Re: How many extents is too many?

Actually, they do hurt performance even if they are contiguous. We had a table that grew continuously (Oracle could never explain why) and never reused blocks. Full table scans went from a few seconds to several minutes, and nothing else was in the tablespace. Oracle doesn't know that extents are contiguous - it basically has to stop the block scan, close the previous extent, open the new extent and initialize all the internal stuff for the new extent before it can continue with the scan. Extensive extents is an indication of poor design or unexpected growth and should be corrected if possible.

Mr. Richardjr F. Sullivan wrote:
>
> I've had hundreds of extents, however they were for the same table in a
>
> tablespace of their own, making the extents contiguous anyway. Extents
>
> seem to bother performance only when they are scattered about in a
>
> tablespace amongst many tables/indexes and either full table scans are
>
> performed or there is already contention for that disk. Subsequent
>
> reorgs should occur on a regular basis anyway for PM purposes......
> Just my $.03 (inflation....!)
 

-- 
---
Allen Kirby			AT&T ITS Production Services
akirby_at_att.com			Alpharetta, GA.