Date: Thu, 7 Apr 2005 13:24:53 -0700
From: Craig Addleman <craiga-@-sharechive.com>
To: pgsql-sql@postgresql.org
Subject: Re: DROP TYPE without error?
Message-ID: <20050407202453.GA3821@craiga-linux.sharechive.com>
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	pgsql-sql@postgresql.org
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I was confronted with a similar problem. I have several scripts which create
or modify schemas, and each run in a single transaction. So, dropping a 
non-existent TYPE will produce a show-stopping error. I wrote this function,
and others for various database objects:

CREATE OR REPLACE FUNCTION dba_droptype(varchar) RETURNS boolean AS '
DECLARE
   p_type ALIAS FOR $1;
   v_exists boolean;
BEGIN
   SELECT INTO v_exists TRUE WHERE EXISTS(
      SELECT 1 FROM pg_type
      WHERE typname = p_type::name);
   IF v_exists THEN
      RAISE NOTICE ''Dropping TYPE %'', p_type;
      EXECUTE ''DROP TYPE '' || p_type || '' CASCADE'';
   END IF;
   RETURN FOUND;
END;
' LANGUAGE 'plpgsql';

COMMENT ON FUNCTION dba_droptype(varchar) IS '
Usage: SELECT dba_drop_type(type_name)
Checks for existence of a type and drops it if found.
Implements DROP TYPE CASCADE; if a function or other object
depends on the type, that object will also be dropped. 
Returns TRUE if successful, returns FALSE if type is
not found.';

-- 
Craig Addleman
DBA
ShareChive LLC

* Philippe Lang <philippe.lang@attiksystem.ch> [2005-04-06 05:59]:
> Hi,
> 
> Since it is not possible to use CREATE OR REPLACE TYPE, is there a way
> of using DROP TYPE on a non-existing type, without causing the entire
> script to abort? It may sound crazy to ask for this, but it could be
> really useful in my case, where Pl/Pgsql and Pl/Perl code is being
> generated automatically, based on data found in a database.
> 
> Thanks
> 
> -----------------
> Philippe Lang
> 
> 
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