Re: Proposal: Improve bitmap costing for lossy pages

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
Cc: Alexander Kumenkov <a(dot)kuzmenkov(at)postgrespro(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal: Improve bitmap costing for lossy pages
Date: 2017-10-05 14:45:52
Message-ID: CA+Tgmoa7hxMBDVmWSajs4DjqXGtKvCQUqrAbEe9m8ZOxqJSsag@mail.gmail.com
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On Sun, Sep 17, 2017 at 7:04 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> I used lossy_pages = max(0, total_pages - maxentries / 2). as
> suggesed by Alexander.

Does that formula accurately estimate the number of lossy pages?

The performance results look good, but that's a slightly different
thing from whether the estimate is accurate.

+ nbuckets = tbm_calculate_entires(maxbytes);

entires?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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