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Commitec498cd

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committed
Create new routines systable_beginscan_ordered, systable_getnext_ordered,
systable_endscan_ordered that have API similar to systable_beginscan etc(in particular, the passed-in scankeys have heap not index attnums),but guarantee ordered output, unlike the existing functions. For the momentthese are just very thin wrappers around index_beginscan/index_getnext/etc.Someday they might need to get smarter; but for now this is just a coderefactoring exercise to reduce the number of direct callers of index_getnext,in preparation for changing that function's API.In passing, remove index_getnext_indexitem, which has been dead code forquite some time, and will have even less use than that in the presenceof run-time-lossy indexes.
1 parent0083280 commitec498cd

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9 files changed

+168
-124
lines changed

9 files changed

+168
-124
lines changed

‎src/backend/access/heap/tuptoaster.c

Lines changed: 23 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.85 2008/03/26 21:10:37 alvherre Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.86 2008/04/12 23:14:21 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -1184,7 +1184,9 @@ toast_save_datum(Relation rel, Datum value,
11841184
toast_pointer.va_extsize=data_todo;
11851185
}
11861186

1187-
toast_pointer.va_valueid=GetNewOidWithIndex(toastrel,toastidx);
1187+
toast_pointer.va_valueid=GetNewOidWithIndex(toastrel,
1188+
RelationGetRelid(toastidx),
1189+
(AttrNumber)1);
11881190
toast_pointer.va_toastrelid=rel->rd_rel->reltoastrelid;
11891191

11901192
/*
@@ -1273,7 +1275,7 @@ toast_delete_datum(Relation rel, Datum value)
12731275
Relationtoastrel;
12741276
Relationtoastidx;
12751277
ScanKeyDatatoastkey;
1276-
IndexScanDesctoastscan;
1278+
SysScanDesctoastscan;
12771279
HeapTupletoasttup;
12781280

12791281
if (!VARATT_IS_EXTERNAL(attr))
@@ -1289,20 +1291,21 @@ toast_delete_datum(Relation rel, Datum value)
12891291
toastidx=index_open(toastrel->rd_rel->reltoastidxid,RowExclusiveLock);
12901292

12911293
/*
1292-
* Setup a scan key to fetch from the index by va_valueid (we don't
1293-
* particularly care whether we see them in sequence or not)
1294+
* Setup a scan key to find chunks with matching va_valueid
12941295
*/
12951296
ScanKeyInit(&toastkey,
12961297
(AttrNumber)1,
12971298
BTEqualStrategyNumber,F_OIDEQ,
12981299
ObjectIdGetDatum(toast_pointer.va_valueid));
12991300

13001301
/*
1301-
* Find the chunks by index
1302+
* Find all the chunks. (We don't actually care whether we see them in
1303+
* sequence or not, but since we've already locked the index we might
1304+
* as well use systable_beginscan_ordered.)
13021305
*/
1303-
toastscan=index_beginscan(toastrel,toastidx,
1304-
SnapshotToast,1,&toastkey);
1305-
while ((toasttup=index_getnext(toastscan,ForwardScanDirection))!=NULL)
1306+
toastscan=systable_beginscan_ordered(toastrel,toastidx,
1307+
SnapshotToast,1,&toastkey);
1308+
while ((toasttup=systable_getnext_ordered(toastscan,ForwardScanDirection))!=NULL)
13061309
{
13071310
/*
13081311
* Have a chunk, delete it
@@ -1313,7 +1316,7 @@ toast_delete_datum(Relation rel, Datum value)
13131316
/*
13141317
* End scan and close relations
13151318
*/
1316-
index_endscan(toastscan);
1319+
systable_endscan_ordered(toastscan);
13171320
index_close(toastidx,RowExclusiveLock);
13181321
heap_close(toastrel,RowExclusiveLock);
13191322
}
@@ -1332,7 +1335,7 @@ toast_fetch_datum(struct varlena * attr)
13321335
Relationtoastrel;
13331336
Relationtoastidx;
13341337
ScanKeyDatatoastkey;
1335-
IndexScanDesctoastscan;
1338+
SysScanDesctoastscan;
13361339
HeapTuplettup;
13371340
TupleDesctoasttupDesc;
13381341
structvarlena*result;
@@ -1383,9 +1386,9 @@ toast_fetch_datum(struct varlena * attr)
13831386
*/
13841387
nextidx=0;
13851388

