Re: size of attributes table is too big

On 3/19/25 10:36 AM, Siraj G wrote:
> Hi Adrian
>
> Used this query to find the sizes:
>
> select  relname AS object_name,relkind AS
> object_type,pg_size_pretty(pg_relation_size(oid)) AS object_size
> FROM pg_class WHERE relnamespace = (SELECT oid FROM pg_namespace WHERE
> nspname = 'pg_catalog')
> ORDER BY pg_relation_size(oid) DESC;
>
> We have close to 2000 tables, not sure about the columns. There should
> be around 120 - 150 tables that are active, getting the data from DMS.

This would have been a good thing to have included in the original post.

> We do not create/drop tables in our instance unless required.
>
> This is a cloud managed SQL and we do not have any custom setting on the
> vacuum part.

To be clear the issue is in the Google Cloud SQL instance?

Or are you seeing the problem on the Postgres instance the data is
coming from?

>
> On Wed, Mar 19, 2025 at 10:47 PM Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>> wrote:
>
> On 3/19/25 10:06, Siraj G wrote:
> > Hello!
> >
> > I have a PG (v16) instance which is occupying around 1TB of
> storage. Out
>
> Exact version of Postgres 16, include the x in 16.x.
>
> > of this, around 350GB is occupied by the table
> pg_catalog.pg_attribute.
> > Why is the catalog table's size so big?
> >
> > Here are the sizes:
>
> How did you measure the sizes?
>
> pg_attribute maintains information about table columns, how many table
> columns do you have?
>
> Are you creating/dropping tables on a regular basis?
>
> Is autovacuum running properly?
>
> Have you run VACUUM manually on pg_attribute?
>
> >
> > pg_attribute
> >
> > 338 GB
> > pg_attribute_relid_attnam_index
> >
> > 117 GB
> > pg_attribute_relid_attnum_index
> >
> > 69 GB
> >
> >
> > I think this table must have tons of dead tuples. Please suggest
> to me
> > if we can purge any data/shrink the size of this table.
> >
> > REgards
> > Siraj
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>

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