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Re: Bitmap scan cost model (was Re: bitmap scans, btree scans, and tid order) - Mailing list pgsql-hackers

From Manfred Koizar
Subject Re: Bitmap scan cost model (was Re: bitmap scans, btree scans, and tid order)
Date
Msg-id a2dm815pnm26564oeq2bniuhp909pkpfis@email.aon.at
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In response to Bitmap scan cost model (was Re: bitmap scans, btree scans, and tid order)  ("Jeffrey W. Baker" <jwbaker@acm.org>)
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On Tue, 17 May 2005 22:12:17 -0700, "Jeffrey W. Baker" <jwbaker@acm.org>
wrote:
>Incrementing random_page_cost from 4 (the default) to 5 causes the
>planner to make a better decision.

We have such a low default random_page_cost primarily to mask other
problems in the optimizer, two of which are

. multi-column index correlation

. interpolation between min_IO_Cost and max_IO_cost which approximates
max_IO_cost too fast.

ServusManfred

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