Re: Estimating seq_page_fetch and random_page_fetch - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Estimating seq_page_fetch and random_page_fetch
Date
Msg-id 8589.1173372468@sss.pgh.pa.us
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In response to Estimating seq_page_fetch and random_page_fetch  ("Umar Farooq Minhas" <umarfm13@hotmail.com>)
Responses Re: Estimating seq_page_fetch and random_page_fetch  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-hackers
"Umar Farooq Minhas" <umarfm13@hotmail.com> writes:
> How can we accrately estimate the "seq_page_fetch" and =
> "random_page_fetch" costs from outside the postgres using for example a =
> C routine.

Use a test case larger than memory.  Repeat many times to average out
noise.  IIRC, when I did the experiments that led to the current
random_page_cost of 4.0, it took about a week before I had numbers I
trusted.
        regards, tom lane


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