From 8a59f336bbb8d6829e88c89896472b497d809606 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 19 Jul 2001 21:25:37 +0000
Subject: [PATCH] Minor performance improvement in MultiRecordFreeSpace.
---
src/backend/storage/freespace/freespace.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/src/backend/storage/freespace/freespace.c b/src/backend/storage/freespace/freespace.c
index a7866745f82..fec9f594a61 100644
--- a/src/backend/storage/freespace/freespace.c
+++ b/src/backend/storage/freespace/freespace.c
@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* 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:
@@ -419,9 +419,23 @@ MultiRecordFreeSpace(RelFileNode *rel,
*
* XXX we could probably be smarter about this than doing it
* 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++)
- 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);
}
--
GitLab