Read-only and multi threading

[Guillaume]

Hello, 

I have a database (approx. 2200 tables with 500 lines each, 50Mb) that need to be accessed by several threads (4 or 6 for example). There is a lot of calculations to do on this database and it takes about 15 hours, so it needs to be very fast.

I already tried read-only mode with multi threading (MULTI_THREADED=TRUE, ACCESS_MODE_DATA=r) as threads only read the data and write the result in an other database.

But is there other ways to improve performances ? For example, I think there is no need to "lock" the database as it is read only (but maybe I misunderstood something here). Should I use FILE_LOCK=NO or LOCK_MODE=0 ? (actually using lock_mode=0 in the url throw an error n° 90133 CANNOT_CHANGE_SETTING_WHEN_OPEN).

Is there any other way to improve reading performances for read only database ? 

I will also try to put this DB in-memory. But does this improvements also applies to in-memory DB ? 

Thank you for your advices.

Guillaume

[Thomas Mueller]

Hi,

Whatever you try to do here, don't use FILE_LOCK=NO. It doesn't do
what you want (see the docs).

What you should do first is to use a profiler to find out where the
bottleneck is. See
http://h2database.com/html/performance.html#built_in_profiler

Regards,
Thomas

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[Guillaume]

Hi, 

Thank you for your answer, I clearly misunderstood something here !

And I will take a look at the profiler.

Regards.

Guillaume

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