I am running the following (Oracle suggested - 8i) query to get the biffer hit ratio.
This is our production Apps database. The numbers for logical and physical reads seem
VERY high (especially phys_reads, which obviously causes our hit ratio to drop to 0).
What could have caused this?
SQL> list
1 select A.value + B.value "logical_reads",
2 C.value "phys_reads",
3 D.value "phy_writes",
4 (A.value+B.value)-C.value "log_minus_phys",
5 round(100 * ((A.value+B.value)-C.value) / (A.value+B.value))
6 "Buffer Hit Ratio"
7 from V$SYSSTAT A, V$SYSSTAT B, V$SYSSTAT C, V$SYSSTAT D
8 where A.statistic# = 38
9 AND B.statistic# = 39
10 AND C.statistic# = 40
11* AND D.statistic# = 44
SQL> /
logical_reads phys_reads phy_writes
log_minus_phys Buffer Hit Ratio
---------------------------- ---------------------------- ----------------
---------------- ----------------
18,446,744,070,414,253,130 18,446,744,069,433,707,559 2,043,488
980,545,571 0
Here are some other stats;
DTSTAMP PHYSICAL_READS DB_BLOCK_GETS
CONSISTENT_GETS PHYSICAL_WRITES
-------------------- ---------------------------- ----------------
---------------------------- ---------------
PHYSICAL_READS_DIRECT PHYSICAL_WRITES_DIRECT SESSION_LOGICAL_READS
---------------------------- ---------------------- ---------------------
08-APR-2002 10:35:16 18,446,744,069,434,437,169 171,781,916
18,446,744,070,280,471,598 2,103,859
18,446,744,047,946,114,866 966,679 1,032,014,671
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Author: Glenn Travis
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Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
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