which "where condition" I should use?

Posted in 1996

Madeline Wu — 21 Nov 1996 05:09:51 GMT — source: Informix-list mailing list archive (1991-1998)

Our engineer is ONLINE 5.0. When I set explain on, the result is: 1) update tables set field="value" where uniqe_index_value estimated cost: 1 2) update tables set field="value" where rowid=num estimated cost: 13288 Is it mean "where condition" use uniqe index value is better than use rowid ?? Or just INFORMIX get wrong estimated cost? (I remember rowid is a uniqe index too.)