From: | "Nick Fankhauser" <nickf(at)ontko(dot)com> |
---|---|
To: | "pgsql-admin" <pgsql-admin(at)postgresql(dot)org> |
Cc: | "Ray Ontko" <rayo(at)ontko(dot)com> |
Subject: | Is it safe to increase pg_attribute.atttypmod ? |
Date: | 2002-05-20 20:56:42 |
Message-ID: | NEBBLAAHGLEEPCGOBHDGEEPDEPAA.nickf@ontko.com |
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Thread: | |
Lists: | pgsql-admin |
Hi-
We need to increase the length of a varchar field, and couldn't find a way
to do it using "alter table". Since the alternative is copying & re-creating
a very large table, we starting poking around under the hood & found that
pg_attribute.atttypmod seems to be always equal to the length plus 4 in the
case of varchar fields.
We created a test table and altered the varchar length on a field by
increasing pg_attribute.atttypmod, and the length seemed to change and act
as expected.
The update to change a varchar(10) field to varchar(40) looked like this:
update pg_attribute set atttypmod = 44
where attrelid = ( select oid from pg_class where relname = 'test' )
and attname = 'oldtest' ;
Is this a smart thing to do?
Are there other hidden related bits of data that will come back to haunt us
later?
-Nick
--------------------------------------------------------------------------
Nick Fankhauser nickf(at)ontko(dot)com Phone 1.765.935.4283 Fax 1.765.962.9788
Ray Ontko & Co. Software Consulting Services http://www.ontko.com/
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