Brian has a interesting post about his discovery of the new EXCEPT set operator in SQL Server 2005.  When I read his post I was at first excited, but then disappointed.  You see, the EXCEPT set operator could potentially save us from updating or inserting a large number of records in the data imports that our system runs.  Unfortunatly, we currently support BOTH Oracle and SQL Server so this new and exciting SQL Server 2005 feature wouldn't help us with many of our clients (since they're primarily on Oracle).  However, after a little bit of Googling I came across the MINUS operator in Oracle, which appears to be the equivalent of the SQL Server 2005 EXCEPT operator.  I'll have to dig into things a little more to know if the EXCEPT and MINUS set operators are equivalent, as well as run some tests to see what kind of impact it could have on our data imports, but it looks promising.

Today at work we had a brief discussion about whether using an IN or an EXISTS is more performant.  There were a couple different opinions, although most thought that EXISTS was faster.  It turns out that like most things in our wonderful software world there is not clear cut answer.  In general the below holds true:

• If the majority of the filtering criteria are in the subquery then the IN variation may be more performant.
• If the majority of the filtering criteria are in the top query then the EXISTS variation may be more performant.

Source: http://www.oracle-base.com/articles/misc/EfficientSQLStatements.php#Exists and this.

I assume the same holds true for SQL Server, although we're less interested in that at the moment.

Recently we've been discussing ways to increase the performance of some performance critical areas of our application.  As such, a number of individuals have been doing research into various options.  Through our investigation we came upon Oracle's Timesten In-Memory database.  I was familiar with many other In-Memory databases, such as Firebird (SQLite?, VistaDB?), but up until yesterday I wasn't aware that Oracle had a product in the in-memory space.  While Oracle doesn't currently offer a .NET native provider for Timesten, TankardSoft does offer a commercial native .NET data provider for Timesten that supports the recently released version 7 of Timesten.