Buffer cache hit very low...!!!

From: Chirag DBA <chiragdba_at_gmail.com>
Date: Tue, 13 Sep 2005 14:53:36 -0400
Message-ID: <1a36296005091311532cd0117a@mail.gmail.com>

Hi Team,
My OEM shows buffer cache hit ratio as 28% and library cache as 99%. Another query shows different results for buffer cache.

SQL> SELECT NAME,100-PHYSICAL_READS/(DB_BLOCK_GETS + CONSISTENT_GETS) FROM V$BUFFER_POOL_STATISTICS; NAME 100-PHYSICAL_READS/(DB_BLOCK_GETS+CONSISTENT_GETS)
-------------------- --------------------------------------------------
DEFAULT 99.9072457 SQL> show sga

Total System Global Area 252273320 bytes Fixed Size 434856 bytes
Variable Size 150994944 bytes
Database Buffers 100663296 bytes
Redo Buffers 180224 bytes

And my db_block_buffers show value as 0.

but it should be the value of database buffers / db_block_size .

SQL> show parameter db_block

NAME TYPE VALUE
------------------------------------ ----------- ----------------------

db_block_buffers integer 0
db_block_checking boolean FALSE
db_block_checksum boolean TRUE
db_block_size integer 8192

Is really my buffer cache hits very low?

Regards - Chirag

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http://www.freelists.org/webpage/oracle-l Received on Tue Sep 13 2005 - 13:58:27 CDT