From: Simon Riggs <simon@2ndQuadrant.com>
Date: Fri, 25 Sep 2009 12:51:00 +0000 (+0100)
Subject: Updated log message and docs caveat about delayed start of hot standby queries.
X-Git-Url: http://waps.l3s.uni-hannover.de/gitweb/?a=commitdiff_plain;h=e4aa8b17e2d4441d43e5757581743562675bcdf6;p=users%2Fsimon%2Fpostgres.git

Updated log message and docs caveat about delayed start of hot standby queries.
---

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index 5a4d030813..b32b74b126 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -2348,7 +2348,7 @@ LOG:  database system is ready to accept read only connections
 	themselves.  Users will be able to write large sort temp files and
 	re-generate relcache info files, so there is no part of the database
 	that is truly read-only during hot standby mode. There is no restriction
-	on use of set returning functions, or other users of tuplestore/tuplesort
+	on the use of set returning functions, or other users of tuplestore/tuplesort
 	code. Note also that writes to remote databases will still be possible,
 	even though the transaction is read-only locally.
    </para>
@@ -2564,6 +2564,15 @@ LOG:  database system is ready to accept read only connections
 	 available for use when running queries during recovery.
     </para>
    </listitem>
+   <listitem>
+    <para>
+     Full knowledge of running transactions is required before snapshots
+	 may be taken. Transactions that take use large numbers of subtransactions
+	 (currently greater than 64) will delay the start of read only
+	 connections until the completion of the longest running write transaction.
+	 If this situation occurs explanatory messages will be sent to server log.
+    </para>
+   </listitem>
   </itemizedlist>
 
    </para>
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 211588a8a5..61d63d37d8 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -502,8 +502,8 @@ ProcArrayApplyRecoveryInfo(XLogRecPtr lsn, xl_xact_running_xacts *xlrec)
 	if (!xlrec->subxid_overflow)
 		recoverySnapshotValid = true;
 	else
-		elog(trace_recovery(DEBUG2), 
-				"running xact data has incomplete subtransaction data");
+		ereport(LOG, 
+				(errmsg("consistent state delayed because recovery snapshot incomplete")));
 
 	xids = palloc(sizeof(TransactionId) * (xlrec->xcnt + xlrec->subxcnt));
 	nxids = 0;