| From: | KAWAMICHI Ryoji <kawamichi(at)tkl(dot)iis(dot)u-tokyo(dot)ac(dot)jp> |
|---|---|
| To: | Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Erroneous cost estimation for nested loop join |
| Date: | 2015-11-12 08:21:51 |
| Message-ID: | 1696266773.13042205.1447316511952.JavaMail.zimbra@tkl.iis.u-tokyo.ac.jp |
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| Lists: | pgsql-hackers |
<GavinFlower(at)archidevsys(dot)co(dot)nz> wrote:
>
> More knowledgeable people are sure to reply in more detail!
>
> However, they would probably appreciate it if you can run with 9.4.5
> (the latest released version). Running it with the beta of 9.5 would be
> a bonus!
>
> Note that I don't know enough to say for sure that later versions would
> make any difference in this case, but at least using later later
> versions would kill lots of Red Herrings! :-)
>
Difference between minor versions does not matter in this case. I confirmed
the cost calculation logic regarding this problem was not changed between
Postgres 9.4.1 and 9.4.5.
I heard there are some performance improvements on 9.5. It might change
something regarding this problem. so I will try these queries on 9.5!
Thanks
Ryoji
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