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Minor performance improvement in MultiRecordFreeSpace.

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This commit is contained in:
Tom Lane
2001-07-19 21:25:37 +00:00
parent 7d4d5c00f0
commit 8a59f336bb
1 changed files with 16 additions and 2 deletions
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18
src/backend/storage/freespace/freespace.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.3 2001/07/02 20:50:46 tgl Exp $ * $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.4 2001/07/19 21:25:37 tgl Exp $
* *
* *
* NOTES: * NOTES:
@ -419,9 +419,23 @@ MultiRecordFreeSpace(RelFileNode *rel,
* *
* XXX we could probably be smarter about this than doing it * XXX we could probably be smarter about this than doing it
* completely separately for each one. FIXME later. * completely separately for each one. FIXME later.
*
* One thing we can do is short-circuit the process entirely if
* a page (a) has too little free space to be recorded, and (b)
* is within the minPage..maxPage range --- then we deleted any
* old entry above, and we aren't going to make a new one.
* This is particularly useful since in most cases, all the passed
* pages will in fact be in the minPage..maxPage range.
*/ */
for (i = 0; i < nPages; i++) for (i = 0; i < nPages; i++)
fsm_record_free_space(fsmrel, pages[i], spaceAvail[i]); {
BlockNumber page = pages[i];
Size avail = spaceAvail[i];
if (avail >= fsmrel->threshold ||
page < minPage || page > maxPage)
fsm_record_free_space(fsmrel, page, avail);
}
} }
SpinRelease(FreeSpaceLock); SpinRelease(FreeSpaceLock);
} }