always
 937          * need a filter, since there's always a junk 'ctid' attribute present ---
 938          * no need to look first.
 939          *
 940          * If there are multiple result relations, each one needs its own junk
 941          * filter.      Note multiple rels are only possible for UPDATE/DELETE, so we
 942          * can't be fooled by some needing a filter and some not.
 943          *
 944          * This section of code is also a convenient place to verify that the
 945          * output of an INSERT or UPDATE matches the target table(s).
 946          */
 947         {
 948                 bool            junk_filter_needed = false;
 949
 950                 switch (operation)
 951                 {
 952                         case CMD_INSERT:
 953                                 foreach(l, subplan->targetlist)
 954                                 {
 955                                         TargetEntry *tle = (TargetEntry *) lfirst(l);
 956
 957                                         if (tle->resjunk)
 958                                         {
 959                                                 junk_filter_needed = true;
 960                                                 break;
 961                                         }
 962                                 }
 963                                 break;
 964                         case CMD_UPDATE:
 965                         case CMD_DELETE:
 966                                 junk_filter_needed = true;
 967                                 break;
 968                         default:
 969                                 elog(ERROR, "unknown operation");
 970                                 break;
 971                 }
 972
 973                 if (junk_filter_needed)
 974                 {
 975                         resultRelInfo = estate->es_result_relations;
 976                         for (i = 0; i < nplans; i++)
 977                         {
 978                                 JunkFilter *j;
 979
 980                                 subplan = mtstate->mt_plans[i]->plan;
 981                                 if (operation == CMD_INSERT || operation == CMD_UPDATE)
 982                                         ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc,
 983                                                                                 subplan->targetlist);
 984
 985                                 j = ExecInitJunkFilter(subplan->targetlist,
 986                                                         resultRelInfo->ri_RelationDesc->rd_att->tdhasoid,
 987                                                                            ExecInitExtraTupleSlot(estate));
 988
 989                                 if (operation == CMD_UPDATE || operation == CMD_DELETE)
 990                                 {
 991                                         /* For UPDATE/DELETE, find the ctid junk attr now */
 992                                         j->jf_junkAttNo = ExecFindJunkAttribute(j, "ctid");
 993                                         if (!AttributeNumberIsValid(j->jf_junkAttNo))
 994                                                 elog(ERROR, "could not find junk ctid column");
 995                                 }
 996
 997                                 resultRelInfo->ri_junkFilter = j;
 998                                 resultRelInfo++;
 999                         }
1000                 }
1001                 else
1002                 {
1003                         if (operation == CMD_INSERT)
1004                                 ExecCheckPlanOutput(estate->es_result_relations->ri_RelationDesc,
1005                                                                         subplan->targetlist);
1006                 }
1007         }
1008
1009         /*
1010          * Set up a tuple table slot for use for trigger output tuples. In a plan
1011          * containing multiple ModifyTable nodes, all can share one such slot, so
1012          * we keep it in the estate.
1013          */
1014         if (estate->es_trig_tuple_slot == NULL)
1015                 estate->es_trig_tuple_slot = ExecInitExtraTupleSlot(estate);
1016
1017         return mtstate;
1018 }
1019
1020 /* ----------------------------------------------------------------
1021  *              ExecEndModifyTable
1022  *
1023  *              Shuts down the plan.
1024  *
1025  *              Returns nothing of interest.
1026  * ----------------------------------------------------------------
1027  */
1028 void
1029 ExecEndModifyTable(ModifyTableState *node)
1030 {
1031         int                     i;
1032
1033         /*
1034          * Free the exprcontext
1035          */
1036         ExecFreeExprContext(&node->ps);
1037
1038         /*
1039          * clean out the tuple table
1040          */
1041         ExecClearTuple(node->ps.ps_ResultTupleSlot);
1042
1043         /*
1044          * Terminate EPQ execution if active
1045          */
1046         EvalPlanQualEnd(&node->mt_epqstate);
1047
1048         /*
1049          * shut down subplans
1050          */
1051         for (i = 0; i < node->mt_nplans; i++)
1052                 ExecEndNode(node->mt_plans[i]);
1053 }
1054
1055 void
1056 ExecReScanModifyTable(ModifyTableState *node)
1057 {
1058         /*
1059          * Currently, we don't need to support rescan on ModifyTable nodes. The
1060          * semantics of that would be a bit debatable anyway.
1061          */
1062         elog(ERROR, "ExecReScanModifyTable is not implemented");
1063 }