Re: Are multiple extents still a problem with LMT?

"Andy Kent" wrote ...
[...]
> 2. Large queries and especially full scans are compromised because the
> data blocks do not occupy contiguous space so seek time is increased.
> However where datafiles use filesystem space the filesystem is likely
> to add its own fragmentation overhead so making everything [logically]
> contiguous within a datafile may be a lost cause.
[...]

[quote]
Oracle supports an unlimited number of extents in a segment.

• The performance for DML operations is largely independent of the number of extents in the segment. ***

However, certain DDL operations such as dropping and truncating of segments are
sensitive to the number of extents. Performance measures for these operations have shown that a few thousand extents can be supported by Oracle without a significant impact on performance. A reasonable maximum has been determined to be 4096. [/quote]

Reference: How To Stop Defragmenting and Start Living: The Definitive Word on Fragmentation White Paper

MetaLink Note:236895.1

Regards
Dimitre Received on Thu Apr 05 2007 - 06:56:38 CDT