Statistics

Posted in 2003

Topics: Versions, Editions & End-of-Life

Demeis, Tony — Tue, 27 May 2003 18:54:40 — source: IIUG Forums & Mailing Lists

Hi, Assume there is a table containing indexes built with a combination of single & composite keys. Is it of any use to run the low for statistics or is it sufficient to run high on all columns, that is, just run high individually on a, b, c and d? index1 = (a,b) index2 = (c,d) index3 = (b) index4 = (d) (IDS 7.31) Thank you, Tony

↪ replying to Demeis, Tony

KEVIN STRUCKHOFF — Thu, 29 May 2003 22:13:58 — source: IIUG Forums & Mailing Lists

Tony, It is my understanding from the Performance & Tuning Class that you want to perform update stats high on the first column of a composite index and low on the remaining columns. HTH Kevin Struckhoff Data Warehouse Consultant Yamaha Motors kevin_struckhoff@yamaha-motor.com

↪ replying to KEVIN STRUCKHOFF

ART KAGEL, BLOOMBERG/ 65E 55TH — Fri, 30 May 2003 13:32:18 — source: IIUG Forums & Mailing Lists

HIGH on the initial column of each index and on the first different column if two or more indexes include the same initial set of columns, then LOW on the ENTIRE KEY for each index. From the Performance Guide: Step 4. For each multicolumn index, execute UPDATE STATISTICS LOW for all of its columns. For single-column indexes in the preceding step (step 3) UPDATE STATISTICS LOW is implicitely executed when you execute UPDATE STATISTICS HIGH. Art S. Kagel ----- Original Message ----- From: Kevin Struc.... <kevinstruckhoff@yahoo.com> At: 5/29 18:31 > Tony, > > It is my understanding from the Performance & Tuning Class that you want to > perform update stats high on the first column of a composite index and low on > the remaining columns. > > HTH > > Kevin Struckhoff > Data Warehouse Consultant > Yamaha Motors > kevin_struckhoff@yamaha-motor.com