Re: Alter the column data type of the large data volume table.

On Thu, Dec 3, 2020 at 10:18 AM Rich Shepard <rshepard(at)appl-ecosys(dot)com>
wrote:

> Tell me, please, why
>
> ALTER TABLE <tablename> ALTER COLUMN <columnname> SET DATA TYPE BIGINT
>
> will not do the job?
>
> I've found some varchar columns in a couple of tables too small and used
> the
> above to increase their size. Worked perfectly.
>

Something else noteworthy is that with varchar, there is no rewrite of the
table. You are just removing or loosening the length restriction on a
variable width column type. I believe you could change all columns from
VARCHAR(n) to TEXT or VARCHAR(n+X) and have it take almost no time at all
since you are only impacting the catalog tables (pretty sure about that at
least). With a fixed width column like int4 to int8, all the rows need to
be actually re-written.