Re: Clustered indexes - again

robert@clark.netkonect.co.uk (Robert Clark) wrote: >OK, >I have now had a few responses to my original Q about clustered >indexes - thanks to all of you. >Dan Madvig (d-madvig@bethel.edu) said: >> If you leave it chustered, then every time the index changes >> the engine has to shuffle the data to match. If the index >> doesn't change much, it couldn't hurt. >Craig (craig.chemistry.chem.utah.edu) said: >> Creating a clustered index on a table does not affect future >> inserts or updates. That is to say, new inserts/updates ignore >> the cluster flag. So, no performance hits. (I think the only >> reason the cluster flag remains set is so you get an error if >> you try to cluster on another index.) >So given these responses I am confused. Does leaving an index >clustered effect future inserts/updates etc? Craig is right, Dan is a little off on this one. A clustered index will remain clustered only if the data is static. If you do inserts/updates after the index has been clustered, then your new table/data will not be in clustered order on that index anymore. That is why future updates have no performance hits in terms of whether a table is clustered or not, the clustered index is ignored. -- Melvin Mariney, Informix DBA e-mail: melvin.mariney2@bridge.bellsouth.com