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Message-ID: <5164c593-3fa9-4b1a-9c5f-95d6d5393767@aklaver.com>
Date: Wed, 19 Mar 2025 10:48:39 -0700
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Subject: Re: size of attributes table is too big
To: Siraj G <tosiraj.g@gmail.com>
Cc: pgsql-general@lists.postgresql.org
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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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.klaver@aklaver.com <mailto:adrian.klaver@aklaver.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.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> 

-- 
Adrian Klaver
adrian.klaver@aklaver.com