Re: Result Cache node shows per-worker info even for workers not launched - Mailing list pgsql-hackers

From Amit Khandekar
Subject Re: Result Cache node shows per-worker info even for workers not launched
Date
Msg-id CAJ3gD9d_ZqercSJQKF6rKz+5huxUBhrYFsXNxyZ5158GY7F+5w@mail.gmail.com
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In response to Re: Result Cache node shows per-worker info even for workers not launched  (Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>)
List pgsql-hackers
On Wed, 28 Apr 2021 at 15:08, Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Wed, Apr 28, 2021 at 1:54 PM David Rowley <dgrowleyml@gmail.com> wrote:
> > I plan to push this in the next 24 hours or so.
>
> I happen to see explain_resultcache in resultcache.sql, seems like two
> of the tests still have numbers for cache hits and misses - Hits: 980
> Misses: 20, won't these make tests unstable? Will these numbers be
> same across machines? Or is it that no buildfarm had caught these? The
> comment below says that, the hits and misses are not same across
> machines:
> -- Ensure we get some evictions.  We're unable to validate the hits and misses
> -- here as the number of entries that fit in the cache at once will vary
> -- between different machines.
>
> Should we remove the hide_hitmiss parameter in explain_resultcache and
> always print N for non-zero and Zero for 0 hits and misses? This
> clearly shows that we have 0 or non-zero hits or misses.
>
> Am I missing something?

I believe, the assumption here is that with no workers involved, it is
guaranteed to have the exact same cache misses and hits anywhere.



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