Minor performance improvement in MultiRecordFreeSpace.

tglsfdc · tglsfdc · commit 8a59f336bbb8 · 2001-07-19T21:25:37.000Z
diff --git 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);
 }

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`* Portions Copyright (c) 1994, Regents of the University of California`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.3 2001/07/02 20:50:46 tgl Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.4 2001/07/19 21:25:37 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*`
`14`	`14`	`* NOTES:`
`@@ -419,9 +419,23 @@ MultiRecordFreeSpace(RelFileNode *rel,`
`419`	`419`	`*`
`420`	`420`	`* XXX we could probably be smarter about this than doing it`
`421`	`421`	`* completely separately for each one. FIXME later.`
	`422`	`+ *`
	`423`	`+ * One thing we can do is short-circuit the process entirely if`
	`424`	`+ * a page (a) has too little free space to be recorded, and (b)`
	`425`	`+ * is within the minPage..maxPage range --- then we deleted any`
	`426`	`+ * old entry above, and we aren't going to make a new one.`
	`427`	`+ * This is particularly useful since in most cases, all the passed`
	`428`	`+ * pages will in fact be in the minPage..maxPage range.`
`422`	`429`	`*/`
`423`	`430`	`for (i = 0; i < nPages; i++)`
`424`		`- fsm_record_free_space(fsmrel, pages[i], spaceAvail[i]);`
	`431`	`+ {`
	`432`	`+ BlockNumber page = pages[i];`
	`433`	`+ Size avail = spaceAvail[i];`
	`434`	`+`
	`435`	`+ if (avail >= fsmrel->threshold \|\|`
	`436`	`+ page < minPage \|\| page > maxPage)`
	`437`	`+ fsm_record_free_space(fsmrel, page, avail);`
	`438`	`+ }`
`425`	`439`	`}`
`426`	`440`	`SpinRelease(FreeSpaceLock);`
`427`	`441`	`}`