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Remove dead code supporting mark/restore in SeqScan, TidScan, ValuesScan.
There seems no prospect that any of this will ever be useful, and indeed it's questionable whether some of it would work if it ever got called; it's certainly not been exercised in a very long time, if ever. So let's get rid of it, and make the comments about mark/restore in execAmi.c less wishy-washy. The mark/restore support for Result nodes is also currently dead code, but that's due to planner limitations not because it's impossible that it could be useful. So I left it in.
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11 files changed

+13
-213
lines changed

11 files changed

+13
-213
lines changed

‎src/backend/access/heap/heapam.c

Lines changed: 0 additions & 70 deletions
Original file line numberDiff line numberDiff line change
@@ -27,8 +27,6 @@
2727
* heap_multi_insert - insert multiple tuples into a relation
2828
* heap_delete - delete a tuple from a relation
2929
* heap_update - replace a tuple in a relation with another tuple
30-
* heap_markpos - mark scan position
31-
* heap_restrpos - restore position to marked location
3230
* heap_sync - sync heap, for when no WAL has been written
3331
*
3432
* NOTES
@@ -280,9 +278,6 @@ initscan(HeapScanDesc scan, ScanKey key, bool is_rescan)
280278
scan->rs_cbuf = InvalidBuffer;
281279
scan->rs_cblock = InvalidBlockNumber;
282280

283-
/* we don't have a marked position... */
284-
ItemPointerSetInvalid(&(scan->rs_mctid));
285-
286281
/* page-at-a-time fields are always invalid when not rs_inited */
287282

288283
/*
@@ -6317,71 +6312,6 @@ heap_tuple_needs_freeze(HeapTupleHeader tuple, TransactionId cutoff_xid,
63176312
return false;
63186313
}
63196314

6320-
/* ----------------
6321-
* heap_markpos - mark scan position
6322-
* ----------------
6323-
*/
6324-
void
6325-
heap_markpos(HeapScanDesc scan)
6326-
{
6327-
/* Note: no locking manipulations needed */
6328-
6329-
if (scan->rs_ctup.t_data != NULL)
6330-
{
6331-
scan->rs_mctid = scan->rs_ctup.t_self;
6332-
if (scan->rs_pageatatime)
6333-
scan->rs_mindex = scan->rs_cindex;
6334-
}
6335-
else
6336-
ItemPointerSetInvalid(&scan->rs_mctid);
6337-
}
6338-
6339-
/* ----------------
6340-
* heap_restrpos - restore position to marked location
6341-
* ----------------
6342-
*/
6343-
void
6344-
heap_restrpos(HeapScanDesc scan)
6345-
{
6346-
/* XXX no amrestrpos checking that ammarkpos called */
6347-
6348-
if (!ItemPointerIsValid(&scan->rs_mctid))
6349-
{
6350-
scan->rs_ctup.t_data = NULL;
6351-
6352-
/*
6353-
* unpin scan buffers
6354-
*/
6355-
if (BufferIsValid(scan->rs_cbuf))
6356-
ReleaseBuffer(scan->rs_cbuf);
6357-
scan->rs_cbuf = InvalidBuffer;
6358-
scan->rs_cblock = InvalidBlockNumber;
6359-
scan->rs_inited = false;
6360-
}
6361-
else
6362-
{
6363-
/*
6364-
* If we reached end of scan, rs_inited will now be false. We must
6365-
* reset it to true to keep heapgettup from doing the wrong thing.
6366-
*/
6367-
scan->rs_inited = true;
6368-
scan->rs_ctup.t_self = scan->rs_mctid;
6369-
if (scan->rs_pageatatime)
6370-
{
6371-
scan->rs_cindex = scan->rs_mindex;
6372-
heapgettup_pagemode(scan,
6373-
NoMovementScanDirection,
6374-
0, /* needn't recheck scan keys */
6375-
NULL);
6376-
}
6377-
else
6378-
heapgettup(scan,
6379-
NoMovementScanDirection,
6380-
0, /* needn't recheck scan keys */
6381-
NULL);
6382-
}
6383-
}
6384-
63856315
/*
63866316
* If 'tuple' contains any visible XID greater than latestRemovedXid,
63876317
* ratchet forwards latestRemovedXid to the greatest one found.

