Re: OTN Tip of the week

"Chris Boyle" <cboyle_at_hargray.com> wrote in message news:VP%kb.31047$N94.16173_at_lakeread02...
> OK, I admit it. I do not understand the problem. Would someone please
> explain why this deserves derision?

The code attempts to build a list of indexes to be rebuilt based on 2 criteria

1. How old the index is.
2. How big the index is

so that you rebuilt your oldest indexes first, but allow for the fact that you may not have enough time in the maintenance window to rebuild every index.

The underlying assumption is that rebuilding your indexes is a Good Thing. In general it is just a waste of time and effort. Even the advice from Oracle suggests that you should only rebuild when you have a depth of 4 or greater and more than 20% of the index entries are deleted entries. Note 232819.1 on metalink.

So, don't rebuild your indexes unless you really need to and decide when you need to based on sensible criteria not time since rebuild. I'm pretty sure that Howard and Richard have some suggestions as to whether the criteria suggested by Oracle above are sensible or not.

-- 
Niall Litchfield
Oracle DBA
Audit Commission UK