Message-ID: <51111525fb84ecdadaf99c13a2fa63e4be08041e.camel@j-davis.com>
Subject: Re: LogwrtResult contended spinlock
From: Jeff Davis <pgsql@j-davis.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Tom Lane
 <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>,
 pgsql-hackers@lists.postgresql.org, Jaime Casanova
 <jcasanov@systemguards.com.ec>
Date: Sun, 07 Apr 2024 12:47:00 -0700
In-Reply-To: <202404071219.p5qphx7vzxte@alvherre.pgsql>
References: <202404071219.p5qphx7vzxte@alvherre.pgsql>
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On Sun, 2024-04-07 at 14:19 +0200, Alvaro Herrera wrote:
> I pushed the "copy" pointer now, except that I renamed it to
> "insert",
> which is what we call the operation being tracked.=C2=A0 I also added som=
e
> comments.

The "copy" pointer, as I called it, is not the same as the "insert"
pointer (as returned by GetXLogInsertRecPtr()).

LSNs before the "insert" pointer are reserved for WAL inserters (and
may or may not have made it to WAL buffers yet). LSNs before the "copy"
pointer are written to WAL buffers with CopyXLogRecordToWAL() (and may
or may not have been evicted to the OS file yet).

Other than that, looks good, thank you.

Regards,
	Jeff Davis