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From "Jeff Butler" <jeffgbut...@gmail.com>
Subject Re: Does dao have to be tied to a single database?
Date Tue, 24 Oct 2006 15:09:45 GMT
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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