Learning by doing

Google has donated Hibernate Shards - a Java 5 add-on to Hibernate that allows application driven data partitioning with your custom or their pre-build configurations. One thing that caught my eye was that when they covered partitioned Native ID generation (aka Identity), they mentioned having Database A use a range 0-200000, Database B use range 200001 - 400000, etc. I know that MySQL cluster suggests using something like this: Database A: Starting ID 1, Increment ID by 3 (number of databases) Database B: Starting ID 2, Increment ID by 3 Database C: Starting ID 3, Increment ID by 3 This allows a hands-off approach, and easily lets you divide ID by 3 and use the remainder to map to a "Shard". Of course, if your data changes significantly, you may have to dump and reload to add another database. One way to avoid a dump and reload is to pick an increment that is larger than your actual database count, and just drop an extra database in an the available Starting ID. This ...

As I have said before, I am developing with Visual Studio 2005 on .Net 2.0. This summer, I will be creating an application with integrated html help. Of course, my first inclination is to refresh my knowledge of help systems by acquiring Microsoft's HTML Help SDK . The HTML Help Workshop looks like it will do light project management, and it even has an image cropping and screen capture program called "Flash". I did not see any full downloadable examples in the MSDN Help SDK area, but they had a link to the Help Wiki . If you browse through the wiki, you will find some good (but dated) help info about C# . DotNetJunkies has a nice step-by-step c# example for integrating help after you have a compiled help file. I am thankful that my application uses .Net 2.0, as .Net 1.x did not have much support for help systems. The .Net 2.0 HelpProvider seems like it will be very useful (here is a tutorial . HTML Help Tidbit: Your help system can be thought of as a self-cont...

I have submitted a patch to add MultiQuery support to ActiveRecord. The link is at http://support.castleproject.org/browse/AR-139 . I added ActiveRecordMultiQuery.cs and updated ActiveRecordBaseQuery.cs to allow subclasses to be aggregated (added) to the MultiQuery. I did this to speed up initialization of a form (I know ... premature optimization is the root of all evil). If you like this patch, log in and vote for it! Update: The patch has been applied. In the mean time, let me caution you that ActiveRecordCriteriaQuery from the svn repository (which I also wrote and contributed) and any other "query" that uses criteria will not correctly participate in a multi-query. But if we give the NHibernate team some time, I'm sure this will be resolved. Regarding the implementation, the only thing that I really wondered about was the "root type". This basically selects the session to be created. So all queries in the multi-query need to be registered with the ...

Update: I have contributed patch AR-156 that allows full integration of Insert, Update and Delete to ActiveRecord models . If you've been reading my blog lately, you know that I have been seriously testing the Castle ActiveRecord framework out. I really love it, but I have an existing Microsoft SQL Server database with many stored procedures in it. I have tested the ActiveRecord model out, and I am sure that I will learn enough to be able to use it for standard CRUD (create, read, update, delete aka. insert, select, update, delete) functionality. BUT ... If I really want to integrate with my existing billing procedures, etc, I will have to be able to call stored procedures. I have taken two approaches ... write the ARHelper.ExecuteNonQuery(targetType, dmlString) method that gets a connection for the supplied type, executes dmlString, and closes it. write the ARHelper.RegisterCustomMapping(targetType, xmlString) method that allows me to add mappings that refer to my auto-gener...

My current development environment is Visual Studio Express C# Edition (read that as free ), Castle ActiveRecord's latest svn trunk(usually within a few days), and NHibernate svn trunk. As of NHibernate version 1.2.0, there is a very cool new class out there ... DetachedCriteria. This class lets you set all of your Castle relational attributes like BelongsTo, HasMany, etc. as lazy fetch, and over-ride this for searches, reports, or anytime you know ahead of time that you will be touching the related classes by calling detachedCriteria.SetFetchMode(..., FetchEnum.Eager). As a good netizen, I have tried to contribute to NHibernate and Castle ActiveRecord even if only in the smallest of ways . Oh yeah, I tried mapping to a SQL VIEW, and it worked GREAT! I received a comment after my last post, indicating that there is a better way, and I am sure of it, but the view guaranteed that I only have one database request for my dataset. NHibernate was wanting to re-fetch my missing as...