From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Bossart, Nathan <bossartn@amazon.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: andres@anarazel.de <andres@anarazel.de>
Cc: masao.fujii@oss.nttdata.com <masao.fujii@oss.nttdata.com>
Cc: pgsql-hackers@lists.postgresql.org <pgsql-hackers@lists.postgresql.org>
Cc: mengjuan.cmj@alibaba-inc.com <mengjuan.cmj@alibaba-inc.com>
Cc: Jakub.Wartak@tomtom.com <Jakub.Wartak@tomtom.com>
Subject: Re: prevent immature WAL streaming
Date: Fri, 17 Sep 2021 17:31:34 -0300
Message-ID: <202109172031.67v345vxyano@alvherre.pgsql> (raw)
In-Reply-To: <BB4ED267-90F1-4370-A5E1-B66A7A8D62FC@amazon.com>
On 2021-Sep-17, Bossart, Nathan wrote:
> I gave the patch a read-through. I'm wondering if the
> XLOG_OVERWRITE_CONTRECORD records are actually necessary. IIUC we
> will set XLP_FIRST_IS_ABORTED_PARTIAL on the next page, and
> xlp_pageaddr on that page will already be validated in
> XLogReaderValidatePageHeader(). Does adding this new record also help
> ensure the page header is filled in and flushed to disk?
That was the first implementation, a few versions of the patch ago. An
added benefit of a separate WAL record is that you can carry additional
data for validation, such as -- as suggested by Andres -- the CRC of the
partial data contained in the message that we're skipping. I didn't
implement that, but it should be trivial to add it.
--
Álvaro Herrera 39°49'30"S 73°17'W — https://www.EnterpriseDB.com/
"How strange it is to find the words "Perl" and "saner" in such close
proximity, with no apparent sense of irony. I doubt that Larry himself
could have managed it." (ncm, http://lwn.net/Articles/174769/)
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To: pgsql-hackers@postgresql.org
Cc: alvherre@alvh.no-ip.org, bossartn@amazon.com, horikyota.ntt@gmail.com, andres@anarazel.de, masao.fujii@oss.nttdata.com, pgsql-hackers@lists.postgresql.org, mengjuan.cmj@alibaba-inc.com, Jakub.Wartak@tomtom.com
Subject: Re: prevent immature WAL streaming
In-Reply-To: <202109172031.67v345vxyano@alvherre.pgsql>
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