From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Erik Rijkers <er@xs4all.nl>
Cc: Kevin Grittner <kgrittn@mail.com>
Cc: pgsql-hackers@postgresql.org, Andres Freund <andres@2ndquadrant.com>
Subject: Re: foreign key locks
Date: Fri, 18 Jan 2013 15:37:47 -0500
Message-ID: <28623.1358541467@sss.pgh.pa.us> (raw)
In-Reply-To: <20130118200204.GH4063@alvh.no-ip.org>
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Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> The reason is that there is an (unknown to me) rule that there must be
> some data not associated with a buffer:
> /*
> * NOTE: We disallow len == 0 because it provides a useful bit of extra
> * error checking in ReadRecord. This means that all callers of
> * XLogInsert must supply at least some not-in-a-buffer data. [...]
> */
> This seems pretty strange to me. And having the rule be spelled out
> only in a comment within XLogInsert and not at its top, and not nearby
> the XLogRecData struct definition either, seems pretty strange to me.
> I wonder how come every PG hacker except me knows this.
I doubt it ever came up before. What use is logging only the content of
a buffer page? Surely you'd need to know, for example, which relation
and page number it is from.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, alvherre@2ndquadrant.com, er@xs4all.nl, kgrittn@mail.com, andres@2ndquadrant.com
Subject: Re: foreign key locks
In-Reply-To: <28623.1358541467@sss.pgh.pa.us>
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