Re: Proposal: Improve bitmap costing for lossy pages

On Thu, Aug 17, 2017 at 12:06 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> I have attempted a very simple POC with this approach just to see how
> many lossy pages we can save if we lossify all the pages falling in
> the same chunk first, before moving to the next page.  I have taken
> some data on TPCH scale 20 with different work_mem (only calculated
> lossy pages did not test performance).  I did not see a significant
> reduction in lossy pages.  (POC patch attached with the mail in case
> someone is interested to test or more experiment).

That's not an impressive savings.  Maybe this approach is a dud, and
we should go back to just tackling the planner end of it.

-- 
Robert Haas
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