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execAmi.c
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1 /*-------------------------------------------------------------------------
2  *
3  * execAmi.c
4  * miscellaneous executor access method routines
5  *
6  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * src/backend/executor/execAmi.c
10  *
11  *-------------------------------------------------------------------------
12  */
13 #include "postgres.h"
14 
15 #include "access/amapi.h"
16 #include "access/htup_details.h"
17 #include "executor/execdebug.h"
18 #include "executor/nodeAgg.h"
19 #include "executor/nodeAppend.h"
20 #include "executor/nodeBitmapAnd.h"
23 #include "executor/nodeBitmapOr.h"
24 #include "executor/nodeCtescan.h"
25 #include "executor/nodeCustom.h"
28 #include "executor/nodeGather.h"
30 #include "executor/nodeGroup.h"
31 #include "executor/nodeGroup.h"
32 #include "executor/nodeHash.h"
33 #include "executor/nodeHashjoin.h"
35 #include "executor/nodeIndexscan.h"
36 #include "executor/nodeLimit.h"
37 #include "executor/nodeLockRows.h"
38 #include "executor/nodeMaterial.h"
40 #include "executor/nodeMergejoin.h"
43 #include "executor/nodeNestloop.h"
46 #include "executor/nodeResult.h"
48 #include "executor/nodeSeqscan.h"
49 #include "executor/nodeSetOp.h"
50 #include "executor/nodeSort.h"
51 #include "executor/nodeSubplan.h"
54 #include "executor/nodeTidscan.h"
55 #include "executor/nodeUnique.h"
57 #include "executor/nodeWindowAgg.h"
59 #include "nodes/nodeFuncs.h"
60 #include "nodes/relation.h"
61 #include "utils/rel.h"
62 #include "utils/syscache.h"
63 
64 
65 static bool IndexSupportsBackwardScan(Oid indexid);
66 
67 
68 /*
69  * ExecReScan
70  * Reset a plan node so that its output can be re-scanned.
71  *
72  * Note that if the plan node has parameters that have changed value,
73  * the output might be different from last time.
74  */
75 void
77 {
78  /* If collecting timing stats, update them */
79  if (node->instrument)
80  InstrEndLoop(node->instrument);
81 
82  /*
83  * If we have changed parameters, propagate that info.
84  *
85  * Note: ExecReScanSetParamPlan() can add bits to node->chgParam,
86  * corresponding to the output param(s) that the InitPlan will update.
87  * Since we make only one pass over the list, that means that an InitPlan
88  * can depend on the output param(s) of a sibling InitPlan only if that
89  * sibling appears earlier in the list. This is workable for now given
90  * the limited ways in which one InitPlan could depend on another, but
91  * eventually we might need to work harder (or else make the planner
92  * enlarge the extParam/allParam sets to include the params of depended-on
93  * InitPlans).
94  */
95  if (node->chgParam != NULL)
96  {
97  ListCell *l;
98 
99  foreach(l, node->initPlan)
100  {
101  SubPlanState *sstate = (SubPlanState *) lfirst(l);
102  PlanState *splan = sstate->planstate;
103 
104  if (splan->plan->extParam != NULL) /* don't care about child
105  * local Params */
106  UpdateChangedParamSet(splan, node->chgParam);
107  if (splan->chgParam != NULL)
108  ExecReScanSetParamPlan(sstate, node);
109  }
110  foreach(l, node->subPlan)
111  {
112  SubPlanState *sstate = (SubPlanState *) lfirst(l);
113  PlanState *splan = sstate->planstate;
114 
115  if (splan->plan->extParam != NULL)
116  UpdateChangedParamSet(splan, node->chgParam);
117  }
118  /* Well. Now set chgParam for left/right trees. */
119  if (node->lefttree != NULL)
121  if (node->righttree != NULL)
123  }
124 
125  /* Call expression callbacks */
126  if (node->ps_ExprContext)
128 
129  /* And do node-type-specific processing */
130  switch (nodeTag(node))
131  {
132  case T_ResultState:
133  ExecReScanResult((ResultState *) node);
134  break;
135 
136  case T_ProjectSetState:
138  break;
139 
140  case T_ModifyTableState:
142  break;
143 
144  case T_AppendState:
145  ExecReScanAppend((AppendState *) node);
146  break;
147 
148  case T_MergeAppendState:
150  break;
151 
154  break;
155 
156  case T_BitmapAndState:
158  break;
159 
160  case T_BitmapOrState:
