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help / color / mirror / Atom feedFrom: Michael Christofides <[email protected]>
To: Laurenz Albe <[email protected]>
Cc: Vik Fearing <[email protected]>
Cc: David Rowley <[email protected]>
Cc: Guillaume Lelarge <[email protected]>
Cc: Greg Sabino Mullane <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: David G. Johnston <[email protected]>
Cc: Nikolay Samokhvalov <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: [email protected]
Subject: Re: Proposals for EXPLAIN: rename ANALYZE to EXECUTE and extend VERBOSE
Date: Mon, 2 Dec 2024 11:41:48 +0000
Message-ID: <CAFwT4nAOYtV5spHacjXHA591_m1Rr0LwT7F_YQbrHwRB4FjV0Q@mail.gmail.com> (raw)
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> v4 patch attached
Thank you Guillaume, and nice work! I tried to see if there was anywhere
else in the documentation that would need updating, but it looks like you
covered everywhere already.
> I'm with Robert in that I've not found the buffer counts to be all that
useful most of the time.
I find the buffer counts especially helpful for educating newer folks on
why things are slow, even when they are not necessary for spotting the
issue (for more advanced users). One of my hopes is that by educating and
empowering newer users on how I/O relates to performance issues, fewer
cases will get escalated to more experienced folks.
> the cases I've seen most recently are those where the output is
mind-numbingly long already.
Are you mostly seeing query plans that have stumped other people already
(eg second or third line support), so perhaps seeing more complex plans
than the average user?
Both Depesz[1] and Tensor[2] have archives of publicly submitted plans,
which I found helpful for checking how slow plans look for users of those
tools. I have a similar archive, and while we do not publish them (and
there are plenty of huge plans) it also suggests that the majority of slow
plans people are reviewing have fewer than 20 nodes.
I realise it’s optimistic to think that the time experienced hackers would
lose having to sift through longer plans would be gained back by having to
do so less often, but I thought it was worth raising as part of the aim.
I also looked into the Slow Query Questions page on the wiki that we ask
people to review before posting to pgsql-performance, and noticed that has
suggested requesting buffers for the past 12 years[3].
—
Michael
[1]: https://explain.depesz.com/history
[2]: https://explain.tensor.ru/archive
[3]:
https://wiki.postgresql.org/index.php?title=Slow_Query_Questions&diff=18308&oldid=16800
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Subject: Re: Proposals for EXPLAIN: rename ANALYZE to EXECUTE and extend VERBOSE
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