From 48188e1621bb6711e7d092bee48523b18cd80177 Mon Sep 17 00:00:00 2001
From: Tom Lane
Date: Sun, 5 Nov 2006 22:42:10 +0000
Subject: Fix recently-understood problems with handling of XID freezing,
 particularly in PITR scenarios.  We now WAL-log the replacement of old XIDs
 with FrozenTransactionId, so that such replacement is guaranteed to propagate
 to PITR slave databases.  Also, rather than relying on hint-bit updates to be
 preserved, pg_clog is not truncated until all instances of an XID are known
 to have been replaced by FrozenTransactionId.  Add new GUC variables and
 pg_autovacuum columns to allow management of the freezing policy, so that
 users can trade off the size of pg_clog against the amount of freezing work
 done.  Revise the already-existing code that forces autovacuum of tables
 approaching the wraparound point to make it more bulletproof; also, revise
 the autovacuum logic so that anti-wraparound vacuuming is done per-table
 rather than per-database.  initdb forced because of changes in pg_class,
 pg_database, and pg_autovacuum catalogs.  Heikki Linnakangas, Simon Riggs,
 and Tom Lane.

---
 src/include/access/clog.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'src/include/access/clog.h')

diff --git a/src/include/access/clog.h b/src/include/access/clog.h
index 999f15bdf7f..0cb76000a29 100644
--- a/src/include/access/clog.h
+++ b/src/include/access/clog.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/clog.h,v 1.17 2006/03/24 04:32:13 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/clog.h,v 1.18 2006/11/05 22:42:09 tgl Exp $
  */
 #ifndef CLOG_H
 #define CLOG_H
@@ -46,6 +46,7 @@ extern void TruncateCLOG(TransactionId oldestXact);
 
 /* XLOG stuff */
 #define CLOG_ZEROPAGE		0x00
+#define CLOG_TRUNCATE		0x10
 
 extern void clog_redo(XLogRecPtr lsn, XLogRecord *record);
 extern void clog_desc(StringInfo buf, uint8 xl_info, char *rec);
-- 
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