RE: extent allocation

From: Jacques Kilchoer <Jacques.Kilchoer_at_quest.com>
Date: Wed, 23 Jun 2004 10:28:38 -0700
Message-ID: <B5C5F99D765BB744B54FFDF35F60262109F8791A@irvmbxw02>

Thank you for the correction, my answer was sadly incomplete. I was only thinking of number of extents per segment. Obviously you want to avoid wasted space when choosing the extent size (e.g. don't choose uniform 1 MB for very small tables.) A multiple of db_file_multiblock_read_count * block_size is also good in general (at least that's what I've read in the past and you confirm that.)

-----Original Message-----

Paul Drake

I did not catch the OS of the OP.

not even a good guess of a multiple of the db file multiblock read count times the database block size?

on win32 OSes, I've seen no discounting of the dbfmbrc down from either 16 or 32 during full table scans against RAID volumes with a stripe size of 256 KB (8KB block size).

so why not start with an extent size of 128 KB for small and go from there?
If you have 10,000 tables and indexes that only have 5 blocks allocated, you might want to go smaller.

In that case, you might want to use a 2 KB block size and put them in their own tablespace and buffer pool

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Received on Wed Jun 23 2004 - 12:25:43 CDT