Re: reducing NUMERIC size for 9.1

On 10 July 2010 00:58, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> EnterpriseDB asked me to develop the attached patch to reduce the
> on-disk size of numeric and to submit it for inclusion in PG 9.1.
> After searching the archives, I found a possible design for this by
> Tom Lane based on an earlier proposal by Simon Riggs.

Hi Robert,

I'm reviewing this patch for the commitfest, and so far everything in
the patch looks good. Compile and regression tests worked fine.

However, I was trying to find a simple way to verify that it really
was reducing the on-disk size of compact numeric values and didn't get
the results I was expecting.

I dropped one thousand numerics with value zero into a table and
checked the on-disk size of the relation with your patch and on a
stock 8.4 instance. In both cases the result was exactly the same.

Shouldn't the table be smaller with your patch? Or is there something
wrong with my test?

CREATE TEMP TABLE numeric_short (a numeric);

INSERT INTO numeric_short (a)
SELECT 0::numeric FROM generate_series(1, 1000) i;

Regards,
BJ