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From Ron Chan <rc...@i-tao.com>
Subject Re: Does dao have to be tied to a single database?
Date Fri, 03 Nov 2006 18:54:40 GMT

we have exactly the same need and has created code to hold a hashmap of
connections, which seems to be working.  However, what will happening if we
were to introducing caching, will the different objects from different
databases be mixed together?

Jeff Butler-2 wrote:
> What you're doing with the HashMap is very similar to what the DAO manager
> does with multiple contexts.  So you're right - that won't buy you
> anything.  What's causing the overhead is that you're loading the SqlMap
> configuration into memory 100 times - once for each database.  Multiple
> contexts in a DAO configuration would do the same thing.
> If the database schemas are the same and only the connection is different,
> then you could use the setUserConnection method to supply the connection
> at
> run time.  So then you would only need to load the SqlMap configuration
> into
> memory one time, keep a HashMap of connections, then set the connection
> before calling SqlMap functions.
> Jeff Butler
> On 10/23/06, Barnett, Brian W. <brian.barnett@pearson.com> wrote:
>>  We have an app that currently services over 100 different customers,
>> each
>> having their own SQL Server or Oracle database. We host the web app and
>> the
>> databases on our servers.
>> The solution we came up with a few years ago was to have a HashMap of
>> DaoManager objects, one DaoManager object for each database, keyed by
>> customer name in the HashMap. With the 100+ customers we have now, these
>> daoManager objects consume around 400Meg of memory total. Obviously, as
>> our
>> customer base grows, this will eventually kill us.
>> So the question we have is, "Does a dao, or DaoManager, have to be tied
>> to
>> a single database?" I suspect this may not be the correct question, but
>> it
>> is the only one I can come up with right now. Wondering if we can have
>> one
>> DaoManager and when we request a dao, also tell the manager which
>> database
>> we want the dao to operate on.
>> Is there a better way to handle this situation? I've read that you can
>> use
>> multiple contexts in the dao.xml file, but I'm not sure if this would
>> solve the memory problem we are having.
>> We are currently running iBatis 2.1.0.
>> TIA,
>> Brian Barnett
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