Make pg_dump exclude unlogged table data on hot standby slaves

Noted by Joe Van Dyk

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 0d26f15c98f2d455d46c89e4bdfb2d0c3ebdd308..a275eae5c6ab7d024936337bb229608ea9eaeecf 100644 (file)
--- 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 f432579449fe289114745970cedf575f66e1ae08..1fe9d75b15a9858a5310f7181c31a691568de46f 100644 (file)
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -603,6 +603,24 @@ 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.
         */