162  break;
163 
164  case T_SeqScanState:
166  break;
167 
168  case T_SampleScanState:
170  break;
171 
172  case T_GatherState:
173  ExecReScanGather((GatherState *) node);
174  break;
175 
176  case T_GatherMergeState:
178  break;
179 
180  case T_IndexScanState:
182  break;
183 
186  break;
187 
190  break;
191 
194  break;
195 
196  case T_TidScanState:
198  break;
199 
200  case T_SubqueryScanState:
202  break;
203 
204  case T_FunctionScanState:
206  break;
207 
210  break;
211 
212  case T_ValuesScanState:
214  break;
215 
216  case T_CteScanState:
218  break;
219 
222  break;
223 
226  break;
227 
228  case T_ForeignScanState:
230  break;
231 
232  case T_CustomScanState:
234  break;
235 
236  case T_NestLoopState:
238  break;
239 
240  case T_MergeJoinState:
242  break;
243 
244  case T_HashJoinState:
246  break;
247 
248  case T_MaterialState:
250  break;
251 
252  case T_SortState:
253  ExecReScanSort((SortState *) node);
254  break;
255 
256  case T_GroupState:
257  ExecReScanGroup((GroupState *) node);
258  break;
259 
260  case T_AggState:
261  ExecReScanAgg((AggState *) node);
262  break;
263 
264  case T_WindowAggState:
266  break;
267 
268  case T_UniqueState:
269  ExecReScanUnique((UniqueState *) node);
270  break;
271 
272  case T_HashState:
273  ExecReScanHash((HashState *) node);
274  break;
275 
276  case T_SetOpState:
277  ExecReScanSetOp((SetOpState *) node);
278  break;
279 
280  case T_LockRowsState:
282  break;
283 
284  case T_LimitState:
285  ExecReScanLimit((LimitState *) node);
286  break;
287 
288  default:
289  elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
290  break;
291  }
292 
293  if (node->chgParam != NULL)
294  {
295  bms_free(node->chgParam);
296  node->chgParam = NULL;
297  }
298 }
299 
300 /*
301  * ExecMarkPos
302  *
303  * Marks the current scan position.
304  *
305  * NOTE: mark/restore capability is currently needed only for plan nodes
306  * that are the immediate inner child of a MergeJoin node. Since MergeJoin
307  * requires sorted input, there is never any need to support mark/restore in
308  * node types that cannot produce sorted output. There are some cases in
309  * which a node can pass through sorted data from its child; if we don't
310  * implement mark/restore for such a node type, the planner compensates by
311  * inserting a Material node above that node.
312  */
313 void
315 {
316  switch (nodeTag(node))
317  {
318  case T_IndexScanState:
320  break;
321 
324  break;
325 
326  case T_CustomScanState:
328  break;
329 
330  case T_MaterialState:
332  break;
333 
334  case T_SortState:
335  ExecSortMarkPos((SortState *) node);
336  break;
337 
338  case T_ResultState:
339  ExecResultMarkPos((ResultState *) node);
340  break;
341 
342  default:
343  /* don't make hard error unless caller asks to restore... */
344  elog(DEBUG2, "unrecognized node type: %d", (int) nodeTag(node));
345  break;
346  }
347 }
348 
349 /*
350  * ExecRestrPos
351  *
352  * restores the scan position previously saved with ExecMarkPos()
353  *
354  * NOTE: the semantics of this are that the first ExecProcNode following
355  * the restore operation will yield the same tuple as the first one following
356  * the mark operation. It is unspecified what happens to the plan node's
357  * result TupleTableSlot. (In most cases the result slot is unchanged by
358  * a restore, but the node may choose to clear it or to load it with the
359  * restored-to tuple.) Hence the caller should discard any previously
360  * returned TupleTableSlot after doing a restore.
361  */
362 void
364 {
365  switch (nodeTag(node))
366  {
367  case T_IndexScanState:
369  break;
370 
373  break;
374 
375  case T_CustomScanState:
377  break;
378 
379  case T_MaterialState:
381  break;
382 
383  case T_SortState:
384  ExecSortRestrPos((SortState *) node);
385  break;
386 
387  case T_ResultState:
389  break;
390 
391  default:
392  elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
393  break;
394  }
395 }
396 
397 /*
398  * ExecSupportsMarkRestore - does a Path support mark/restore?
