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From Knut Anders Hatlen <Knut.Hat...@Sun.COM>
Subject Re: Performance Tuning Problem ?
Date Sat, 23 May 2009 09:39:41 GMT
ganest <ganest@ced.tuc.gr> writes:

> I am executing using ij tool (java -Dderby.language.maxMemoryPerTable=4096
> -Xms256m -Xmx256m -jar $DERBY_HOME/lib/derbyrun.jar ij) 
> the following query: (I read about derby.language.maxMemoryPerTable in this
> mailing list)
>
> select count(*) from  big inner join bigref on big.id=bigref.bigid and
> big.name like '0ff%';
>
> The result is: 258 and it takes more than 20 seconds to be executed. Using
> mysql with the same
> configuration the result is produced in milliseconds.

For the record, I ran the code you provided on my machine, using only
the default settings for Derby and the JVM, and I see that the query
takes less than 150 ms:

ij> elapsedtime on;
ij> select count(*) from  big inner join bigref on big.id=bigref.bigid and big.name like
'0ff%'; 
1          
-----------
255        

1 row selected
ELAPSED TIME = 133 milliseconds

This is with head of the Derby 10.5 branch, OpenSolaris 2009.06 snv_111a
X86, and

java version "1.6.0_13"
Java(TM) SE Runtime Environment (build 1.6.0_13-b03)
Java HotSpot(TM) Server VM (build 11.3-b02, mixed mode)

The runtime statistics on my machine are almost identical to the ones
you provided (some small differences in page count and row count due to
the randomness of the code that populates the tables).

-- 
Knut Anders

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