From: | Paul Jungwirth <pj(at)illuminatedcomputing(dot)com> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: Check constraints. |
Date: | 2018-03-27 14:44:56 |
Message-ID: | cf4e649e-a025-f1a4-25e9-58d4747ebec9@illuminatedcomputing.com |
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Thread: | |
Lists: | pgsql-general |
On 03/27/2018 04:23 AM, Steve Rogerson wrote:
> I am trying to add/change a constraint programmatically, but not if it
> already exists, and is the same as before.
> ...
> Is there a way of getting the "normalised" version of constraint so decide if
> I need to update the constraint if one already exists?
Hi Steve,
I wrote a Ruby gem to do this some years ago. Here is the SQL I used:
SELECT c.conname,
t.relname,
pg_get_expr(c.conbin, c.conrelid)
FROM pg_catalog.pg_constraint c,
pg_catalog.pg_class t,
pg_catalog.pg_namespace n
WHERE c.contype = 'c'
AND c.conrelid = t.oid
AND t.relkind = 'r'
AND n.oid = t.relnamespace
AND n.nspname NOT IN ('pg_catalog', 'pg_toast')
AND pg_catalog.pg_table_is_visible(t.oid)
I haven't used it against the last few Postgres versions, but it
probably still works or needs only minor adjustments.
--
Paul ~{:-)
pj(at)illuminatedcomputing(dot)com
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