Re: Gather Merge

On Fri, Feb 17, 2017 at 3:59 PM, Thomas Munro
<thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> On Thu, Feb 2, 2017 at 2:32 AM, Rushabh Lathia <rushabh(dot)lathia(at)gmail(dot)com> wrote:
>> Please find attached latest patch.
>
> The latest patch still applies (with some fuzz), builds and the
> regression tests pass.
>
> I see that Robert made a number of changes and posted a v6 along with
> some numbers which he described as lacklustre, but then fixed a row
> estimate problem which was discouraging parallel joins (commit
> 0c2070ce). Rushabh posted a v7 and test results which look good.
>

Are you suggesting that commit 0c2070ce has helped to improve
performance if so, I don't think that has been proved? I guess the
numbers are different either due to different m/c or some other
settings like scale factor or work_mem.

> As
> far as I can see there are no outstanding issues or unhandled review
> feedback. I've had a fresh read through of the latest version and
> have no further comments myself.
>
> I've set this to ready-for-committer now. If I've misunderstood and
> there are still unresolved issues from that earlier email exchange or
> someone else wants to post a review or objection, then of course
> please feel free to set it back.
>
> BTW There is no regression test supplied. I see that commit 5262f7a4
> adding parallel index scans put simple explain output in
> "select_parallel" to demonstrate the new kind of plan being created;

It has added both explain statement test and a test to exercise
parallel index scan code.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com