On Oct 9, 5:56 am, MTNorman <mtnor..._at_duke-energy.com> wrote:
...
> So if the index avg row length is a fraction of the table avg row
> length and the index storage is still a multiple of the table storage
> (30 bytes on the index, 200 bytes on the table, 10g for the table, 20g
> for the index) - you may want consider reindexing. The ratio does not
> necessarily mean rebuilding is needed - it's just a tool/method for
> identifying indexes to examine. A better method may be segment
> activity - fragmented indexes that are causing performance problems in
> OLTP also tend to be among the most active segments.
I quite like that advice. It's not simplistic ("If index is lots
bigger than table, then it needs further investigation") and it asks
for cross-checking with other metrics (in this case, segment activity,
but I wouldn't rule out throwing in the del_lf_rows/lf_rows measure,
too). Much, much better than "if some ratio=20%, rebuild"!!
Received on Mon Oct 08 2007 - 22:15:28 CDT
