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From David Leader <d.lea...@bio.gla.ac.uk>
Subject Re: Accessing embedded database in JAR file
Date Thu, 09 Aug 2007 19:36:49 GMT
Thomas replied to my query:

> David Leader wrote:
>
>> While I mention this, could I perhaps raise the remaining speed  
>> problem. I made a Derby database with one table, two fields and  
>> two tuples (can't get much smaller) and am running it unzipped  
>> from a java app that has the simplest gui with a menu with the two  
>> fields as menu items and a text area for results. After the GUI  
>> has opened the first query takes perhaps five or ten seconds,  
>> whereas the subsequent ones are 'instantaneous'. Anyone know why?
>>
>
> David,
>
> My initial guess is those few seconds on the first query are your  
> initialization cost - that is, starting the derby engine (if  
> embedded), loading the driver and setting up the jdbc connection,  
> and then getting the first statement through.
>
> On a small db, five secs sounds like a lot - but still very possible.
>
> Does it take that long to start if you use ij as well? Does it make  
> a difference wether you run embedded or not?

Using ij it certainly doesn't take as long, but there is a  
perceptable lag before the database connection is made, and the first  
time a query is made it is perceptably slower than the second time -  
perhaps just a second compared with apparently instantaneous. I  
haven't done anything in a non-embedded setup, but I guess you are  
right and it's something one just has to live with. Despite a few  
problems in porting the stuff from MySQL, I must say that overall I'm  
very pleased with the result. My thanks to the Derby team.

(Although my son says I should be using SQLite because Google is  
using that for Gears. Sigh.)

David

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