I have been working with SQL servers in one form or another for almost two decades now. But I am new to SQL Server Compact Edition. In the past weeks I have been working with SQL Serve CE a lot. The SQL, not a problem, but the engine itself is very new to me.
One of the issues I ran into was a simple SQL statement taking excusive amounts of time; by excessive, I mean over one second. I wrote a little code to time the method. Sometimes it took under one second, other times as long as three seconds. –But it was a simple update statement!
As embarrassing as it is, why it was slow eluded me.
I posted my issue to MSDN and I got a reply from ErikEJ (MS MVP) who runs the blog “Everything SQL Server Compact” . I know little to nothing about SQL Server Compact. This guy is completely obsessed very well versed in CE. If you spend any time in MSDN forums, it seems that this guy single handedly has the answer for every CE question that comes up.
Anyway, he said:
“Opening a connection to a SQL Server Compact database file is a costly operation, keep one connection open per thread (incl. your UI thread) in your app, the one on the UI thread should live for the duration of your app.”
It hit me, all databases have some connection overhead and SQL Server CE is not a database engine running as a service drinking Jolt Cola waiting for someone to talk to him so he can spring into action and show off his quarter-mile sprint capabilities. Imagine if you had to start the SQL Server process every time you needed to make a database connection. Principally, that is what you are doing with SQL Server CE.
For someone who has worked with Enterprise Level SQL Servers a lot, I had to come to the mental image that my Open connection to SQL Server CE is basically starting a service, my own private service, and by closing the connection, I am shutting down my little private service.
After making the changes in my code, I lost any reservations I had with using CE.
At present, my Data Access Layer class has a constructor; in that constructor I open my connection, I also have OpenConnection and CloseConnection methods, I also implemented IDisposable and clean up any connections in Dispose(). I am still finalizing how this assembly will function. – That’s beside the point.
All I’m trying to say is:
“Opening a connection to a SQL Server Compact database file is a costly operation”