399  *
400  * This is used during planning and so must accept a Path, not a Plan.
401  * We keep it here to be adjacent to the routines above, which also must
402  * know which plan types support mark/restore.
403  */
404 bool
406 {
407  /*
408  * For consistency with the routines above, we do not examine the nodeTag
409  * but rather the pathtype, which is the Plan node type the Path would
410  * produce.
411  */
412  switch (pathnode->pathtype)
413  {
414  case T_IndexScan:
415  case T_IndexOnlyScan:
416  case T_Material:
417  case T_Sort:
418  return true;
419 
420  case T_CustomScan:
421  {
422  CustomPath *customPath = castNode(CustomPath, pathnode);
423 
424  if (customPath->flags & CUSTOMPATH_SUPPORT_MARK_RESTORE)
425  return true;
426  return false;
427  }
428  case T_Result:
429 
430  /*
431  * Result supports mark/restore iff it has a child plan that does.
432  *
433  * We have to be careful here because there is more than one Path
434  * type that can produce a Result plan node.
435  */
436  if (IsA(pathnode, ProjectionPath))
437  return ExecSupportsMarkRestore(((ProjectionPath *) pathnode)->subpath);
438  else if (IsA(pathnode, MinMaxAggPath))
439  return false; /* childless Result */
440  else
441  {
442  Assert(IsA(pathnode, ResultPath));
443  return false; /* childless Result */
444  }
445 
446  default:
447  break;
448  }
449 
450  return false;
451 }
452 
453 /*
454  * ExecSupportsBackwardScan - does a plan type support backwards scanning?
455  *
456  * Ideally, all plan types would support backwards scan, but that seems
457  * unlikely to happen soon. In some cases, a plan node passes the backwards
458  * scan down to its children, and so supports backwards scan only if its
459  * children do. Therefore, this routine must be passed a complete plan tree.
460  */
461 bool
463 {
464  if (node == NULL)
465  return false;
466 
467  /*
468  * Parallel-aware nodes return a subset of the tuples in each worker, and
469  * in general we can't expect to have enough bookkeeping state to know
470  * which ones we returned in this worker as opposed to some other worker.
471  */
472  if (node->parallel_aware)
473  return false;
474 
475  switch (nodeTag(node))
476  {
477  case T_Result:
478  if (outerPlan(node) != NULL)
479  return ExecSupportsBackwardScan(outerPlan(node));
480  else
481  return false;
482 
483  case T_Append:
484  {
485  ListCell *l;
486 
487  foreach(l, ((Append *) node)->appendplans)
488  {
489  if (!ExecSupportsBackwardScan((Plan *) lfirst(l)))
490  return false;
491  }
492  /* need not check tlist because Append doesn't evaluate it */
493  return true;
494  }
495 
496  case T_SampleScan:
497  /* Simplify life for tablesample methods by disallowing this */
498  return false;
499 
500  case T_Gather:
501  return false;
502 
503  case T_IndexScan:
504  return IndexSupportsBackwardScan(((IndexScan *) node)->indexid);
505 
506  case T_IndexOnlyScan:
507  return IndexSupportsBackwardScan(((IndexOnlyScan *) node)->indexid);
508 
509  case T_SubqueryScan:
510  return ExecSupportsBackwardScan(((SubqueryScan *) node)->subplan);
511 
512  case T_CustomScan:
513  {
514  uint32 flags = ((CustomScan *) node)->flags;
515 
517  return true;
518  }
519  return false;
520 
521  case T_SeqScan:
522  case T_TidScan:
523  case T_FunctionScan:
524  case T_ValuesScan:
525  case T_CteScan:
526  case T_Material:
527  case T_Sort:
528  return true;
529 
530  case T_LockRows:
531  case T_Limit:
532  return ExecSupportsBackwardScan(outerPlan(node));
533 
534  default:
535  return false;
536  }
537 }
538 
539 /*
540  * An IndexScan or IndexOnlyScan node supports backward scan only if the
541  * index's AM does.
