Reimplement free-space-map management as per recent discussions.

Adjustable threshold is gone in favor of keeping track of total requested
page storage and doling out proportional fractions to each relation
(with a minimum amount per relation, and some quantization of the results
to avoid thrashing with small changes in page counts).  Provide special-
case code for indexes so as not to waste space storing useless page
free space counts.  Restructure internal data storage to be a flat array
instead of list-of-chunks; this may cost a little more work in data
copying when reorganizing, but allows binary search to be used during
lookup_fsm_page_entry().

2 files changed, 11 insertions, 27 deletions

diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index c8fb7628ead..f9d108e769b 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.63 2003/02/23 23:20:52 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.64 2003/03/04 21:51:20 tgl Exp $
  *
  *	NOTES
  *	   Postgres btree pages look like ordinary relation pages.	The opaque
@@ -401,15 +401,10 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
 		 * that the page is still free.  (For example, an already-free page
 		 * could have been re-used between the time the last VACUUM scanned
 		 * it and the time the VACUUM made its FSM updates.)
-		 *
-		 * The request size should be more than half of what btvacuumcleanup
-		 * logs as the per-page free space.  We use BLCKSZ/2 and BLCKSZ-1
-		 * to try to get some use out of FSM's space management algorithm.
-		 * XXX this needs some more thought...
 		 */
 		for (;;)
 		{
-			blkno = GetPageWithFreeSpace(&rel->rd_node, BLCKSZ/2);
+			blkno = GetFreeIndexPage(&rel->rd_node);
 			if (blkno == InvalidBlockNumber)
 				break;
 			buf = ReadBuffer(rel, blkno);
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index c393e907b59..b1722244e6d 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.100 2003/02/24 00:57:17 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.101 2003/03/04 21:51:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -697,7 +697,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
 	IndexBulkDeleteResult *stats = (IndexBulkDeleteResult *) PG_GETARG_POINTER(2);
 	BlockNumber num_pages;
 	BlockNumber blkno;
-	PageFreeSpaceInfo *pageSpaces;
+	BlockNumber *freePages;
 	int			nFreePages,
 				maxFreePages;
 	BlockNumber pages_deleted = 0;
@@ -712,7 +712,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
 	maxFreePages = MaxFSMPages;
 	if ((BlockNumber) maxFreePages > num_pages)
 		maxFreePages = (int) num_pages + 1;	/* +1 to avoid palloc(0) */
-	pageSpaces = (PageFreeSpaceInfo *) palloc(maxFreePages * sizeof(PageFreeSpaceInfo));
+	freePages = (BlockNumber *) palloc(maxFreePages * sizeof(BlockNumber));
 	nFreePages = 0;
 
 	/* Create a temporary memory context to run _bt_pagedel in */
@@ -740,12 +740,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
 		{
 			/* Okay to recycle this page */
 			if (nFreePages < maxFreePages)
-			{
-				pageSpaces[nFreePages].blkno = blkno;
-				/* claimed avail-space must be < BLCKSZ */
-				pageSpaces[nFreePages].avail = BLCKSZ-1;
-				nFreePages++;
-			}
+				freePages[nFreePages++] = blkno;
 			pages_deleted++;
 		}
 		else if (P_ISDELETED(opaque))
@@ -781,12 +776,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
 			if (ndel && info->vacuum_full)
 			{
 				if (nFreePages < maxFreePages)
-				{
-					pageSpaces[nFreePages].blkno = blkno;
-					/* claimed avail-space must be < BLCKSZ */
-					pageSpaces[nFreePages].avail = BLCKSZ-1;
-					nFreePages++;
-				}
+					freePages[nFreePages++] = blkno;
 			}
 
 			MemoryContextSwitchTo(oldcontext);
@@ -805,8 +795,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
 	{
 		BlockNumber	new_pages = num_pages;
 
-		while (nFreePages > 0 &&
-			   pageSpaces[nFreePages-1].blkno == new_pages-1)
+		while (nFreePages > 0 && freePages[nFreePages-1] == new_pages-1)
 		{
 			new_pages--;
 			pages_deleted--;
@@ -841,12 +830,12 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
 
 	/*
 	 * Update the shared Free Space Map with the info we now have about
-	 * free space in the index, discarding any old info the map may have.
+	 * free pages in the index, discarding any old info the map may have.
 	 * We do not need to sort the page numbers; they're in order already.
 	 */
-	MultiRecordFreeSpace(&rel->rd_node, 0, nFreePages, pageSpaces);
+	RecordIndexFreeSpace(&rel->rd_node, nFreePages, freePages);
 
-	pfree(pageSpaces);
+	pfree(freePages);
 
 	MemoryContextDelete(mycontext);