Re: automatic analyze: readahead - add "IO read time" log message

From: Stephen Frost <sfrost(at)snowman(dot)net>
To: Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
Cc: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Jakub Wartak <Jakub(dot)Wartak(at)tomtom(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: automatic analyze: readahead - add "IO read time" log message
Date: 2021-01-13 21:17:24
Message-ID: 20210113211724.GF27507@tamriel.snowman.net
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Greetings,

* Stephen Frost (sfrost(at)snowman(dot)net) wrote:
> * Tomas Vondra (tomas(dot)vondra(at)enterprisedb(dot)com) wrote:
> > Thanks. I'll do some testing/benchmarking once my machines are free, in
> > a couple days perhaps. But as I said before, I don't expect this to
> > behave very differently from other places that already do prefetching.
>
> Agreed, but would still be nice to see test results beyond just what
> I've done.

Any chance you were able to run those tests..?

> > FWIW I wonder if this should be tracked separately in the CF app, as
> > it's very different from the original "add some logging" patch, which
> > makes the CF entry rather misleading.
>
> I've gone ahead and updated the CF entry for this to hopefully make it
> clearer for those interested in looking at it. I'll try to come back to
> this in the next CF, ideally we'd at least get someone else to take a
> look at the code beyond me. :) (Obviously, you looked at it some, but
> wasn't really clear if you were alright with it or if you felt it needed
> more review.)

I've updated the patch to leverage Tom's introduction of
TimestatmpDifferenceMilliseconds, which simplifies things a bit (and I
don't think we need to worry about an analyze taking over 25 days...)
and generally rebased this up to current HEAD.

Would be great to get a review / comments from others as to if there's
any concerns. I'll admit that it seems reasonably straight-forward to
me, but hey, I wrote most of it, so that's not really a fair
assessment... ;)

Thanks,

Stephen

Attachment Content-Type Size
analyze_prefetch_v4.patch text/x-diff 11.4 KB

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