Re: New vacuum option to do only freezing

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: New vacuum option to do only freezing
Date: 2018-11-01 17:01:55
Message-ID: CA+TgmoZQ_sLvsmTG251+i_Y-v3AARJ0FAy2dUH4DgL3p8xsgrw@mail.gmail.com
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On Mon, Oct 1, 2018 at 6:23 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> Attached patch adds a new option FREEZE_ONLY to VACUUM command. This
> option is same as FREEZE option except for it disables reclaiming dead
> tuples. That is, with this option vacuum does pruning HOT chain,
> freezing live tuples and maintaining both visibility map and freespace
> map but does not collect dead tuples and invoke neither heap vacuum
> nor index vacuum. This option will be useful if user wants to prevent
> XID wraparound a table as quick as possible, especially when table is
> quite large and is about to XID wraparound. I think this usecase was
> mentioned in some threads but I couldn't find them.

The feature seems like a reasonable one, but the name doesn't seem
like a good choice. It doesn't only freeze - e.g. it HOT-prunes, as
it must. Maybe consider something like (without_index_cleanup true)
or (index_cleanup false).

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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