Re: How to do faster DML

On 2/15/24 08:16, Greg Sabino Mullane wrote:
> So as I also tested the same as you posted, there has been no change
> in "ctid" , when I altered the column data type from 'int' to
> 'bigint' in the table, so that means full table rewriting
> won't happen in such a scenario.
>
>
> No it was definitely rewritten - do not depend on the ctid to verify
> that. Take our word for it, or
> use*pg_relation_filenode('int_test');* before and after, as well as
> *pg_relation_size('int_test')*;

That is a mixed bag:

test=# select pg_relation_filenode('int_test');
pg_relation_filenode
----------------------
69999
(1 row)

test=# select pg_relation_size('int_test');
pg_relation_size
------------------
368640
(1 row)

test=# alter table int_test alter column int_fld set data type bigint;
ALTER TABLE
test=# select pg_relation_filenode('int_test');
pg_relation_filenode
----------------------
70002
(1 row)

test=# select pg_relation_size('int_test');
pg_relation_size
------------------
368640

>
> Cheers,
> Greg
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com