Re: Proposal: Improve bitmap costing for lossy pages

Dilip Kumar <dilipbalaut@gmail.com>

From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Alexander Kumenkov <a.kuzmenkov@postgrespro.ru>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-10-06T14:04:16Z
Lists: pgsql-hackers

Attachments

On Fri, Oct 6, 2017 at 7:04 PM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> On Fri, Oct 6, 2017 at 6:36 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Fri, Oct 6, 2017 at 2:12 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
>>>> The performance results look good, but that's a slightly different
>>>> thing from whether the estimate is accurate.
>>>>
>>>> +    nbuckets = tbm_calculate_entires(maxbytes);
>>>>
>>>> entires?
>>>
>>> changed to
>>> + tbm->maxentries = (int) tbm_calculate_entires(maxbytes);
>>
>> My point was not that you should add a cast, but that you wrote
>> "entires" rather than "entries".
>
> My bad, I thought you were suggesting the variable name as "entries"
> instead of "nbuckets" so I removed the variable "nbuckets".  I will
> fix the typo in the function name and post the patch.

Fixed in the attached version.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Account for the effect of lossy pages when costing bitmap scans.