Urgently need to de-fragment entire production DB

Question

I would like to try something but need to check first if it is going to work.
We urgently need to reorganize/defrag our production database server but cannot get sufficient down time. The Oracle version we are using is 8.1.7.4, running on HP-UX 11 unix operating system.
However I had a thought. I currently have a spare machine with sufficient RAM, CPU and disk capacity to restore the Production Database server on to. Then I could simply do a de-frag (ie export/import) of the entire DB on the restored system, leaving the Production DB server operational. Once de-fragged the restored system could be brought up to date by manually applying copies of the archived redo logs off the real Production database server. The final step would involve restoring the de-fragged system back on to the actual Production Database server. Hope this makes sense.
Can anyone confirm if this is going to work?
If this will not work can anyone suggest how I could completely de-frag my production database server, without upgrading the Oracle version or buying any additional software, possibly making use of the spare machine I have?
Many thanks
Khalil

Answer 1

If you need to defrag now, then without some kind of plan to change the way that you organize tablesand indexes you're going to have to defrag in the future.
Avoiding fragmentation is simple -- you assign tables and indexes to tablespaces based on their size, and you ensure that every segment within each tablespace is the same size. You do this by always setting pctincrease to zero, and always setting initial = next.
In your case you can defragment segment by segment by creating new tablespaces based on extent sizes of 64kb, 1Mb, and 16Mb (for example), and over a number of small downtimes you can ...
ALTER TABLE MY_TABLE MOVE TABLESPACE MB16_01 INITIAL 1024kb NEXT 1024kB PCTINCREASE 0;
-- for each index on MY_TABLE ...
ALTER INDEX MY_INDEX_01 REBUILD TABLESPACE KB64_01 INITIAL 64kb NEXT 64KB PCTINCREASE 0;
ALTER INDEX MY_INDEX_02 REBUILD TABLESPACE KB64_01 INITIAL 64kb NEXT 64KB PCTINCREASE 0;Thoughts, anyone?