‎src/backend/executor/execAmi.c

Lines changed: 13 additions & 36 deletions
Original file line numberDiff line numberDiff line change
@@ -271,16 +271,20 @@ ExecReScan(PlanState *node)
271271
* ExecMarkPos
272272
*
273273
* Marks the current scan position.
274+
*
275+
* NOTE: mark/restore capability is currently needed only for plan nodes
276+
* that are the immediate inner child of a MergeJoin node. Since MergeJoin
277+
* requires sorted input, there is never any need to support mark/restore in
278+
* node types that cannot produce sorted output. There are some cases in
279+
* which a node can pass through sorted data from its child; if we don't
280+
* implement mark/restore for such a node type, the planner compensates by
281+
* inserting a Material node above that node.
274282
*/
275283
void
276284
ExecMarkPos(PlanState *node)
277285
{
278286
switch (nodeTag(node))
279287
{
280-
case T_SeqScanState:
281-
ExecSeqMarkPos((SeqScanState *) node);
282-
break;
283-
284288
case T_IndexScanState:
285289
ExecIndexMarkPos((IndexScanState *) node);
286290
break;
@@ -289,14 +293,6 @@ ExecMarkPos(PlanState *node)
289293
ExecIndexOnlyMarkPos((IndexOnlyScanState *) node);
290294
break;
291295

292-
case T_TidScanState:
293-
ExecTidMarkPos((TidScanState *) node);
294-
break;
295-
296-
case T_ValuesScanState:
297-
ExecValuesMarkPos((ValuesScanState *) node);
298-
break;
299-
300296
case T_CustomScanState:
301297
ExecCustomMarkPos((CustomScanState *) node);
302298
break;
@@ -338,10 +334,6 @@ ExecRestrPos(PlanState *node)
338334
{
339335
switch (nodeTag(node))
340336
{
341-
case T_SeqScanState:
342-
ExecSeqRestrPos((SeqScanState *) node);
343-
break;
344-
345337
case T_IndexScanState:
346338
ExecIndexRestrPos((IndexScanState *) node);
347339
break;
@@ -350,14 +342,6 @@ ExecRestrPos(PlanState *node)
350342
ExecIndexOnlyRestrPos((IndexOnlyScanState *) node);
351343
break;
352344

353-
case T_TidScanState:
354-
ExecTidRestrPos((TidScanState *) node);
355-
break;
356-
357-
case T_ValuesScanState:
358-
ExecValuesRestrPos((ValuesScanState *) node);
359-
break;
360-
361345
case T_CustomScanState:
362346
ExecCustomRestrPos((CustomScanState *) node);
363347
break;
@@ -386,14 +370,6 @@ ExecRestrPos(PlanState *node)
386370
* This is used during planning and so must accept a Path, not a Plan.
387371
* We keep it here to be adjacent to the routines above, which also must
388372
* know which plan types support mark/restore.
389-
*
390-
* XXX Ideally, all plan node types would support mark/restore, and this
391-
* wouldn't be needed. For now, this had better match the routines above.
392-
*
393-
* (However, since the only present use of mark/restore is in mergejoin,
394-
* there is no need to support mark/restore in any plan type that is not
395-
* capable of generating ordered output. So the seqscan, tidscan,
396-
* and valuesscan support is actually useless code at present.)
397373
*/
398374
bool
399375
ExecSupportsMarkRestore(Path *pathnode)
@@ -405,11 +381,8 @@ ExecSupportsMarkRestore(Path *pathnode)
405381
*/
406382
switch (pathnode->pathtype)
407383
{
408-
case T_SeqScan:
409384
case T_IndexScan:
410385
case T_IndexOnlyScan:
411-
case T_TidScan:
412-
case T_ValuesScan:
413386
case T_Material:
414387
case T_Sort:
415388
return true;
@@ -426,7 +399,11 @@ ExecSupportsMarkRestore(Path *pathnode)
426399
* Although Result supports mark/restore if it has a child plan
427400
* that does, we presently come here only for ResultPath nodes,
428401
* which represent Result plans without a child plan. So there is
429-
* nothing to recurse to and we can just say "false".
402+
* nothing to recurse to and we can just say "false". (This means
403+
* that Result's support for mark/restore is in fact dead code.
404+
* We keep it since it's not much code, and someday the planner
405+
* might be smart enough to use it. That would require making
406+
* this function smarter too, of course.)
430407
*/
431408
Assert(IsA(pathnode, ResultPath));
432409
return false;

