Re: Update Statistics Plan for IDS 7.31

Posted in 1999

Chuck Renaud — Tue, 19 Oct 1999 17:04:32 -0500 — source: Informix-list mailing list archive (1991-1998)

For composite indexes, USH should be run for the first column and first distinct columns in each index. So it should be for columns a, c and d. > From: "Carlson@WHSmith" <carlson1@bellsouth.net> > > > >Or should that be columns a, c, and d??? > > ART?!?!? :-) > > >Obnoxio The Clown wrote: > > > > > > From: "Adam Bradley" <Adam.Bradley@ahmg.com.au> > > > > > > > >2. Run the "UPDATE STATISTICS HIGH" command with "DISTRIBUTIONS ONLY" > > > > > >for > > > >all columns that head an index.This accuracy will give the optimizer > >the > > > >best data about an index's selectivity. > > > > > > AFAIK: > > > If you have two indexes > > > > > > index1 on table (a, b, c) > > > index2 on table (a, b, d) > > > > > > You should use USHDO on columns a and b.