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 ) );
  • Ouch! My first instinct would be to alter any such columns to the base citext type, drop the domain, create it again, and alter the columns back; but that's a totally untested suggestion which might not be on target.
    – kgrittn
    Commented May 8, 2012 at 22:15
  • I posted to the postgresql-general list. Commented May 10, 2012 at 17:30
  • Thanks for cross-linking your SO post and list post. Much appreciated. Commented Oct 19, 2012 at 0:08

1 Answer 1


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


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.


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.

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