‎src/backend/executor/nodeSeqscan.c

Lines changed: 0 additions & 38 deletions
Original file line numberDiff line numberDiff line change
@@ -19,8 +19,6 @@
1919
* ExecInitSeqScan creates and initializes a seqscan node.
2020
* ExecEndSeqScan releases any storage allocated.
2121
* ExecReScanSeqScan rescans the relation
22-
* ExecSeqMarkPos marks scan position
23-
* ExecSeqRestrPos restores scan position
2422
*/
2523
#include "postgres.h"
2624

@@ -274,39 +272,3 @@ ExecReScanSeqScan(SeqScanState *node)
274272

275273
ExecScanReScan((ScanState *) node);
276274
}
277-
278-
/* ----------------------------------------------------------------
279-
* ExecSeqMarkPos(node)
280-
*
281-
* Marks scan position.
282-
* ----------------------------------------------------------------
283-
*/
284-
void
285-
ExecSeqMarkPos(SeqScanState *node)
286-
{
287-
HeapScanDesc scan = node->ss_currentScanDesc;
288-
289-
heap_markpos(scan);
290-
}
291-
292-
/* ----------------------------------------------------------------
293-
* ExecSeqRestrPos
294-
*
295-
* Restores scan position.
296-
* ----------------------------------------------------------------
297-
*/
298-
void
299-
ExecSeqRestrPos(SeqScanState *node)
300-
{
301-
HeapScanDesc scan = node->ss_currentScanDesc;
302-
303-
/*
304-
* Clear any reference to the previously returned tuple. This is needed
305-
* because the slot is simply pointing at scan->rs_cbuf, which
306-
* heap_restrpos will change; we'd have an internally inconsistent slot if
307-
* we didn't do this.
308-
*/
309-
ExecClearTuple(node->ss_ScanTupleSlot);
310-
311-
heap_restrpos(scan);
312-
}

‎src/backend/executor/nodeTidscan.c

Lines changed: 0 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -19,8 +19,6 @@
1919
* ExecInitTidScan creates and initializes state info.
2020
* ExecReScanTidScan rescans the tid relation.
2121
* ExecEndTidScan releases all storage.
22-
* ExecTidMarkPos marks scan position.
23-
* ExecTidRestrPos restores scan position.
2422
*/
2523
#include "postgres.h"
2624

@@ -440,34 +438,6 @@ ExecEndTidScan(TidScanState *node)
440438
ExecCloseScanRelation(node->ss.ss_currentRelation);
441439
}
442440

443-
/* ----------------------------------------------------------------
444-
* ExecTidMarkPos
445-
*
446-
* Marks scan position by marking the current tid.
447-
* Returns nothing.
448-
* ----------------------------------------------------------------
449-
*/
450-
void
451-
ExecTidMarkPos(TidScanState *node)
452-
{
453-
node->tss_MarkTidPtr = node->tss_TidPtr;
454-
}
455-
456-
/* ----------------------------------------------------------------
457-
* ExecTidRestrPos
458-
*
459-
* Restores scan position by restoring the current tid.
460-
* Returns nothing.
461-
*
462-
* XXX Assumes previously marked scan position belongs to current tid
463-
* ----------------------------------------------------------------
464-
*/
465-
void
466-
ExecTidRestrPos(TidScanState *node)
467-
{
468-
node->tss_TidPtr = node->tss_MarkTidPtr;
469-
}
470-
471441
/* ----------------------------------------------------------------
472442
* ExecInitTidScan
473443
*

‎src/backend/executor/nodeValuesscan.c

Lines changed: 0 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -246,7 +246,6 @@ ExecInitValuesScan(ValuesScan *node, EState *estate, int eflags)
246246
/*
247247
* Other node-specific setup
248248
*/
249-
scanstate->marked_idx = -1;
250249
scanstate->curr_idx = -1;
251250
scanstate->array_len = list_length(node->values_lists);
252251

