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Commitcefcbbf

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committed
Push the responsibility for handling ignore_killed_tuples down into
_bt_checkkeys(), instead of checking it in the top-level nbtree.c routinesas formerly. This saves a little bit of loop overhead, but more importantlyit lets us skip performing the index key comparisons for dead tuples.
1 parentf1b059a commitcefcbbf

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4 files changed

+72
-72
lines changed

4 files changed

+72
-72
lines changed

‎src/backend/access/nbtree/nbtree.c

Lines changed: 3 additions & 38 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
* Portions Copyright (c) 1994, Regents of the University of California
1313
*
1414
* IDENTIFICATION
15-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.134 2005/11/22 18:17:06 momjian Exp $
15+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.135 2005/12/07 19:37:53 tgl Exp $
1616
*
1717
*-------------------------------------------------------------------------
1818
*/
@@ -288,21 +288,6 @@ btgettuple(PG_FUNCTION_ARGS)
288288
else
289289
res=_bt_first(scan,dir);
290290

291-
/*
292-
* Skip killed tuples if asked to.
293-
*/
294-
if (scan->ignore_killed_tuples)
295-
{
296-
while (res)
297-
{
298-
offnum=ItemPointerGetOffsetNumber(&(scan->currentItemData));
299-
page=BufferGetPage(so->btso_curbuf);
300-
if (!ItemIdDeleted(PageGetItemId(page,offnum)))
301-
break;
302-
res=_bt_next(scan,dir);
303-
}
304-
}
305-
306291
/*
307292
* Save heap TID to use it in _bt_restscan. Then release the read lock on
308293
* the buffer so that we aren't blocking other backends.
@@ -353,25 +338,6 @@ btgetmulti(PG_FUNCTION_ARGS)
353338
res=_bt_next(scan,ForwardScanDirection);
354339
else
355340
res=_bt_first(scan,ForwardScanDirection);
356-
357-
/*
358-
* Skip killed tuples if asked to.
359-
*/
360-
if (scan->ignore_killed_tuples)
361-
{
362-
while (res)
363-
{
364-
Pagepage;
365-
OffsetNumberoffnum;
366-
367-
offnum=ItemPointerGetOffsetNumber(&(scan->currentItemData));
368-
page=BufferGetPage(so->btso_curbuf);
369-
if (!ItemIdDeleted(PageGetItemId(page,offnum)))
370-
break;
371-
res=_bt_next(scan,ForwardScanDirection);
372-
}
373-
}
374-
375341
if (!res)
376342
break;
377343
/* Save tuple ID, and continue scanning */
@@ -385,9 +351,8 @@ btgetmulti(PG_FUNCTION_ARGS)
385351
*/
386352
if (res)
387353
{
388-
((BTScanOpaque)scan->opaque)->curHeapIptr=scan->xs_ctup.t_self;
389-
LockBuffer(((BTScanOpaque)scan->opaque)->btso_curbuf,
390-
BUFFER_LOCK_UNLOCK);
354+
so->curHeapIptr=scan->xs_ctup.t_self;
355+
LockBuffer(so->btso_curbuf,BUFFER_LOCK_UNLOCK);
391356
}
392357

393358
*returned_tids=ntids;

‎src/backend/access/nbtree/nbtsearch.c

Lines changed: 4 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.98 2005/12/0718:03:48 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.99 2005/12/0719:37:53 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -423,8 +423,6 @@ _bt_next(IndexScanDesc scan, ScanDirection dir)
423423
Pagepage;
424424
OffsetNumberoffnum;
425425
ItemPointercurrent;
426-
BTItembtitem;
427-
IndexTupleitup;
428426
BTScanOpaqueso;
429427
boolcontinuescan;
430428

@@ -445,13 +443,10 @@ _bt_next(IndexScanDesc scan, ScanDirection dir)
445443
/* current is the next candidate tuple to return */
446444
offnum=ItemPointerGetOffsetNumber(current);
447445
page=BufferGetPage(buf);
448-
btitem= (BTItem)PageGetItem(page,PageGetItemId(page,offnum));
449-
itup=&btitem->bti_itup;
450446

451-
if (_bt_checkkeys(scan,itup,dir,&continuescan))
447+
if (_bt_checkkeys(scan,page,offnum,dir,&continuescan))
452448
{
453449
/* tuple passes all scan key conditions, so return it */
454-
scan->xs_ctup.t_self=itup->t_tid;
455450
return true;
456451
}
457452

@@ -485,8 +480,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
485480
Pagepage;
486481
BTStackstack;
487482
OffsetNumberoffnum;
488-
BTItembtitem;
489-
IndexTupleitup;
490483
ItemPointercurrent;
491484
BlockNumberblkno;
492485
StrategyNumberstrat;
@@ -848,14 +841,11 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
848841
/* okay, current item pointer for the scan is right */
849842
offnum=ItemPointerGetOffsetNumber(current);
850843
page=BufferGetPage(buf);
851-
btitem= (BTItem)PageGetItem(page,PageGetItemId(page,offnum));
852-
itup=&btitem->bti_itup;
853844

854845
/* is the first item actually acceptable? */
855-
if (_bt_checkkeys(scan,itup,dir,&continuescan))
846+
if (_bt_checkkeys(scan,page,offnum,dir,&continuescan))
856847
{
857848
/* yes, return it */
858-
scan->xs_ctup.t_self=itup->t_tid;
859849
res= true;
860850
}
861851
elseif (continuescan)
@@ -1215,8 +1205,6 @@ _bt_endpoint(IndexScanDesc scan, ScanDirection dir)
12151205
OffsetNumbermaxoff;
12161206
OffsetNumberstart;
12171207
BlockNumberblkno;
1218-
BTItembtitem;
1219-
IndexTupleitup;
12201208
BTScanOpaqueso;
12211209
boolres;
12221210
boolcontinuescan;
@@ -1284,16 +1272,12 @@ _bt_endpoint(IndexScanDesc scan, ScanDirection dir)
12841272
page=BufferGetPage(buf);
12851273
}
12861274

