| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Proposal: Improve bitmap costing for lossy pages |
| Date: | 2017-08-18 03:26:14 |
| Message-ID: | CA+Tgmoa3b-sXMVXDQBqn+3G8VK4yCmteb6CVcOBDSsFBJXKvew@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Aug 17, 2017 at 12:06 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)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
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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