Introduce wal_level GUC to explicitly control if information needed for

archival or hot standby should be WAL-logged, instead of deducing that from
other options like archive_mode. This replaces recovery_connections GUC in
the primary, where it now has no effect, but it's still used in the standby
to enable/disable hot standby.

Remove the WAL-logging of "unlogged operations", like creating an index
without WAL-logging and fsyncing it at the end. Instead, we keep a copy of
the wal_mode setting and the settings that affect how much shared memory a
hot standby server needs to track master transactions (max_connections,
max_prepared_xacts, max_locks_per_xact) in pg_control. Whenever the settings
change, at server restart, write a WAL record noting the new settings and
update pg_control. This allows us to notice the change in those settings in
the standby at the right moment, they used to be included in checkpoint
records, but that meant that a changed value was not reflected in the
standby until the first checkpoint after the change.

Bump PG_CONTROL_VERSION and XLOG_PAGE_MAGIC. Whack XLOG_PAGE_MAGIC back to
the sequence it used to follow, before hot standby and subsequent patches
changed it to 0x9003.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/bin/pg_resetxlog/pg_resetxlog.c b/src/bin/pg_resetxlog/pg_resetxlog.c
index d14df9cec8..a8a43c44f0 100644
--- a/src/bin/pg_resetxlog/pg_resetxlog.c
+++ b/src/bin/pg_resetxlog/pg_resetxlog.c
@@ -23,7 +23,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.78 2010/02/26 02:01:17 momjian Exp $
+ * $PostgreSQL: pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.79 2010/04/28 16:10:43 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -628,6 +628,15 @@ RewriteControlFile(void)
 	ControlFile.backupStartPoint.xlogid = 0;
 	ControlFile.backupStartPoint.xrecoff = 0;
 
+	/*
+	 * Use the defaults for max_* settings. The values don't matter
+	 * as long as wal_level='minimal'.
+	 */
+	ControlFile.MaxConnections = 100;
+	ControlFile.max_prepared_xacts = 0;
+	ControlFile.max_locks_per_xact = 64;
+	ControlFile.wal_level = WAL_LEVEL_MINIMAL;
+
 	/* Now we can force the recorded xlog seg size to the right thing. */
 	ControlFile.xlog_seg_size = XLogSegSize;