Issue with extension updates to pg_extension table

For reasons I've brought up before
(http://archives.postgresql.org/pgsql-general/2012-06/msg00174.php) I
need to stop some of my extension tables from dumping data when a
schema only dump is done because they have the potential to contain A
LOT of data.

For reference my extension is https://github.com/omniti-labs/pg_jobmon

The problem I'm having is changing this with an extension update. I
want to turn off the data dumping for the job_log and job_detail
tables. The only method I've found to do this is by directly updating
the extconfig column in the pg_extensions table. If I run this update
directly via psql, it works fine.

db=# select unnest(extconfig) as oid,
split_part(unnest(extconfig)::regclass::text, '.', 2) as tablename
from pg_extension where extname = 'pg_jobmon';
oid | tablename
-----------+------------------
214224990 | job_log
214225005 | job_detail
214225022 | job_check_log
214225028 | job_check_config
214225038 | job_status_text
214972369 | dblink_mapping
(6 rows)

db=# begin;
BEGIN
db=# UPDATE pg_extension SET extconfig = (SELECT array_agg(t.oid) FROM (
db(# SELECT unnest(extconfig) AS oid,
split_part(unnest(extconfig)::regclass::text, '.', 2) AS tablename
db(# FROM pg_extension WHERE extname = 'pg_jobmon') t
db(# WHERE t.tablename NOT IN ('job_log', 'job_detail') ) WHERE
extname = 'pg_jobmon';
UPDATE 1
db=# select unnest(extconfig) as oid,
split_part(unnest(extconfig)::regclass::text, '.', 2) as tablename
from pg_extension where extname = 'pg_jobmon';
oid | tablename
-----------+------------------
214225022 | job_check_log
214225028 | job_check_config
214225038 | job_status_text
214972369 | dblink_mapping
(4 rows)

db=# rollback;
ROLLBACK

However, if I run this exact same query as an extension update, it does nothing

db=# select unnest(extconfig) as oid,
split_part(unnest(extconfig)::regclass::text, '.', 2) as tablename
from pg_extension where extname = 'pg_jobmon';
oid | tablename
-----------+------------------
214224990 | job_log
214225005 | job_detail
214225022 | job_check_log
214225028 | job_check_config
214225038 | job_status_text
214972369 | dblink_mapping
(6 rows)

db=# alter extension pg_jobmon update to '0.3.3';
ALTER EXTENSION
db=# select unnest(extconfig) as oid,
split_part(unnest(extconfig)::regclass::text, '.', 2) as tablename
from pg_extension where extname = 'pg_jobmon';
oid | tablename
-----------+------------------
214224990 | job_log
214225005 | job_detail
214225022 | job_check_log
214225028 | job_check_config
214225038 | job_status_text
214972369 | dblink_mapping
(6 rows)

I know this isn't really something that would be done often, but it
just seemed a rather odd behavior so I thought I'd bring it up in case
it's something that can be easily fixed.

--
Keith Fiske
Database Administrator
OmniTI Computer Consulting, Inc.
443.325.1357 x251