From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
Cc: | Kevin Grittner <kgrittn(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thom Brown <thom(at)linux(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Steve Singer <steve(at)ssinger(dot)info>, Kevin Grittner <kgrittn(at)ymail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: snapshot too old, configured by time |
Date: | 2016-04-02 12:12:47 |
Message-ID: | CAB7nPqS4X_nqZqW2CCdywWSLk+h_WQoenrwD_PcE9K8UeYUZdA@mail.gmail.com |
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On Fri, Apr 1, 2016 at 11:45 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Kevin Grittner wrote:
>
>> Attached is what I think you're talking about for the first patch.
>> AFAICS this should generate identical executable code to unpatched.
>> Then the patch to actually implement the feature would, instead
>> of adding 30-some lines with TestForOldSnapshot() would implement
>> that as the behavior for the other enum value, and alter those
>> 30-some BufferGetPage() calls.
>>
>> Álvaro and Michael, is this what you were looking for?
>
> Yes, this is what I was thinking, thanks.
A small thing:
$ git diff master --check
src/include/storage/bufmgr.h:181: trailing whitespace.
+#define BufferGetPage(buffer, snapshot, relation, agetest)
((Page)BufferGetBlock(buffer))
- Page page = BufferGetPage(buf);
+ Page page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
Having a BufferGetPageExtended() with some flags and a default
corresponding to NO_SNAPSHOT_TEST would reduce the diff impact. And as
long as the check is integrated with BufferGetPage[Extended]() I would
not complain, the patch as proposed being 174kB...
--
Michael
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