INCREASING LATCH HIT RATIO

[dbafreak]

Dear friends,

When I execute:

SELECT (1 - (Sum(misses) / Sum(gets))) * 100
INTO v_value
FROM v$latch;
DBMS_Output.Put('Latch Hit Ratio : ' || Format(v_value));


I am getting a very low value (less than 70%). I don't see any parameter in the INIT.ORA file to increase the number of latches.


Kindly advise me how to increase the latch hit ratio. Your help will be appreciated.

[vinit]

db_block_lru_latches is the parameter. (this is for db block buffers only)
t

[ovidius]

As I know, in Oracle 9i you do NOT tune the latches.

[Shestakov]

Originally posted by ovidius
As I know, in Oracle 9i you do NOT tune the latches.

In Oracle 7,8,8i this parameter has name db_block_lru_latches
In Oracle 9i --> _db_block_lru_latches

Default value of this parameter(s) is #CPU/2
Max value for db_block_lru_latches is:
Oracle 7 --> 2*#CPU
Oracle 8,8i --> 6*#CPU
I don't sure about 9i (_db_block_lru_latches) but probably max vallue more then
6*#CPU

--------------------------------------------------
Addition (indirect) method for setup # of lru latches in 9i (8i):

BUFFER_POOL_KEEP = {integer |(BUFFERS:integer, LRU_LATCHES:integer)}
BUFFER_POOL_RECYCLE = {integer | (BUFFERS:integer, LRU_LATCHES:integer)}


[Edited by Shestakov on 04-01-2002 at 11:35 AM]

[dbafreak]

Originally posted by Shestakov

Originally posted by ovidius
As I know, in Oracle 9i you do NOT tune the latches.

In Oracle 7,8,8i this parameter has name db_block_lru_latches
In Oracle 9i --> _db_block_lru_latches

Default value of this parameter(s) is #CPU/2
Max value for db_block_lru_latches is:
Oracle 7 --> 2*#CPU
Oracle 8,8i --> 6*#CPU
I don't sure about 9i (_db_block_lru_latches) but probably max vallue more then
6*#CPU

--------------------------------------------------
Addition (indirect) method for setup # of lru latches in 9i (8i):

BUFFER_POOL_KEEP = {integer |(BUFFERS:integer, LRU_LATCHES:integer)}
BUFFER_POOL_RECYCLE = {integer | (BUFFERS:integer, LRU_LATCHES:integer)}


[Edited by Shestakov on 04-01-2002 at 11:35 AM]

Excellent Shestakov. Many thanks for the information.