MIME-Version: 1.0
References: <CAG8xnif_jmRYAGUvtoQNsHA8UqGRDkwuSffO55-3wGMLQArA8g@mail.gmail.com>
 <CAKFQuwbudVTMKedFTuR+GXntRM=oZ=sCgyp1Ztg2=DUciuEbQA@mail.gmail.com>
 <729685.1769572320@sss.pgh.pa.us> <CANzqJaCydWJm8utvhLMWy62MGRYP0qdK134WB8NzXTJf=KUEPg@mail.gmail.com>
 <731539.1769573201@sss.pgh.pa.us> <CAJ7S9TWwFpaRD9eND1=GMmCoKPG4fDasU6LBEd=yaq2JyNqRdA@mail.gmail.com>
In-Reply-To: <CAJ7S9TWwFpaRD9eND1=GMmCoKPG4fDasU6LBEd=yaq2JyNqRdA@mail.gmail.com>
From: Gus Spier <gus.spier@gmail.com>
Date: Wed, 28 Jan 2026 05:57:09 -0500
Message-ID: <CAG8xnie28cnR7220M8G3iQ0G-L_c3WOp6ZrSOiP58M3-B=6-Zw@mail.gmail.com>
Subject: Re: Attempting to delete excess rows from table with BATCH DELETE
To: Olivier Gautherot <ogautherot@gautherot.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Ron Johnson <ronljohnsonjr@gmail.com>, 
	"David G. Johnston" <david.g.johnston@gmail.com>, 
	pgsql-general <pgsql-general@lists.postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://www.postgresql.org/message-id/CAG8xnie28cnR7220M8G3iQ0G-L_c3WOp6ZrSOiP58M3-B%3D6-Zw%40mail.gmail.com>
Precedence: bulk

Thanks to all.

I'll give the bash loop method a try and let you know how it works out.

Regards to all,
Gus


On Wed, Jan 28, 2026 at 2:32=E2=80=AFAM Olivier Gautherot
<ogautherot@gautherot.net> wrote:
>
> Hi Gus!
>
> This reminds me of a costly mistake I made and you want to avoid: it was =
a mission critical database (say physical safety, real people) and the vacu=
um froze the DB for 24 hours, until I finally took it offline.
>
> If you can take it offline (and you have a couple of hours)
> - disconnect the DB
> - drop indexes (that's the killer)
> - remove unnecessary data
> - vaccuum manually (or better, copy the relevant data to a new table and =
rename it - this will save the DELETE above and will defragment the table)
> - rebuild indexes
> - connect the DB
>
> The better solution would be partitioning:
> - choose a metrics (for instance a timestamp)
> - create partition tables for the period you want to keep
> - copy the relevant data to the partitions and create partial indexes
> - take the DB off line
> - update the last partition with the latest data (should be a fast update=
)
> - truncate the original table
> - connect partitions
> - connect the DB
>
> In the future, deleting historic data will be a simple DROP TABLE.
>
> Hope it helps
> --
> Olivier Gautherot
> Tel: +33 6 02 71 92 23
>
>
> El mi=C3=A9, 28 de ene de 2026, 5:06=E2=80=AFa.m., Tom Lane <tgl@sss.pgh.=
pa.us> escribi=C3=B3:
>>
>> Ron Johnson <ronljohnsonjr@gmail.com> writes:
>> > Hmm.  Must have been START TRANSACTION which I remember causing issues=
 in DO
>> >  blocks.
>>
>> Too lazy to test, but I think we might reject that.  The normal rule
>> in a procedure is that the next command after a COMMIT automatically
>> starts a new transaction, so you don't need an explicit START.
>>
>>                         regards, tom lane
>>
>>