From abec4cbf1f199edadadda483373740b2abd35265 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 29 Oct 2003 17:36:57 +0000
Subject: [PATCH] compact_fsm_storage() does need to handle the case where a
relation's FSM data has to be both moved down and compressed. Per report
from Dror Matalon.
---
src/backend/storage/freespace/freespace.c | 28 +++++++++++++++--------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/src/backend/storage/freespace/freespace.c b/src/backend/storage/freespace/freespace.c
index 51f8e4ea5da..b5e1a53b35e 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 1.23 2003/09/29 00:05:25 petere Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.24 2003/10/29 17:36:57 tgl Exp $
*
*
* NOTES:
@@ -1432,19 +1432,29 @@ compact_fsm_storage(void)
/*
* It's possible that we have to move data down, not up, if the
- * allocations of previous rels expanded. This should mean that
+ * allocations of previous rels expanded. This normally means that
* our allocation expanded too (or at least got no worse), and
- * ditto for later rels. So there should be room --- but we might
- * have to push down following rels to make it. We don't want to
- * do the push more than once, so pack everything against the end
- * of the arena if so.
+ * ditto for later rels. So there should be room to move all our
+ * data down without dropping any --- but we might have to push down
+ * following rels to acquire the room. We don't want to do the push
+ * more than once, so pack everything against the end of the arena
+ * if so.
+ *
+ * In corner cases where roundoff has affected our allocation, it's
+ * possible that we have to move down and compress our data too.
+ * Since this case is extremely infrequent, we do not try to be smart
+ * about it --- we just drop pages from the end of the rel's data.
*/
if (newChunkIndex > oldChunkIndex)
{
int limitChunkIndex;
if (newAllocPages < fsmrel->storedPages)
- elog(PANIC, "can't juggle and compress too");
+ {
+ /* move and compress --- just drop excess pages */
+ fsmrel->storedPages = newAllocPages;
+ curChunks = fsm_current_chunks(fsmrel);
+ }
if (fsmrel->nextPhysical != NULL)
limitChunkIndex = fsmrel->nextPhysical->firstChunk;
else
@@ -1459,7 +1469,7 @@ compact_fsm_storage(void)
else
limitChunkIndex = FreeSpaceMap->totalChunks;
if (newChunkIndex + curChunks > limitChunkIndex)
- elog(PANIC, "insufficient room");
+ elog(PANIC, "insufficient room in FSM");
}
memmove(newLocation, oldLocation, curChunks * CHUNKBYTES);
}
@@ -1535,7 +1545,7 @@ push_fsm_rels_after(FSMRelation *afterRel)
if (newChunkIndex < oldChunkIndex)
{
/* trouble... */
- elog(PANIC, "out of room");
+ elog(PANIC, "insufficient room in FSM");
}
else if (newChunkIndex > oldChunkIndex)
{
--
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