Re: create index nologging does not improve performance

Mike F doodled thusly, after I reduced the x-posting:

>create unique index ........ logging
>Elapsed: 00:03:230.90
>
>create unique index ........ nologging
>Elapsed: 00:03:218.41

Hmmm, you just saved the writing in the redo log of the CREATE INDEX statement and possibly a few dictionary updates/inserts. Exactly what were you expecting? The redo logs don't store the ENTIRE index! Just the create statement and little else.

>
>create unique index .........nologging parallel (degree 2);
>Elapsed: 00:04:282.39
>

This is what you should be worried about. Was the original no parallel? IOW, what is the setting of parallel in the table? How many CPU's do you have? Are you getting lots of wait on I/O when the read phase of the create index executes? This should take less time, not more. It is the real problem that you have to address.

Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam Received on Sat Apr 13 2002 - 20:42:18 CDT