| From: | "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com> |
|---|---|
| To: | 'Amit Langote' <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
| Cc: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | RE: speeding up planning with partitions |
| Date: | 2019-01-21 00:51:53 |
| Message-ID: | 0F97FA9ABBDBE54F91744A9B37151A5125964E@g01jpexmbkw24 |
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| Lists: | pgsql-hackers |
Tsunakawa-san
On Thu, Jan 18, 2019 at 5:29 AM, Amit Langote wrote:
> On 2019/01/18 14:12, Tsunakawa, Takayuki wrote:
...
> > Isn't CheckCachedPlan() (and AcquireExecutorLocks() therein) called
> in every EXECUTE after 6th one due to some unknow issue?
>
> CheckCachedPlan is only called if choose_custom_plan() returns false
> resulting in generic plan being created/reused. With plan_cache_mode
> = auto, I see it always returns true, because a custom plan containing
> a single partition to scan is way cheaper than the generic plan.
>
> > Does choose_custom_plan() always return true after 6th EXECUTE?
>
> Yes.
Yes.
I also checked choose_custom_plan() always returns true excluding 6th EXECUTE
and CheckCachedPlan() is only called at 6th EXECUTE.
Yoshikazu Imai
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