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From Thomas Nielsen <Thomas.Niel...@Sun.COM>
Subject Re: Help Urgent:Apache derby network server
Date Sat, 22 Dec 2007 05:47:27 GMT

That statement does not mean Derby has a limit of 25 concurrent clients. 
Like Brian said in his reply, Derby can handle thousands of connections, 
and they can all work at the same time. The statement is most likely the 
result of a simple "sanity test" the author of the article did, or 
refers to, with (pick a number, any number) 25 concurrent clients to see 
if the different databases handle concurrency at all, and if so how well 
they do.

Adding more clients normally increase total throughput, to a certain 
degree, and with performance depending on the utilization of the system 
running the database, also like Brian suggested. There is a tradeoff - 
by adding more client you may experience longer execution time in each 
connection. Remember all your concurrnet clients are competing for a 
piece of the available resources on the database host to execute their 
query. Unless you are executng really complex queries, dealing with huge 
amounts of data, or a lot(!) of connections, you would most likely still 
be talking milliseconds timeframe. It all depends on what, and how much, 
you are trying to do. The clients normally use a lot more time on the 
client side than on the database side, especially so if there is user 
interaction on the client side.

Hope this helps,


musky wrote:
> thanks for your quick reply:
> i read a comparison of mysql and apache derby and i found this line
> interesting:
> "it easily handles processing requests of 25 concurrent connections".
> source:"http://www.devx.com/ibm/Article/28526"
> what does this mean?
> does it mean that only 25 remote hosts can access the database simuaneously?
> please help.
> Bryan Pendleton wrote:
>>> i want to know how many hosts can access(both insertion and retrieval)the
>>> derby database via the derby network server. 
>> You mean, at the same time? Thousands.
>> The limits aren't in Derby itself, but involve things like:
>>   - whether your operating system can scale well
>>   - how much hardware you can afford
>>   - how carefully you write your application.
>> If your clients aren't simultaneously accessing Derby, then
>> the limits are even higher.
>> thanks,
>> bryan

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