From be926474be57ae73ae2052b968fd785a0096514e Mon Sep 17 00:00:00 2001
From: Magnus Hagander <magnus@hagander.net>
Date: Fri, 25 Jan 2013 09:44:14 +0100
Subject: [PATCH] Make pg_dump exclude unlogged table data on hot standby
slaves
Noted by Joe Van Dyk
---
doc/src/sgml/ref/pg_dump.sgml | 3 ++-
src/bin/pg_dump/pg_dump.c | 18 ++++++++++++++++++
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index d936cf185df..152edcbe6ed 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -713,7 +713,8 @@ PostgreSQL documentation
<para>
Do not dump the contents of unlogged tables. This option has no
effect on whether or not the table definitions (schema) are dumped;
- it only suppresses dumping the table data.
+ it only suppresses dumping the table data. Data in unlogged tables
+ is always excluded when dumping from a standby server.
</para>
</listitem>
</varlistentry>
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 6295b5bf2cc..9f1ef32b158 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -605,6 +605,24 @@ main(int argc, char **argv)
if (fout->remoteVersion < 90100)
no_security_labels = 1;
+ /*
+ * When running against 9.0 or later, check if we are in recovery mode,
+ * which means we are on a hot standby.
+ */
+ if (fout->remoteVersion >= 90000)
+ {
+ PGresult *res = ExecuteSqlQueryForSingleRow(fout, "SELECT pg_catalog.pg_is_in_recovery()");
+ if (strcmp(PQgetvalue(res, 0, 0), "t") == 0)
+ {
+ /*
+ * On hot standby slaves, never try to dump unlogged table data,
+ * since it will just throw an error.
+ */
+ no_unlogged_table_data = true;
+ }
+ PQclear(res);
+ }
+
/*
* Start transaction-snapshot mode transaction to dump consistent data.
*/
--
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