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From: Kyotaro Horiguchi <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: Improve WALRead() to suck data directly from WAL buffers when possible
Date: Mon, 12 Dec 2022 12:06:36 +0900 (JST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CALj2ACXKKK=wbiG5_t6dGao5GoecMwRkhr7GjVBM_jg54+Na=Q@mail.gmail.com>
	<[email protected]>

At Mon, 12 Dec 2022 11:57:17 +0900 (JST), Kyotaro Horiguchi <[email protected]> wrote in 
> This patch copies the bleeding edge WAL page without recording the
> (next) insertion point nor checking whether all in-progress insertion
> behind the target LSN have finished. Thus the copied page may have
> holes.  That being said, the sequential-reading nature and the fact
> that WAL buffers are zero-initialized may make it work for recovery,
> but I don't think this also works for replication.

Mmm. I'm a bit dim. Recovery doesn't read concurrently-written
records. Please forget about recovery.

> I remember that the one of the advantage of reading the on-memory WAL
> records is that that allows walsender to presend the unwritten
> records. So perhaps we should manage how far the buffer is filled with
> valid content (or how far we can presend) in this feature.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center





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