How to judge a table need export/import?

[Fred Ruffet]

Eric,

IMHO, monitoring table fragmentation is part of DBA's job, as far as disks fragmentation is part of Sysadmin's. Now both have some ways to deal with this problem.

Regarding DBA's job, it is now much better to go into 'alter table xxx move' process than export/import. This will help removing chained rows and too big high water marks (fragmentation itself could be avoided using, for example, local management and uniform extent size).

If your problem is high water mark, you should find a way to have a ratio between high water mark and real data size for which your performance seems to be no more acceptable. Then you can produce a script telling which tables reach this ratio and so need rebuild (move). Running it periodically will help keep better perfs.

Regards,

Fred

[Fred Ruffet]

This doc is also not too bad ;)

Regards,

Fred