From 3110cd237cb89b30f87d8ad1c83f06b9440b3023 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Tue, 15 Feb 2005 03:50:07 +0000
Subject: [PATCH] Update comment on VACUUM FULL.
Manfred Koizar
---
src/backend/commands/vacuum.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index cdfc02328d2..d0ccf310cc4 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.299 2004/12/31 21:59:42 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.300 2005/02/15 03:50:07 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1703,20 +1703,25 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
tuple_len = tuple.t_len = ItemIdGetLength(itemid);
ItemPointerSet(&(tuple.t_self), blkno, offnum);
- /*
+ /* ---
* VACUUM FULL has an exclusive lock on the relation. So
* normally no other transaction can have pending INSERTs or
- * DELETEs in this relation. A tuple is either (a) a tuple in
- * a system catalog, inserted or deleted by a not yet
- * committed transaction or (b) dead (XMIN_INVALID or
- * XMAX_COMMITTED) or (c) inserted by a committed xact
- * (XMIN_COMMITTED) or (d) moved by the currently running
- * VACUUM. In case (a) we wouldn't be in repair_frag() at all.
+ * DELETEs in this relation. A tuple is either:
+ * (a) a tuple in a system catalog, inserted or deleted
+ * by a not yet committed transaction
+ * (b) known dead (XMIN_INVALID, or XMAX_COMMITTED and xmax
+ * is visible to all active transactions)
+ * (c) inserted by a committed xact (XMIN_COMMITTED)
+ * (d) moved by the currently running VACUUM.
+ * (e) deleted (XMAX_COMMITTED) but at least one active
+ * transaction does not see the deleting transaction
+ * In case (a) we wouldn't be in repair_frag() at all.
* In case (b) we cannot be here, because scan_heap() has
* already marked the item as unused, see continue above. Case
* (c) is what normally is to be expected. Case (d) is only
* possible, if a whole tuple chain has been moved while
* processing this or a higher numbered block.
+ * ---
*/
if (!(tuple.t_data->t_infomask & HEAP_XMIN_COMMITTED))
{
--
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