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 to have been replaced by FrozenTransactionId.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/transam.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

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

diff --git a/src/include/access/transam.h b/src/include/access/transam.h
index f1b91145f67..96cc65f94d5 100644
--- a/src/include/access/transam.h
+++ b/src/include/access/transam.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/transam.h,v 1.58 2006/07/10 16:20:51 alvherre Exp $
+ * $PostgreSQL: pgsql/src/include/access/transam.h,v 1.59 2006/11/05 22:42:10 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -23,7 +23,7 @@
  * always be considered valid.
  *
  * FirstNormalTransactionId is the first "normal" transaction id.
- * Note: if you need to change it, you must change it in pg_class.h as well.
+ * Note: if you need to change it, you must change pg_class.h as well.
  * ----------------
  */
 #define InvalidTransactionId		((TransactionId) 0)
@@ -88,6 +88,9 @@ typedef struct VariableCacheData
 	Oid			nextOid;		/* next OID to assign */
 	uint32		oidCount;		/* OIDs available before must do XLOG work */
 	TransactionId nextXid;		/* next XID to assign */
+
+	TransactionId oldestXid;	/* cluster-wide minimum datfrozenxid */
+	TransactionId xidVacLimit;	/* start forcing autovacuums here */
 	TransactionId xidWarnLimit; /* start complaining here */
 	TransactionId xidStopLimit; /* refuse to advance nextXid beyond here */
 	TransactionId xidWrapLimit; /* where the world ends */
@@ -124,7 +127,7 @@ extern bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2);
 /* in transam/varsup.c */
 extern TransactionId GetNewTransactionId(bool isSubXact);
 extern TransactionId ReadNewTransactionId(void);
-extern void SetTransactionIdLimit(TransactionId oldest_datminxid,
+extern void SetTransactionIdLimit(TransactionId oldest_datfrozenxid,
 					  Name oldest_datname);
 extern Oid	GetNewObjectId(void);
 
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