AI Rumman <rummandba@gmail.com> writes:
> I started the following query in Postgresql 9.1 where only this sql is
> running on the host and it has been taking more than an hour and still
> running.
> alter table userdata.table1 alter column name type varchar(512);
Pre-9.2 releases don't realize that that doesn't require a table rewrite.
You can either wait it out, or if you're feeling brave, manually modify
the column's pg_attribute.atttypmod field.
regards, tom lane