postgresql_default.conf: Make sure the "disk_io" query does not return NULLs.

Starting with some version between 8.3.3 and 8.3.6, pg_statio_*_tables returns
NULL instead of 0 for statistics if no instance of the appropriate relation
exists. PQgetvalue() returns an empty string in that case which would then
result in error messages when udb_result_submit() tries to convert that to a
number.

Now, the "disk_io" query uses PostgreSQL's coalesce() function to make sure 0
is returned instead of NULL.

diff --git a/src/postgresql_default.conf b/src/postgresql_default.conf
index 61844a0..5b024ca 100644 (file)
--- a/src/postgresql_default.conf
+++ b/src/postgresql_default.conf
@@ -67,10 +67,14 @@
 </Query>
 
 <Query disk_io>
-       Query "SELECT sum(heap_blks_read), sum(heap_blks_hit), \
-                       sum(idx_blks_read), sum(idx_blks_hit), \
-                       sum(toast_blks_read), sum(toast_blks_hit), \
-                       sum(tidx_blks_read), sum(tidx_blks_hit) \
+       Query "SELECT coalesce(sum(heap_blks_read), 0), \
+                       coalesce(sum(heap_blks_hit), 0), \
+                       coalesce(sum(idx_blks_read), 0), \
+                       coalesce(sum(idx_blks_hit), 0), \
+                       coalesce(sum(toast_blks_read), 0), \
+                       coalesce(sum(toast_blks_hit), 0), \
+                       coalesce(sum(tidx_blks_read), 0), \
+                       coalesce(sum(tidx_blks_hit), 0) \
                FROM pg_statio_user_tables;"
 
        Column pg_blks heap_read
@@ -91,3 +95,5 @@
        Column pg_db_size
 </Query>
 
+# vim: set ft=config :
+