Re: Re: JDBC Performance

On Tue, 10 Oct 2000, Keith L. Musser wrote:

> jdbc7.0-1.2.jar                  1.89 ms    5.0 ms     3.9 ms
> postgresql.jar (191450 bytes)    1.36 ms    3.1 ms     3.2 ms
> postgresql.jar (204223 bytes)    1.78 ms    3.9 ms     4.1 ms
>
> In Test #2 w/ GC, I purposefully ran System.gc() every 150 msec during
> the test.  This reduces my dependence on how often I create and free
> objects.  It also made the original driver faster than the new one.
>
> The times depend significantly on what I do in my program -- if I
> cache results, I can see execution times slow down significantly
> (sometimes slower by a factor of 20!).  (The numbers above are with
> the cache turned OFF.)  That's why I'm running the GC frequently; with
> it, I get consistently good times.
>
> The two versions of postgresql.jar are both less sensitive to memory
> allocation in my part of the program.  That is, the times do no grow
> when I use a cache with these drivers.
>
> I conclude the following: -----------------------------

> (1) the older postgresql.jar is faster than the newer one (the 191450
> byte version is older).  I don't know what's the difference; I didn't
> every realize I had two different versions until this morning.

jdbc7.0-1.2.jar is the 7.0.0 driver, so has none of Gunnar's optimisations
in it, so it suffers a lot from a lot of allocations.

Peter

--
Peter T Mount peter@retep.org.uk http://www.retep.org.uk
PostgreSQL JDBC Driver http://www.retep.org.uk/postgres/
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