Re: system usage stats (Was: Re: Why Not MySQL? ) - Mailing list pgsql-hackers

From Tom Lane
Subject Re: system usage stats (Was: Re: Why Not MySQL? )
Date
Msg-id 22741.957419252@sss.pgh.pa.us
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In response to Re: system usage stats (Was: Re: Why Not MySQL? )  (The Hermit Hacker <scrappy@hub.org>)
Responses Re: system usage stats (Was: Re: Why Not MySQL? )
List pgsql-hackers
The Hermit Hacker <scrappy@hub.org> writes:
> Now, Mitch's results for v7.0 showed something like:
> 0/12 filesystem blocks in/out
> You intepreted that as 12 reads from the file system ... 'out' I would
> have interpreted as writes to the file system, which made zero sense
> ... do we have our 'in/out's backwards here?

Good point.  Writes from a SELECT are certainly possible --- the SELECT
could be writing tuple status-flag updates, if it was the first
transaction to verify commit status of tuples created by a prior
transaction.  But that again raises the issue of whether we've got
a fair comparison.  The 6.5 test apparently only saw already-marked-
committed tuples ...
        regards, tom lane


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