Re: [HACKERS] What about LIMIT in SELECT ? - Mailing list pgsql-hackers

From Thomas G. Lockhart
Subject Re: [HACKERS] What about LIMIT in SELECT ?
Date
Msg-id 3626E888.EF4C2139@alumni.caltech.edu
Whole thread Raw
In response to Re: [HACKERS] What about LIMIT in SELECT ?  (Hannu Krosing <hannu@trust.ee>)
List pgsql-hackers
> More seriously, it is not within powers of current regression test
> framework to test speed improvements (only the case where
> performance-wise bad implementation will actually crash the backend,
> as in the cnfify problem, but AFAIK we dont test for those now)

Actually, I keep informal track of run-times for the entire regression
test, which gives me an indication of how things are going. For much of
the v6.4 development, I was seeing runtimes of around 2:30 on my system
(a bit less, a bit more depending on the phase of the moon).

The runtime is currently up at 3:48 (3:40 with egcs-1.1b and
-mpentiumpro rather than the usual gcc-2.7.1 and -m486). I am hoping
that most of that recent increase in runtime is from the recent
additions of Jan's rules and embedded programming language tests.

Although the times aren't directly comparable with older releases (e.g.
we used to have char2,4,8,16 tests and we now have Jan's new tests)
there has been a distinct downward trend in runtimes.

But you're correct in that these timing tests are fairly insensitive to
major improvements in only one query scenerio, since that makes a
relatively small change in the total runtime.

                         - Tom

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