From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Daniel Farina <daniel(at)heroku(dot)com>, Craig Ringer <ringerc(at)ringerc(dot)id(dot)au>, Harold A(dot) Giménez <harold(dot)gimenez(at)gmail(dot)com> |
Subject: | Re: [PERFORM] DELETE vs TRUNCATE explanation |
Date: | 2012-07-16 19:26:38 |
Message-ID: | CA+TgmoYnqPf03rYJo3G6dMrqShQF2iMtfpYBPgWdxtEdacaX-w@mail.gmail.com |
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On Mon, Jul 16, 2012 at 3:18 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> At any rate, I'm somewhat less convinced that the split was a good
>> idea than I was when we did it, mostly because we haven't really gone
>> anywhere with it subsequently.
>
> BTW, while we are on the subject: hasn't this split completely broken
> the statistics about backend-initiated writes?
Yes, it seems to have done just that. The comment for
ForwardFsyncRequest is a few bricks short of a load too:
* Whenever a backend is compelled to write directly to a relation
* (which should be seldom, if the checkpointer is getting its job done),
* the backend calls this routine to pass over knowledge that the relation
* is dirty and must be fsync'd before next checkpoint. We also use this
* opportunity to count such writes for statistical purposes.
Line 2 seems to have been mechanically changed from "background
writer" to "checkpointer", but of course it should still say
"background writer" in this case.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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