I don't have any clues.
While most of our work happens on Linux, we do measure performance on
Windows from one release to the next (see for example item 23-b on the
most recent release check-list
https://www.sqlite.org/checklists/private/3081100/index#c23) and it
gets better from one release to the next. So I don't know why you are
seeing a slowdown.
How do you measure?
On 8/24/15, Jakub Zakrzewski <jzakrzewski at e2e.ch> wrote:
> Hi All,
>
> I finally got a chance to upgrade SQLite for our product from ancient
> 3.7.16.2. Initial tests on Linux were very promising - ranging from 33% to
> even 300% (for one degenerated case) speed improvement. So far so good.
> Problems begun when I have tested it on Windows. Depending on test case the
> new version is up to 0.28x slower! In the course of investigation I have
> managed to improve the performance by adding few missing indexes but this
> has influenced both old and new versions so the relative performance with
> 3.8.11.1 is still like one third worse.
>
> I have tried doing it step-by-step: 3.7.16.2 -> 3.7.17.0 -> 3.8.0.0 and the
> results are quite surprising:
> 3.7.16.2 -> 3.7.17.0 : ~16% faster
> 3.7.17.0 -> 3.8.0.0 : ~26% slower
> 3.7.16.2 -> 3.8.0.0 : ~15% slower
> 3.7.16.2 -> 3.8.11.1 : ~28% slower
>
> We use SQLite as backend ("persistent storage") to an implementation of a
> state machine. The queries are rather simple and each of them is too fast to
> measure (SQLite performance timer only has resolution of milliseconds) in
> the profiler it looks like the actual filesystem functions were taking more
> time in new versions but that tells me nothing really.
>
> Is there something I can tweak?
> The page size is set to 4K (NTFS file system), synchonous is OFF,
> journal_mode=truncated;
>
> With 10K objects all versions seem to perform equally: test takes ~45s. For
> 100K objects it's already [m]:[s]
> 3.7.16.2 : ~10:55
> 3.7.17.0 : ~09:30
> 3.8.0.0 : ~12:46
> 3.8.11.1 : ~15:08
>
> I'm out of ideas here. Can someone help me with further investigation?
>
> --
> Gruesse,
> Jakub
>
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>
--
D. Richard Hipp
drh at sqlite.org
