Introduce Streaming Replication.

This includes two new kinds of postmaster processes, walsenders and
walreceiver. Walreceiver is responsible for connecting to the primary server
and streaming WAL to disk, while walsender runs in the primary server and
streams WAL from disk to the client.

Documentation still needs work, but the basics are there. We will probably
pull the replication section to a new chapter later on, as well as the
sections describing file-based replication. But let's do that as a separate
patch, so that it's easier to see what has been added/changed. This patch
also adds a new section to the chapter about FE/BE protocol, documenting the
protocol used by walsender/walreceivxer.

Bump catalog version because of two new functions,
pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), for
monitoring the progress of replication.

Fujii Masao, with additional hacking by me

2 files changed, 9 insertions, 5 deletions

diff --git a/src/include/storage/pmsignal.h b/src/include/storage/pmsignal.h
index 4db0f8c1db9..75ef17a5a0a 100644
--- a/src/include/storage/pmsignal.h
+++ b/src/include/storage/pmsignal.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/pmsignal.h,v 1.27 2010/01/02 16:58:08 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/pmsignal.h,v 1.28 2010/01/15 09:19:09 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,6 +29,8 @@ typedef enum
 	PMSIGNAL_ROTATE_LOGFILE,	/* send SIGUSR1 to syslogger to rotate logfile */
 	PMSIGNAL_START_AUTOVAC_LAUNCHER,	/* start an autovacuum launcher */
 	PMSIGNAL_START_AUTOVAC_WORKER,		/* start an autovacuum worker */
+	PMSIGNAL_START_WALRECEIVER,			/* start a walreceiver */
+	PMSIGNAL_SHUTDOWN_WALRECEIVER,		/* shut down a walreceiver */
 
 	NUM_PMSIGNALS				/* Must be last value of enum! */
 } PMSignalReason;
@@ -45,7 +47,9 @@ extern void SendPostmasterSignal(PMSignalReason reason);
 extern bool CheckPostmasterSignal(PMSignalReason reason);
 extern int	AssignPostmasterChildSlot(void);
 extern bool ReleasePostmasterChildSlot(int slot);
+extern bool IsPostmasterChildWalSender(int slot);
 extern void MarkPostmasterChildActive(void);
+extern void MarkPostmasterChildWalSender(void);
 extern void MarkPostmasterChildInactive(void);
 extern bool PostmasterIsAlive(bool amDirectChild);
 
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index ba725d8fa81..cee02c359d7 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.116 2010/01/02 16:58:08 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.117 2010/01/15 09:19:09 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -152,10 +152,10 @@ typedef struct PROC_HDR
  * ie things that aren't full-fledged backends but need shmem access.
  *
  * Background writer and WAL writer run during normal operation. Startup
- * process also consumes one slot, but WAL writer is launched only after
- * startup has exited, so we only need 2 slots.
+ * process and WAL receiver also consume 2 slots, but WAL writer is
+ * launched only after startup has exited, so we only need 3 slots.
  */
-#define NUM_AUXILIARY_PROCS		2
+#define NUM_AUXILIARY_PROCS		3
 
 
 /* configurable options */