Re: Overflow Distributions in Online 7.20

Mark D. Stock wrote: > > Art S. Kagel wrote: > > > > mc wrote: > > > > > > I am having a performance problem in Online 7.20. When I look at > > the > > > distributions on the table using the "dbschema -hd" command , I > > notice that [SNIP] > That is true, but overflow bins indicate highly duplicate key values. If > most of your keys are highly duplicate, then this could impact on > performance. A very long and narrow B-Tree structure will incur a lot > more IO. If you have highly duplicate key values, consider adding > additional columns to them to increase their uniqueness. Not neccessarily so, Mark. The distributions are recorded on individual columns, high duplication on a single column does not imply high duplication within compound indexes only within a singleton index on the column in question. You are right that it MAY indicate a high duplication factor and this should be looked at but it does not of neccessity imply this. Art S. Kagel