Question

I am building an application and I want to batch multiple queries into a single round-trip to the database. For example, lets say a single page needs to display a list of users, a list of groups and a list of permissions.

So I have stored procs (or just simple sql commands like “select * from Users”), and I want to execute three of them. However, to populate this one page I have to make 3 round trips.

Now I could write a single stored proc (“getUsersTeamsAndPermissions”) or execute a single SQL command “select * from Users;exec getTeams;select * from Permissions”.

But I was wondering if there was a better way to specify to do 3 operations in a single round trip. Benefits include being easier to unit test, and allowing the database engine to parrallelize the queries.

I’m using C# 3.5 and SQL Server 2008.

Answer 1

The single multi-part command and the stored procedure options that you mention are the two options. You can’t do them in such a way that they are “parallelized” on the db. However, both of those options does result in a single round trip, so you’re good there. There’s no way to send them more efficiently. In sql server 2005 onwards, a multi-part command that is fully parameterized is very efficient.

Edit: adding information on why cram into a single call.

Although you don’t want to care too much about reducing calls, there can be legitimate reasons for this.

• I once was limited to a crummy ODBC driver against a mainframe, and there was a 1.2 second overhead on each call! I’m serious. There were times when I crammed a little extra into my db calls. Not pretty.
• You also might find yourself in a situation where you have to configure your sql queries somewhere, and you can’t just make 3 calls: it has to be one. It shouldn’t be that way, bad design, but it is. You do what you gotta do!
• Sometimes of course it can be very good to encapsulate multiple steps in a stored procedure. Usually not for saving round trips though, but for tighter transactions, getting ID for new records, constraining for permissions, providing encapsulation, blah blah blah.