1287-
btitem= (BTItem)PageGetItem(page,PageGetItemId(page,start));
1288-
itup=&(btitem->bti_itup);
1289-
12901275
/*
12911276
* Okay, we are on the first or last tuple. Does it pass all the quals?
12921277
*/
1293-
if (_bt_checkkeys(scan,itup,dir,&continuescan))
1278+
if (_bt_checkkeys(scan,page,start,dir,&continuescan))
12941279
{
12951280
/* yes, return it */
1296-
scan->xs_ctup.t_self=itup->t_tid;
12971281
res= true;
12981282
}
12991283
elseif (continuescan)

‎src/backend/access/nbtree/nbtutils.c

Lines changed: 61 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.66 2005/11/22 18:17:06 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.67 2005/12/07 19:37:53 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -477,30 +477,77 @@ _bt_preprocess_keys(IndexScanDesc scan)
477477
/*
478478
* Test whether an indextuple satisfies all the scankey conditions.
479479
*
480+
* If so, copy its TID into scan->xs_ctup.t_self, and return TRUE.
481+
* If not, return FALSE (xs_ctup is not changed).
482+
*
480483
* If the tuple fails to pass the qual, we also determine whether there's
481484
* any need to continue the scan beyond this tuple, and set *continuescan
482485
* accordingly. See comments for _bt_preprocess_keys(), above, about how
483486
* this is done.
487+
*
488+
* scan: index scan descriptor
489+
* page: buffer page containing index tuple
490+
* offnum: offset number of index tuple (must be a valid item!)
491+
* dir: direction we are scanning in
492+
* continuescan: output parameter (will be set correctly in all cases)
484493
*/
485494
bool
486-
_bt_checkkeys(IndexScanDescscan,IndexTupletuple,
495+
_bt_checkkeys(IndexScanDescscan,
496+
Pagepage,OffsetNumberoffnum,
487497
ScanDirectiondir,bool*continuescan)
488498
{
489-
BTScanOpaqueso= (BTScanOpaque)scan->opaque;
490-
intkeysz=so->numberOfKeys;
491-
intikey;
499+
ItemIdiid=PageGetItemId(page,offnum);
500+
booltuple_valid;
501+
BTItembtitem;
502+
IndexTupletuple;
492503
TupleDesctupdesc;
504+
BTScanOpaqueso;
505+
intkeysz;
506+
intikey;
493507
ScanKeykey;
494508

495-
*continuescan= true;
509+
*continuescan= true;/* default assumption */
510+
511+
/*
512+
* If the scan specifies not to return killed tuples, then we treat
513+
* a killed tuple as not passing the qual. Most of the time, it's a
514+
* win to not bother examining the tuple's index keys, but just return
515+
* immediately with continuescan = true to proceed to the next tuple.
516+
* However, if this is the last tuple on the page, we should check
517+
* the index keys to prevent uselessly advancing to the next page.
518+
*/
519+
if (scan->ignore_killed_tuples&&ItemIdDeleted(iid))
520+
{
521+
/* return immediately if there are more tuples on the page */
522+
if (ScanDirectionIsForward(dir))
523+
{
524+
if (offnum<PageGetMaxOffsetNumber(page))
525+
return false;
526+
}
527+
else
528+
{
529+
BTPageOpaqueopaque= (BTPageOpaque)PageGetSpecialPointer(page);
530+
531+
if (offnum>P_FIRSTDATAKEY(opaque))
532+
return false;
533+
}
534+
/*
535+
* OK, we want to check the keys, but we'll return FALSE even
536+
* if the tuple passes the key tests.
537+
*/
538+
tuple_valid= false;
539+
}
540+
else
541+
tuple_valid= true;
496542

497-
/* If no keys, always scan the whole index */
498-
if (keysz==0)
499-
return true;
543+
btitem= (BTItem)PageGetItem(page,iid);
544+
tuple=&btitem->bti_itup;
500545

501546
IncrIndexProcessed();
502547

503548
tupdesc=RelationGetDescr(scan->indexRelation);
549+
so= (BTScanOpaque)scan->opaque;
550+
keysz=so->numberOfKeys;
504551

505552
for (key=so->keyData,ikey=0;ikey<keysz;key++,ikey++)
506553
{
@@ -592,6 +639,9 @@ _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple,
592639
}
593640
}
594641

595-
/* If we get here, the tuple passes all quals. */
596-
return true;
642+
/* If we get here, the tuple passes all index quals. */
643+
if (tuple_valid)
644+
scan->xs_ctup.t_self=tuple->t_tid;
645+
646+
returntuple_valid;
597647
}

‎src/include/access/nbtree.h

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.88 2005/11/06 19:29:01 tgl Exp $
10+
* $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.89 2005/12/07 19:37:53 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -467,8 +467,9 @@ extern ScanKey _bt_mkscankey_nodata(Relation rel);
467467
externvoid_bt_freeskey(ScanKeyskey);
468468
externvoid_bt_freestack(BTStackstack);
469469
externvoid_bt_preprocess_keys(IndexScanDescscan);
470-
externbool_bt_checkkeys(IndexScanDescscan,IndexTupletuple,
471-
ScanDirectiondir,bool*continuescan);
470+
externbool_bt_checkkeys(IndexScanDescscan,
471+
Pagepage,OffsetNumberoffnum,
472+
ScanDirectiondir,bool*continuescan);
472473
externBTItem_bt_formitem(IndexTupleitup);
473474

474475
/*

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