At 11:02 AM 5/06/2003 +0000, you wrote:

>Alexander,
>Although I index this column, the performance is still the same. or
>even slower.

Why is this column indexed, if it's going to take an update that sets its
value in every row to '1'? It sounds like the classic "index of low
selectivity" problem. Your update is crawling up and down very long index
chains.

Drop the index and try the update again.

>So, I execute "gbak -b -g" to clear the garbage. I don't see any
>improvement too.

This won't clear all the garbage if you have a big gap between the oldest
transaction and the current. It will only clear garbage that is older than
the oldest transaction.

heLen