Re: alter table type from double precision to real

On Mon, Jun 25, 2007 at 09:51:30AM +0900, ssoo@siliconfile.com wrote:
> Real type takes 4 byte storage sizes and double precision takes 8 bytes.
> I altered a data type from double precision to real and vacuumed DB.

Altering a column's type rewrites the table so vacuuming afterward
shouldn't be necessary.

> But PostgreSQL's data disk usage did not shrinked.
> And pg_dump size remained same.
> It seems that real takes 8 byte storage sizes.

Real is 4 bytes but other columns' alignment requirements might
result in no space being saved.

--
Michael Fuhr