Re: [PATCH] XLogReadRecord returns pointer to currently read page

From: Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>
To: Michael Paquier <michael(at)paquier(dot)xyz>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
Cc: hlinnaka(at)iki(dot)fi, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PATCH] XLogReadRecord returns pointer to currently read page
Date: 2018-11-19 05:48:06
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On 16.11.2018 11:23, Michael Paquier wrote:
> On Thu, Nov 15, 2018 at 06:12:38PM +0900, Kyotaro HORIGUCHI wrote:
>> This patch eliminates unnecessary copying that was done for
>> non-continued records. Now the return value of XLogReadRecord
>> directly points into page buffer holded in XLogReaderStats. It is
>> safe because no caller site uses the returned pointer beyond the
>> replacement of buffer content at the next call to the same
>> function.
> I was looking at this patch, and shouldn't we worry about compatibility
> with plugins or utilities which look directly at what's in readRecordBuf
> for the record contents? Let's not forget that the contents of
> XLogReaderState are public.

According to my experience, I clarify some comments to avoid this
mistakes in the future (see attachment).

Andrey Lepikhov
Postgres Professional
The Russian Postgres Company

Attachment Content-Type Size
0001-Some-clarifications-on-readRecordBuf-comments.patch text/x-patch 1.7 KB

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