Re: regarding debugging?

Checking how your PgSQL statements are executed, can be done using
EXPLAIN [1].

EXPLAIN ANALYZE will also execute (but not dry-run!) your statement.

I work with a seperate development and production database. Once the
changes to the schema in the development DB are done, I commit them to
the production DB using ActiveRecord migrations. You could do the same
with an advanced schema diff tool such as pgdiff [2] or zongle [3].
 - Rowan

[1] http://www.postgresql.org/docs/current/interactive/sql-explain.html
[2] http://pgdiff.sourceforge.net/
[3] http://zongle.sourceforge.net/