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Subject: Re: WAL compression and replica
From: Scott Ribe <scott_ribe@elevated-dev.com>
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 <CAKFQuwYQX9bKp+4GDU+yzB_CkjHiAsft_Y9_Q7L1Q4+v8Ncs7g@mail.gmail.com>
Date: Mon, 25 Mar 2024 14:21:11 -0600
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
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 <CAKFQuwYQX9bKp+4GDU+yzB_CkjHiAsft_Y9_Q7L1Q4+v8Ncs7g@mail.gmail.com>
To: "David G. Johnston" <david.g.johnston@gmail.com>
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 <https://www.postgresql.org/message-id/9435FDA8-261B-4E05-976C-6BB1EBC81815%40elevated-dev.com>
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> On Mar 25, 2024, at 2:17=E2=80=AFPM, David G. Johnston =
<david.g.johnston@gmail.com> wrote:
>=20
> On Mon, Mar 25, 2024 at 1:10=E2=80=AFPM Scott Ribe =
<scott_ribe@elevated-dev.com> wrote:
> If WAL compression is enabled, does this mean that traffic to a =
file-based WAL-shipping standby is compressed? (In other words, WAL =
files are sent post-compression?)
>=20
> =46rom the docs:
> When enabled, the PostgreSQL server compresses full page images =
written to WAL when full_page_writes is on or during a base backup.
>=20
> That is, some of the contents are compressed, it is not the container =
that gets compressed.  That is always 64MB in a default compilation.
>=20
> David J.

I read that last week, and totally missed the implication. Thanks.