Re: database engine

> What exactly does the background process "sqlexec" do? SQLEXEC is the heart of the database engine. In reality, it's one of the really NEAT parts about how Informix works. Rather than having all of the SQL processing, etc inside of the 4GL/ESQL, Informix has created a backend process to handle all of the actual data processing. This has billions and billions of advantages, but I'll only point out a few :-) o Engine Independance By having the engine a seperate process, all the program needs to know is how to open up a pathway between itself and the engine, rather than the mechanics of being the engine itself. This allows you to run the same front end code (Your applications, ISQL, WingZ) on any engine, SE, OnLine, I-NET, or even possbily someone elses engine entirely. You do this by communicating to the engine your requests using some protocol. In theory, your code never changes regardless which engine you're running on. o Security With Informix, your process does not need any special permissions to access the data. The engine does it all for you, so you can have a secure database with an insecure front end. The engine enforces the security itself. If all of this was in your code, then someone somewhere could hack your code to possbily usurp the security. o Performance Particularly with networks, the engine crunches all of the data itself without your program touching any of it until the your request is met. No doubt you've probably discovered that it's faster to do some thing like: SELECT * from table where unkeyed_field="N" Than to do something like: SELECT * form table FOREACH record if unkeyed_field="N" then bla bla bla end if END FOREACH The engine only sends you what you request, doing most of the filtering itself. The 4GL is nowhere near as effeicient doing loops and such as the engine is. And with networks, your bandwidth isn't chewed up with a bunch of generally useless data. (Speaking of bandwidth...) Anyway, those are some of the key points to why it's a seperate process. I don't know if Informix documents how you can call their engine with a custom program, I gather that is what ESQL/C is for. I guess in summary, it's faster to dial 411 than it is to look it up. Will (uunet!la4gen!villy)