Re: Risk Estimation WAS: Planner hints in Postgresql - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Risk Estimation WAS: Planner hints in Postgresql
Date
Msg-id 4472.1395328870@sss.pgh.pa.us
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In response to Re: Risk Estimation WAS: Planner hints in Postgresql  (Atri Sharma <atri.jiit@gmail.com>)
Responses Re: Risk Estimation WAS: Planner hints in Postgresql  (Atri Sharma <atri.jiit@gmail.com>)
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Atri Sharma <atri.jiit@gmail.com> writes:
> Now, why cannot we take the estimate of all the buckets behind the bucket
> in which our value is present? Will that estimate not give us the fraction
> of tuples that are expected to be before the first matching row?

Uh, no, not unless you assume that the table happens to be perfectly
sorted by the column's value.
        regards, tom lane



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