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authorTom Lane <tgl@sss.pgh.pa.us>2009-08-31 02:23:23 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2009-08-31 02:23:23 +0000
commit25ec228ef760eb91c094cc3b6dea7257cc22ffb5 (patch)
tree59d9d82fa2a61c1c27174d9b2f462536a7db39ee /src/backend/utils/misc/guc.c
parente1cc64197bd3a8d6fd5e4ca6830d514130f2737f (diff)
downloadpostgresql-25ec228ef760eb91c094cc3b6dea7257cc22ffb5.tar.gz
postgresql-25ec228ef760eb91c094cc3b6dea7257cc22ffb5.zip
Track the current XID wrap limit (or more accurately, the oldest unfrozen
XID) in checkpoint records. This eliminates the need to recompute the value from scratch during database startup, which is one of the two remaining reasons for the flatfile code to exist. It should also simplify life for hot-standby operation. To avoid bloating the checkpoint records unreasonably, I switched from tracking the oldest database by name to tracking it by OID. This turns out to save cycles in general (everywhere but the warning-generating paths, which we hardly care about) and also helps us deal with the case that the oldest database got dropped instead of being vacuumed. The prior coding might go for a long time without updating the wrap limit in that case, which is bad because it might result in a lot of useless autovacuum activity.
Diffstat (limited to 'src/backend/utils/misc/guc.c')
-rw-r--r--src/backend/utils/misc/guc.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 6bc0c197b0f..66904e6b091 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.512 2009/08/29 19:26:51 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.513 2009/08/31 02:23:22 tgl Exp $
*
*--------------------------------------------------------------------
*/
@@ -1864,6 +1864,7 @@ static struct config_int ConfigureNamesInt[] =
NULL
},
&autovacuum_freeze_max_age,
+ /* see pg_resetxlog if you change the upper-limit value */
200000000, 100000000, 2000000000, NULL, NULL
},
{