Is a Union efficient?

Posted in 1999

strangiato@my-deja.com — Tue, 14 Sep 1999 12:59:41 GMT — source: Informix-list mailing list archive (1991-1998)

Online 7.3x Is a UNION more efficient than separate SELECTs? Thanks! Sent via Deja.com http://www.deja.com/ Share what you know. Learn what you don't.

↪ replying to strangiato@my-deja.com

Art S. Kagel — Tue, 14 Sep 1999 18:08:16 -0400 — source: Informix-list mailing list archive (1991-1998)

A UNION CAN be since without the ALL clause it eliminates duplicates between the several selects in the UNION and so MAY return less data at the cost of the neccessary sort. So if the duplicate elimination saves more than the sort/filter costs that yes otherwise no. Art S. Kagel strangiato@my-deja.com wrote: > > Online 7.3x > > Is a UNION more efficient than separate SELECTs? > > Thanks! > > Sent via Deja.com http://www.deja.com/ > Share what you know. Learn what you don't.