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From Bryan Pendleton <bpendleton.de...@gmail.com>
Subject Re: Does derby database need periodic maintenance/cleanup activity ?
Date Thu, 20 May 2010 14:08:44 GMT
 > It is observed that, if derby database runs continuously for say around 5 hrs.
 > It becomes really slow for further queries even with fresh DB calls.

Unless you are adding data dramatically fast, I don't think you should need
to do cleanup or maintenance on the database itself very frequently. I've
seen Derby systems (well-tuned ones) run for weeks or months of constant
use without slowing down noticeably.

If it slows down noticeably in just 5 hours, that sounds like a memory leak
of some sort. Perhaps you are not closing your connection or statement or
result set objects in a timely fashion, and the garbage collector is having
to work very hard to find objects that can be reclaimed?

The next time the system is running quite slowly, try gathering some
information from it. For example, you can use a tool like VisualVM to see
some overall information such as how much CPU you're using, how much memory
you're using, how much of the memory is free, how many threads you have, etc.

Also, try taking a memory dump of the running system, then analyze it with
a tool like the Eclipse Memory Analysis Tool and get a histogram of the
memory contents.

If you can give the list some more information, such as what is the breakdown
of the most-used object types in memory, and what the overall system looks
like and is doing during the slowdown, I'm sure people can offer more specific
suggestions.

thanks,

bryan


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