1386-
toastscan=index_beginscan(toastrel,toastidx,
1387-
SnapshotToast,1,&toastkey);
1388-
while ((ttup=index_getnext(toastscan,ForwardScanDirection))!=NULL)
1389+
toastscan=systable_beginscan_ordered(toastrel,toastidx,
1390+
SnapshotToast,1,&toastkey);
1391+
while ((ttup=systable_getnext_ordered(toastscan,ForwardScanDirection))!=NULL)
13891392
{
13901393
/*
13911394
* Have a chunk, extract the sequence number and the data
@@ -1464,7 +1467,7 @@ toast_fetch_datum(struct varlena * attr)
14641467
/*
14651468
* End scan and close relations
14661469
*/
1467-
index_endscan(toastscan);
1470+
systable_endscan_ordered(toastscan);
14681471
index_close(toastidx,AccessShareLock);
14691472
heap_close(toastrel,AccessShareLock);
14701473

@@ -1485,7 +1488,7 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
14851488
Relationtoastidx;
14861489
ScanKeyDatatoastkey[3];
14871490
intnscankeys;
1488-
IndexScanDesctoastscan;
1491+
SysScanDesctoastscan;
14891492
HeapTuplettup;
14901493
TupleDesctoasttupDesc;
14911494
structvarlena*result;
@@ -1592,9 +1595,9 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
15921595
* The index is on (valueid, chunkidx) so they will come in order
15931596
*/
15941597
nextidx=startchunk;
1595-
toastscan=index_beginscan(toastrel,toastidx,
1596-
SnapshotToast,nscankeys,toastkey);
1597-
while ((ttup=index_getnext(toastscan,ForwardScanDirection))!=NULL)
1598+
toastscan=systable_beginscan_ordered(toastrel,toastidx,
1599+
SnapshotToast,nscankeys,toastkey);
1600+
while ((ttup=systable_getnext_ordered(toastscan,ForwardScanDirection))!=NULL)
15981601
{
15991602
/*
16001603
* Have a chunk, extract the sequence number and the data
@@ -1681,7 +1684,7 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
16811684
/*
16821685
* End scan and close relations
16831686
*/
1684-
index_endscan(toastscan);
1687+
systable_endscan_ordered(toastscan);
16851688
index_close(toastidx,AccessShareLock);
16861689
heap_close(toastrel,AccessShareLock);
16871690

‎src/backend/access/index/genam.c

Lines changed: 85 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.66 2008/04/10 22:25:25 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.67 2008/04/12 23:14:21 tgl Exp $
1212
*
1313
* NOTES
1414
* many of the old access method routines have been turned into
@@ -258,3 +258,87 @@ systable_endscan(SysScanDesc sysscan)
258258

