Oracle-L: RE: Question about buffer cache

From: Darrell Landrum <DLANDRUM_at_zalecorp.com>
Date: Thu, 20 Feb 2003 08:54:09 -0800
Message-ID: <F001.00553083.20030220085409@fatcity.com>

Hi John,

If I'm understanding what I'm reading from the 9i Concepts Guide, I think that non-default block size objects can only go into the cache with the same block size (meaning it can't go into keep buffer). I'm making this assumption because we can't create a tablespace of 16k blocksize until db_16k_cache exists. However, I'm working on testing this today and will reply with results.

Darrell

>>> JBaylis_at_mail.canfor.ca 02/19/03 01:50PM >>> I have indexes in a 16k page size tablespace. I have the following init.ora parameters:

db_block_size=4096
db_cache_size=600M
db_keep_cache_size=200M
db_16k_cache_size=200M

If I alter an index to put it in the keep pool, how does Oracle hande the discrepancy between the 4k default keep buffer and the 16k index block size?

Am I better off keeping the index in the 16k cache or in the db_keep_cache pool?

Since statspack shows:

Event                               Waits   Timeouts   Time (s)   (ms)

/txn

---------------------------- ------------ ---------- ---------- ------
--------
db file sequential read         2,725,553          0     40,710     15

355.2

I assume my indexes should be cached more to reduce the waits. Is that correct?

Any advice would be appreciated.

Thanks

John Baylis
Database Administrator
Canadian Forest Products Ltd.
Vancouver B.C. Canada

> (604) 697-6476 (Office)
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Author: Darrell Landrum
  INET: DLANDRUM_at_zalecorp.com

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Received on Thu Feb 20 2003 - 10:54:09 CST