Re: Performance issue

Hans S'derlund <hans.soderlund@sundsvall.mail.telia.com> wrote: :We are using Informix 7.2 : : Two questions, I hope anyone know something about it: : : 1) Does select max(colname) generate a full scan if colname is the : primary key? A simple test would have shown you that it does not. It uses any index available for this, not only primary key based index. With an index on the column the result is return immediately. : 2) Does the order of the search criteras in a where clause inflict : the performance? (where a=1 and b='aaa' and c=2) No. The optimiser will find what it thinks is the best way to access the table(s) independent of the order you write the criteria. In this case it works exactly as a relational database should work. You give the criteria. It finds the data in the most efficient way it can. Nils.Myklebust@idg.no NM Data AS, P.O.Box 9090 Gronland, N-0133 Oslo, Norway My opinions are those of my company The Informix FAQ is at http://www.iiug.org