| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: pgsql: Charge cpu_tuple_cost * 0.5 for Append and MergeAppend nodes. |
| Date: | 2018-02-22 13:31:30 |
| Message-ID: | CA+TgmoZVzjk-6dxQ1gHhhsT7Re3t=gmWB9_zoHrqxtO74W0M2w@mail.gmail.com |
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| Lists: | pgsql-committers pgsql-hackers |
On Thu, Feb 22, 2018 at 12:35 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <rhaas(at)postgresql(dot)org> writes:
>> Charge cpu_tuple_cost * 0.5 for Append and MergeAppend nodes.
>
> This seems to have produced some plan instability in the buildfarm.
I was worried about that. Looking at it now. I wish we had some way
to figure out whether a given plan was likely to be unstable on the
buildfarm other than committing it and seeing what happens. It's
surprisingly difficult to write non-trivial tests that produce
consistent EXPLAIN output, and annoyingly time-consuming to try to
figure out why they don't.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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