Informix query optimizer info please

I am looking for detailed information on how the Informix query optimizer operates (i.e. makes its decisions, what it looks for, good tips on how to formulate tricky queries, etc.) I have a reasonable amount of experience in the land of Sybase, but I'm new to Informix. After I worked with Sybase for awhile, I learned about the guts of the optimizer and it helped me tremendously. Wish I had known the details earlier. So, since I'm new to Informix, I'd like to start by learning about its optimizer. Are there any articles, books, ftp sites, etc. that would give me some insights? Any and all tips would be greatly appreciated! Thanks! (BTW, I'm using ver 5.0 on a unix server and PC/DOS version 4.1 to access the server) -bill -- ============ Bill Ryan ryan@marcam.com