542  */
543 static bool
545 {
546  bool result;
547  HeapTuple ht_idxrel;
548  Form_pg_class idxrelrec;
549  IndexAmRoutine *amroutine;
550 
551  /* Fetch the pg_class tuple of the index relation */
552  ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(indexid));
553  if (!HeapTupleIsValid(ht_idxrel))
554  elog(ERROR, "cache lookup failed for relation %u", indexid);
555  idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);
556 
557  /* Fetch the index AM's API struct */
558  amroutine = GetIndexAmRoutineByAmId(idxrelrec->relam, false);
559 
560  result = amroutine->amcanbackward;
561 
562  pfree(amroutine);
563  ReleaseSysCache(ht_idxrel);
564 
565  return result;
566 }
567 
568 /*
569  * ExecMaterializesOutput - does a plan type materialize its output?
570  *
571  * Returns true if the plan node type is one that automatically materializes
572  * its output (typically by keeping it in a tuplestore). For such plans,
573  * a rescan without any parameter change will have zero startup cost and
574  * very low per-tuple cost.
575  */
576 bool
578 {
579  switch (plantype)
580  {
581  case T_Material:
582  case T_FunctionScan:
583  case T_TableFuncScan:
584  case T_CteScan:
586  case T_WorkTableScan:
587  case T_Sort:
588  return true;
589 
590  default:
591  break;
592  }
593 
594  return false;
595 }
void ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
#define IsA(nodeptr, _type_)
Definition: nodes.h:561
void ExecReScanGroup(GroupState *node)
Definition: nodeGroup.c:245
bool ExecSupportsMarkRestore(Path *pathnode)
Definition: execAmi.c:405
void ExecMaterialRestrPos(MaterialState *node)
Definition: nodeMaterial.c:299
#define GETSTRUCT(TUP)
Definition: htup_details.h:656
#define CUSTOMPATH_SUPPORT_BACKWARD_SCAN
Definition: extensible.h:81
void ExecReScanModifyTable(ModifyTableState *node)
Instrumentation * instrument
Definition: execnodes.h:857
#define castNode(_type_, nodeptr)
Definition: nodes.h:579
#define CUSTOMPATH_SUPPORT_MARK_RESTORE
Definition: extensible.h:82
List * initPlan
Definition: execnodes.h:868
void ExecReScanMaterial(MaterialState *node)
Definition: nodeMaterial.c:322
void ExecIndexOnlyRestrPos(IndexOnlyScanState *node)
ExprContext * ps_ExprContext
Definition: execnodes.h:881
void ExecReScanLockRows(LockRowsState *node)
Definition: nodeLockRows.c:459
void ExecReScan(PlanState *node)
Definition: execAmi.c:76
void ExecReScanFunctionScan(FunctionScanState *node)
List * subPlan
Definition: execnodes.h:870
Definition: nodes.h:48
void ExecReScanIndexOnlyScan(IndexOnlyScanState *node)
uint32 flags
Definition: relation.h:1247
Definition: nodes.h:75
void ExecReScanLimit(LimitState *node)
Definition: nodeLimit.c:401
void ExecReScanWorkTableScan(WorkTableScanState *node)
struct PlanState * righttree
Definition: execnodes.h:867
unsigned int Oid
Definition: postgres_ext.h:31
NodeTag
Definition: nodes.h:26
void ExecReScanResult(ResultState *node)
Definition: nodeResult.c:265
void ExecResultRestrPos(ResultState *node)
Definition: nodeResult.c:162
void ExecReScanSetOp(SetOpState *node)
Definition: nodeSetOp.c:597
static bool IndexSupportsBackwardScan(Oid indexid)
Definition: execAmi.c:544
void ExecReScanSort(SortState *node)
Definition: nodeSort.c:306
void ExecReScanForeignScan(ForeignScanState *node)
struct PlanState * lefttree
Definition: execnodes.h:866
void InstrEndLoop(Instrumentation *instr)
Definition: instrument.c:114
NodeTag pathtype
Definition: relation.h:1040
void ExecCustomRestrPos(CustomScanState *node)
Definition: nodeCustom.c:158
void ExecRestrPos(PlanState *node)
Definition: execAmi.c:363
void ExecReScanHash(HashState *node)
Definition: nodeHash.c:1270
void pfree(void *pointer)
Definition: mcxt.c:949
