From: | Daniel Gustafsson <daniel(at)yesql(dot)se> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de>, Justin Pryzby <pryzby(at)telsasoft(dot)com> |
Cc: | Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: should INSERT SELECT use a BulkInsertState? |
Date: | 2020-07-12 20:04:21 |
Message-ID: | 1C04654B-C4F8-4E2D-A636-6AC5799A86AB@yesql.se |
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Lists: | pgsql-hackers |
> On 4 Jun 2020, at 19:30, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2020-05-08 02:25:45 -0500, Justin Pryzby wrote:
>> Seems to me it should, at least conditionally. At least if there's a function
>> scan or a relation or ..
>
> Well, the problem is that this can cause very very significant
> regressions. As in 10x slower or more. The ringbuffer can cause constant
> XLogFlush() calls (due to the lsn interlock), and the eviction from
> shared_buffers (regardless of actual available) will mean future vacuums
> etc will be much slower. I think this is likely to cause pretty
> widespread regressions on upgrades.
>
> Now, it sucks that we have this problem in the general facility that's
> supposed to be used for this kind of bulk operation. But I don't really
> see it realistic as expanding use of bulk insert strategies unless we
> have some more fundamental fixes.
Based on the above, and the lack of activity in the thread, it sounds like this
patch should be marked Returned with Feedback; but Justin: you set it to
Waiting on Author at the start of the commitfest, are you working on a new
version?
cheers ./daniel
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