Re: alter table without an ACCESS EXCLUSIVE lock

Andreas Berger <4postgres@gmail.com> writes:
> i'm searching for a solution for changing the type of a column, e.g. from
> varchar(128) to varchar(512), without an ACCESS EXCLUSIVE lock.

That specific case (increasing the max length of a varchar column) could
be handled by hacking the pg_attribute.atttypmod entry for the column,
since no change in the actual data is required.

However, I have no idea whether your replication environment would cope
with such a change --- experimenting on a non-production setup would be
highly recommendable.

            regards, tom lane