Re: mosbench revisited - Mailing list pgsql-hackers

From Tom Lane
Subject Re: mosbench revisited
Date
Msg-id 22145.1312400330@sss.pgh.pa.us
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In response to Re: mosbench revisited  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: mosbench revisited
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Robert Haas <robertmhaas@gmail.com> writes:
> On a straight pgbench -S test, you get four system calls per query:
> recvfrom(), lseek(), lseek(), sendto().  Adding -M prepared eliminates
> the two lseeks.

[ scratches head... ]  Two?  Is that one for the table and one for its
lone index, or are we being redundant there?

(If the query ended up being a seqscan, I'd expect a second
lseek(SEEK_END) when the executor starts up, but I gather from the other
complaints that the mosbench people were only testing simple indexscan
queries.)
        regards, tom lane


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