Re: alter table type from double precision to real - Mailing list pgsql-general

Actually, table size shrinked a little.
But I misinterpreted it as no shrinking.
I expected much more shrinking.

Thank you for your concerns.

Michael Fuhr <mike@fuhr.org> wrote:
> I see table sizes shrink on 64-bit sparc and x86 architectures, as
> in the following example that results in adjacent 4-byte columns.
> Or am I misinterpreting what's happening?
>
> test=> create table test (col1 double precision, col2 integer);
> CREATE TABLE
> test=> insert into test select 1.0, 1 from generate_series(1, 10000);
> INSERT 0 10000
> test=> select pg_relation_size('test');
>  pg_relation_size
> ------------------
>            524288
> (1 row)
>
> test=> alter table test alter col1 type real;
> ALTER TABLE
> test=> select pg_relation_size('test');
>  pg_relation_size
> ------------------
>            450560
> (1 row)