259259
pfree(sysscan);
260260
}
261+
262+
263+
/*
264+
* systable_beginscan_ordered --- set up for ordered catalog scan
265+
*
266+
* These routines have essentially the same API as systable_beginscan etc,
267+
* except that they guarantee to return multiple matching tuples in
268+
* index order. Also, for largely historical reasons, the index to use
269+
* is opened and locked by the caller, not here.
270+
*
271+
* Currently we do not support non-index-based scans here. (In principle
272+
* we could do a heapscan and sort, but the uses are in places that
273+
* probably don't need to still work with corrupted catalog indexes.)
274+
* For the moment, therefore, these functions are merely the thinnest of
275+
* wrappers around index_beginscan/index_getnext. The main reason for their
276+
* existence is to centralize possible future support of lossy operators
277+
* in catalog scans.
278+
*/
279+
SysScanDesc
280+
systable_beginscan_ordered(RelationheapRelation,
281+
RelationindexRelation,
282+
Snapshotsnapshot,
283+
intnkeys,ScanKeykey)
284+
{
285+
SysScanDescsysscan;
286+
inti;
287+
288+
/* REINDEX can probably be a hard error here ... */
289+
if (ReindexIsProcessingIndex(RelationGetRelid(indexRelation)))
290+
elog(ERROR,"cannot do ordered scan on index \"%s\", because it is the current REINDEX target",
291+
RelationGetRelationName(indexRelation));
292+
/* ... but we only throw a warning about violating IgnoreSystemIndexes */
293+
if (IgnoreSystemIndexes)
294+
elog(WARNING,"using index \"%s\" despite IgnoreSystemIndexes",
295+
RelationGetRelationName(indexRelation));
296+
297+
sysscan= (SysScanDesc)palloc(sizeof(SysScanDescData));
298+
299+
sysscan->heap_rel=heapRelation;
300+
sysscan->irel=indexRelation;
301+
302+
/*
303+
* Change attribute numbers to be index column numbers.
304+
*
305+
* This code could be generalized to search for the index key numbers
306+
* to substitute, but for now there's no need.
307+
*/
308+
for (i=0;i<nkeys;i++)
309+
{
310+
Assert(key[i].sk_attno==indexRelation->rd_index->indkey.values[i]);
311+
key[i].sk_attno=i+1;
312+
}
313+
314+
sysscan->iscan=index_beginscan(heapRelation,indexRelation,
315+
snapshot,nkeys,key);
316+
sysscan->scan=NULL;
317+
318+
returnsysscan;
319+
}
320+
321+
/*
322+
* systable_getnext_ordered --- get next tuple in an ordered catalog scan
323+
*/
324+
HeapTuple
325+
systable_getnext_ordered(SysScanDescsysscan,ScanDirectiondirection)
326+
{
327+
HeapTuplehtup;
328+
329+
Assert(sysscan->irel);
330+
htup=index_getnext(sysscan->iscan,direction);
331+
332+
returnhtup;
333+
}
334+
335+
/*
336+
* systable_endscan_ordered --- close scan, release resources
337+
*/
338+
void
339+
systable_endscan_ordered(SysScanDescsysscan)
340+
{
341+
Assert(sysscan->irel);
342+
index_endscan(sysscan->iscan);
343+
pfree(sysscan);
344+
}

‎src/backend/access/index/indexam.c

Lines changed: 2 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.105 2008/04/10 22:25:25 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.106 2008/04/12 23:14:21 tgl Exp $
1212
*
1313
* INTERFACE ROUTINES
1414
*index_open- open an index relation by relation OID
@@ -206,12 +206,7 @@ index_insert(Relation indexRelation,
206206
/*
207207
* index_beginscan - start a scan of an index with amgettuple
208208
*
209-
* Note: heapRelation may be NULL if there is no intention of calling
210-
* index_getnext on this scan; index_getnext_indexitem will not use the
211-
* heapRelation link (nor the snapshot). However, the caller had better
212-
* be holding some kind of lock on the heap relation in any case, to ensure
213-
* no one deletes it (or the index) out from under us.Caller must also
214-
* be holding a lock on the index.
209+
* Caller must be holding suitable locks on the heap and the index.
215210
*/
216211
IndexScanDesc
217212
index_beginscan(RelationheapRelation,
@@ -634,45 +629,6 @@ index_getnext(IndexScanDesc scan, ScanDirection direction)
634629
returnNULL;/* failure exit */
635630
}
636631

