How do I resolve Postgresql error, 'no collation was derived for column "foo" with collatable type citext'?

Question

Just recently I upgraded from Postgresql 8.4.11 to 9.1.3. I used pg_dump in the process. Now I'm getting an error:

ERROR: no collation was derived for column "vin" with collatable type citext
HINT: Use the COLLATE clause to set the collation explicitly.

This is a continuation of the problem that I had earlier. It seems the fix suggested in the Release Notes did not catch custom domains. It seems as if the CREATE DOMAIN statement in 8.4 didn't even support the COLLATE clause.

This is how I created the vin type,

CREATE DOMAIN inventory.valid_vin AS citext
  CHECK ( inventory.valid_vin( VALUE ) );

Answer 1

For more information on this find our correspondence on this thread:

• Thread: http://archives.postgresql.org/pgsql-general/2012-05/msg00262.php

Problem

The problem comes right from the horses mouth, Tom Lane,

Well, if that's how you're creating citext *, then yeah it's broken. As of 9.1 the citext type needs to be created with the attribute "COLLATABLE = true". The suggested UPDATE statements are a means of correcting a failure to do that after-the-fact, but they don't cover any domains that have already been created on top of citext.

Source: http://archives.postgresql.org/pgsql-general/2012-05/msg00262.php

* I was creating citext however my specific dump had it created, there was nothing special.

So a dump/restore from 8.3 -> 9.1 is not supported if you've got a domain over citext.

Solution

You can get around this problem by first doing:

• CREATE EXTENSION citext before you load the dump.
• or, by hacking the patch to operate on DOMAINS over citext.