Index optimization output

Question

I have a database running on 11.1.0.7 on a Linux 64 bit machine.I want to know the effect of doing an index optimization through these 2 queries.
Will it help in improving the performance if the fragmentation is more than 20%? Any help would be really appreaciated!
begin
ctx_output.start_log('opt_rebuild_TEXT2');
ctx_output.add_event(ctx_output.event_opt_print_token);
ctx_ddl.optimize_index(idx_name=>'TEXT2',optlevel=>'REBUILD');
ctx_output.end_log;
end;
begin
ctx_output.start_log('opt_rebuild_TEXT1');
ctx_output.add_event(ctx_output.event_opt_print_token);
ctx_ddl.optimize_index(idx_name=>'TEXT1',optlevel=>'REBUILD');
ctx_output.end_log;
end;
Thanks in advance.

Answer 1

Hi,
as the manual states for this procedure: "Optimizing an index removes old data and minimizes index fragmentation, which can improve query response time". So yes it can improve, but if the fragmention is on words you never use, then it won't help, if the fragmentation is on words you frequently use, then it will certainly help. It compacts the index, so it can quicker find the corresponding rows.
You can always test yourself of course. Test a query, wait for a 20% fragmentation, test the query again, optimize and test again. If the last query time is better than the 2nd one, you know it helps.
Herald ten Dam
http://htendam.wordpress.com