Re: relpages of btree indexes are not truncating even after deleting all the tuples from table and doing vacuum

From: Mahendra Singh <mahi6run(at)gmail(dot)com>
To: Peter Geoghegan <pg(at)bowt(dot)ie>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: relpages of btree indexes are not truncating even after deleting all the tuples from table and doing vacuum
Date: 2019-12-25 05:02:07
Message-ID: CAKYtNArA8kEfsHKhkogk026rbewAL7RtKuF8VSdXWUm+QY5zmw@mail.gmail.com
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On Tue, 24 Dec 2019 at 02:41, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
>
> On Mon, Dec 23, 2019 at 11:05 AM Mahendra Singh <mahi6run(at)gmail(dot)com> wrote:
> > From above example, we can see that after deleting all the tuples from table and firing vacuum command, size of table is reduced but size of index relation is same as before vacuum.
>
> VACUUM is only able to make existing empty pages in indexes recyclable
> by future page splits within the same index. It is not possible for it
> to reclaim space for the filesystem. Workload characteristics tend to
> determine whether or not this limitation is truly important.

Thank you for the clarification.

Thanks and Regards
Mahendra Singh Thalor
EnterpriseDB: http://www.enterprisedb.com

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