Re: SQL - Optimizer issues

Posted in 1999

John Harman — Wed, 1 Dec 1999 16:03:12 +1100 (EST) — source: Informix-list mailing list archive (1991-1998)

On Tue, 30 Nov 1999, Rajesh wrote: > I have an SQL query in a 4GL program that joins three tables. Informix > version 7.24. The query chooses the correct path for one set of values in > the query. For another set of values, it chooses an entirely different > (wrong) path. The behaviour of the second query is not consistant. All of a > sudden, the second query starts working fine. Consequently the users have > split second response at some times and very long waits at the other. Hard to tell without seeing the query. It may be that the second parts behaviour is being influenced, or not, by the first part, hence the inconsistant execution time. The syntax of sql queries can also influence their performance. John