@@ -293,30 +292,6 @@ ExecEndValuesScan(ValuesScanState *node)
293292
ExecClearTuple(node->ss.ss_ScanTupleSlot);
294293
}
295294

296-
/* ----------------------------------------------------------------
297-
* ExecValuesMarkPos
298-
*
299-
* Marks scan position.
300-
* ----------------------------------------------------------------
301-
*/
302-
void
303-
ExecValuesMarkPos(ValuesScanState *node)
304-
{
305-
node->marked_idx = node->curr_idx;
306-
}
307-
308-
/* ----------------------------------------------------------------
309-
* ExecValuesRestrPos
310-
*
311-
* Restores scan position.
312-
* ----------------------------------------------------------------
313-
*/
314-
void
315-
ExecValuesRestrPos(ValuesScanState *node)
316-
{
317-
node->curr_idx = node->marked_idx;
318-
}
319-
320295
/* ----------------------------------------------------------------
321296
* ExecReScanValuesScan
322297
*

‎src/include/access/heapam.h

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -161,9 +161,6 @@ extern void simple_heap_delete(Relation relation, ItemPointer tid);
161161
extern void simple_heap_update(Relation relation, ItemPointer otid,
162162
HeapTuple tup);
163163

164-
extern void heap_markpos(HeapScanDesc scan);
165-
extern void heap_restrpos(HeapScanDesc scan);
166-
167164
extern void heap_sync(Relation relation);
168165

169166
/* in heap/pruneheap.c */

‎src/include/access/relscan.h

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -48,11 +48,9 @@ typedef struct HeapScanDescData
4848
BlockNumber rs_cblock; /* current block # in scan, if any */
4949
Buffer rs_cbuf; /* current buffer in scan, if any */
5050
/* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
51-
ItemPointerData rs_mctid; /* marked scan position, if any */
5251

5352
/* these fields only used in page-at-a-time mode and for bitmap scans */
5453
int rs_cindex; /* current tuple's index in vistuples */
55-
int rs_mindex; /* marked tuple's saved index */
5654
int rs_ntuples; /* number of visible tuples on page */
5755
OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */
5856
} HeapScanDescData;

‎src/include/executor/nodeSeqscan.h

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -19,8 +19,6 @@
1919
extern SeqScanState *ExecInitSeqScan(SeqScan *node, EState *estate, int eflags);
2020
extern TupleTableSlot *ExecSeqScan(SeqScanState *node);
2121
extern void ExecEndSeqScan(SeqScanState *node);
22-
extern void ExecSeqMarkPos(SeqScanState *node);
23-
extern void ExecSeqRestrPos(SeqScanState *node);
2422
extern void ExecReScanSeqScan(SeqScanState *node);
2523

2624
#endif /* NODESEQSCAN_H */

‎src/include/executor/nodeTidscan.h

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -19,8 +19,6 @@
1919
extern TidScanState *ExecInitTidScan(TidScan *node, EState *estate, int eflags);
2020
extern TupleTableSlot *ExecTidScan(TidScanState *node);
2121
extern void ExecEndTidScan(TidScanState *node);
22-
extern void ExecTidMarkPos(TidScanState *node);
23-
extern void ExecTidRestrPos(TidScanState *node);
2422
extern void ExecReScanTidScan(TidScanState *node);
2523

2624
#endif /* NODETIDSCAN_H */

‎src/include/executor/nodeValuesscan.h

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -19,8 +19,6 @@
1919
extern ValuesScanState *ExecInitValuesScan(ValuesScan *node, EState *estate, int eflags);
2020
extern TupleTableSlot *ExecValuesScan(ValuesScanState *node);
2121
extern void ExecEndValuesScan(ValuesScanState *node);
22-
extern void ExecValuesMarkPos(ValuesScanState *node);
23-
extern void ExecValuesRestrPos(ValuesScanState *node);
2422
extern void ExecReScanValuesScan(ValuesScanState *node);
2523

2624
#endif /* NODEVALUESSCAN_H */

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