637-
/* ----------------
638-
*index_getnext_indexitem - get the next index tuple from a scan
639-
*
640-
* Finds the next index tuple satisfying the scan keys. Note that the
641-
* corresponding heap tuple is not accessed, and thus no time qual (snapshot)
642-
* check is done, other than the index AM's internal check for killed tuples
643-
* (which most callers of this routine will probably want to suppress by
644-
* setting scan->ignore_killed_tuples = false).
645-
*
646-
* On success (TRUE return), the heap TID of the found index entry is in
647-
* scan->xs_ctup.t_self. scan->xs_cbuf is untouched.
648-
* ----------------
649-
*/
650-
bool
651-
index_getnext_indexitem(IndexScanDescscan,
652-
ScanDirectiondirection)
653-
{
654-
FmgrInfo*procedure;
655-
boolfound;
656-
657-
SCAN_CHECKS;
658-
GET_SCAN_PROCEDURE(amgettuple);
659-
660-
/* just make sure this is false... */
661-
scan->kill_prior_tuple= false;
662-
663-
/*
664-
* have the am's gettuple proc do all the work.
665-
*/
666-
found=DatumGetBool(FunctionCall2(procedure,
667-
PointerGetDatum(scan),
668-
Int32GetDatum(direction)));
669-
670-
if (found)
671-
pgstat_count_index_tuples(scan->indexRelation,1);
672-
673-
returnfound;
674-
}
675-
676632
/* ----------------
677633
*index_getbitmap - get all tuples at once from an index scan
678634
*

‎src/backend/catalog/catalog.c

Lines changed: 11 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/catalog/catalog.c,v 1.74 2008/03/26 16:20:46 alvherre Exp $
13+
* $PostgreSQL: pgsql/src/backend/catalog/catalog.c,v 1.75 2008/04/12 23:14:21 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -312,9 +312,7 @@ IsSharedRelation(Oid relationId)
312312
Oid
313313
GetNewOid(Relationrelation)
314314
{
315-
OidnewOid;
316315
OidoidIndex;
317-
Relationindexrel;
318316

319317
/* If relation doesn't have OIDs at all, caller is confused */
320318
Assert(relation->rd_rel->relhasoids);
@@ -342,11 +340,7 @@ GetNewOid(Relation relation)
342340
}
343341

344342
/* Otherwise, use the index to find a nonconflicting OID */
345-
indexrel=index_open(oidIndex,AccessShareLock);
346-
newOid=GetNewOidWithIndex(relation,indexrel);
347-
index_close(indexrel,AccessShareLock);
348-
349-
returnnewOid;
343+
returnGetNewOidWithIndex(relation,oidIndex,ObjectIdAttributeNumber);
350344
}
351345

352346
/*
@@ -357,16 +351,17 @@ GetNewOid(Relation relation)
357351
* an index that will not be recognized by RelationGetOidIndex: TOAST tables
358352
* and pg_largeobject have indexes that are usable, but have multiple columns
359353
* and are on ordinary columns rather than a true OID column. This code
360-
* will work anyway, so long as the OID is the index's first column.
354+
* will work anyway, so long as the OID is the index's first column. The
355+
* caller must pass in the actual heap attnum of the OID column, however.
361356
*
362357
* Caller must have a suitable lock on the relation.
363358
*/
364359
Oid
365-
GetNewOidWithIndex(Relationrelation,Relationindexrel)
360+
GetNewOidWithIndex(Relationrelation,OidindexId,AttrNumberoidcolumn)
366361
{
367362
OidnewOid;
368363
SnapshotDataSnapshotDirty;
369-
IndexScanDescscan;
364+
SysScanDescscan;
370365
ScanKeyDatakey;
371366
boolcollides;
372367

@@ -380,17 +375,17 @@ GetNewOidWithIndex(Relation relation, Relation indexrel)
380375
newOid=GetNewObjectId();
381376

382377
ScanKeyInit(&key,
383-
(AttrNumber)1,
378+
oidcolumn,
384379
BTEqualStrategyNumber,F_OIDEQ,
385380
ObjectIdGetDatum(newOid));
386381

387382
/* see notes above about using SnapshotDirty */
388-
scan=index_beginscan(relation,indexrel,
389-
&SnapshotDirty,1,&key);
383+
scan=systable_beginscan(relation,indexId, true,
384+
&SnapshotDirty,1,&key);
390385

391-
collides=HeapTupleIsValid(index_getnext(scan,ForwardScanDirection));
386+
collides=HeapTupleIsValid(systable_getnext(scan));
392387

393-
index_endscan(scan);
388+
systable_endscan(scan);
394389
}while (collides);
395390

396391
returnnewOid;

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