void ExecIndexOnlyMarkPos(IndexOnlyScanState *node)
void ExecReScanProjectSet(ProjectSetState *node)
Definition: nodes.h:45
#define ObjectIdGetDatum(X)
Definition: postgres.h:513
#define ERROR
Definition: elog.h:43
struct PlanState * planstate
Definition: execnodes.h:758
void ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
Definition: nodeSubplan.c:1092
IndexAmRoutine * GetIndexAmRoutineByAmId(Oid amoid, bool noerror)
Definition: amapi.c:56
#define DEBUG2
Definition: elog.h:24
void ExecSortMarkPos(SortState *node)
Definition: nodeSort.c:273
void ExecReScanBitmapIndexScan(BitmapIndexScanState *node)
bool amcanbackward
Definition: amapi.h:175
void ExecIndexMarkPos(IndexScanState *node)
void ExecReScanUnique(UniqueState *node)
Definition: nodeUnique.c:190
void ExecReScanIndexScan(IndexScanState *node)
void ExecReScanGatherMerge(GatherMergeState *node)
bool parallel_aware
Definition: plannodes.h:137
void ExecReScanMergeAppend(MergeAppendState *node)
unsigned int uint32
Definition: c.h:258
void ExecReScanNestLoop(NestLoopState *node)
Definition: nodeNestloop.c:396
static SPIPlanPtr splan
Definition: regress.c:449
Bitmapset * chgParam
Definition: execnodes.h:875
#define outerPlan(node)
Definition: plannodes.h:174
void ExecReScanGather(GatherState *node)
Definition: nodeGather.c:418
void ExecReScanNamedTuplestoreScan(NamedTuplestoreScanState *node)
HeapTuple SearchSysCache1(int cacheId, Datum key1)
Definition: syscache.c:1112
void ExecReScanAppend(AppendState *node)
Definition: nodeAppend.c:279
void ReleaseSysCache(HeapTuple tuple)
Definition: syscache.c:1160
bool ExecSupportsBackwardScan(Plan *node)
Definition: execAmi.c:462
void ExecReScanSubqueryScan(SubqueryScanState *node)
void ExecCustomMarkPos(CustomScanState *node)
Definition: nodeCustom.c:147
Plan * plan
Definition: execnodes.h:847
void ExecMarkPos(PlanState *node)
Definition: execAmi.c:314
void ExecReScanBitmapOr(BitmapOrState *node)
Definition: nodeBitmapOr.c:219
void ExecReScanRecursiveUnion(RecursiveUnionState *node)
void UpdateChangedParamSet(PlanState *node, Bitmapset *newchg)
Definition: execUtils.c:676
void bms_free(Bitmapset *a)
Definition: bitmapset.c:201
#define HeapTupleIsValid(tuple)
Definition: htup.h:77
#define Assert(condition)
Definition: c.h:681
#define lfirst(lc)
Definition: pg_list.h:106
void ExecReScanBitmapAnd(BitmapAndState *node)
void ExecReScanAgg(AggState *node)
Definition: nodeAgg.c:3981
void ExecSortRestrPos(SortState *node)
Definition: nodeSort.c:291
void ExecResultMarkPos(ResultState *node)
Definition: nodeResult.c:147
Bitmapset * extParam
Definition: plannodes.h:162
void ReScanExprContext(ExprContext *econtext)
Definition: execUtils.c:381
void ExecIndexRestrPos(IndexScanState *node)
#define nodeTag(nodeptr)
Definition: nodes.h:515
void ExecReScanValuesScan(ValuesScanState *node)
FormData_pg_class * Form_pg_class
Definition: pg_class.h:95
Definition: nodes.h:80
void ExecReScanSampleScan(SampleScanState *node)
void ExecReScanCteScan(CteScanState *node)
Definition: nodeCtescan.c:310
void ExecMaterialMarkPos(MaterialState *node)
Definition: nodeMaterial.c:271
void ExecReScanWindowAgg(WindowAggState *node)
bool ExecMaterializesOutput(NodeTag plantype)
Definition: execAmi.c:577
#define elog
Definition: elog.h:219
void ExecReScanTidScan(TidScanState *node)
Definition: nodeTidscan.c:463
void ExecReScanMergeJoin(MergeJoinState *node)
void ExecReScanCustomScan(CustomScanState *node)
Definition: nodeCustom.c:140
void ExecReScanTableFuncScan(TableFuncScanState *node)
Datum subpath(PG_FUNCTION_ARGS)
Definition: ltree_op.c:234
void ExecReScanSeqScan(SeqScanState *node)
Definition: nodeSeqscan.c:271
Definition: nodes.h:85
void ExecReScanHashJoin(HashJoinState *node)
Definition: nodeHashjoin.c:898