BUFFER_POOL_KEEP

Reference Note for Init.Ora Parameter “BUFFER_POOL_KEEP”.
The information here contains a parameter description from the Oracle9i documentation along with any additional support comments related to this parameter. If the parameter usage is different in Oracle9i to in earlier releases then the details of the earlier usage appear in the “Support / Historical Notes” section below the main description.
Oracle9i Information
Note: Default values and ranges may differ from those shown here due to variations between releases..
Parameter type String

Syntax BUFFER_POOL_KEEP = {integer |

(BUFFERS:integer, LRU_LATCHES:integer)}

where integer is the number of buffers and, optionally, the number of LRU latches.

Default value There is no default value.

Parameter class Static

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Note:
This parameter is deprecated in favor of the . Oracle recommends that you use DB_KEEP_CACHE_SIZE instead. Also, BUFFER_POOL_KEEP cannot be combined with the new dynamic DB_KEEP_CACHE_SIZE parameter; combining these parameters in the same parameter file will produce an error. BUFFER_POOL_KEEP is retained for backward compatibility only.

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BUFFER_POOL_KEEP lets you save objects in the buffer cache by setting aside a portion of the total number of buffers (the value of the DB_BLOCK_BUFFERS parameter) as a KEEP buffer pool. You can also allocate to the KEEP buffer pool a specified portion of the total number of LRU latches.

The string value can take one of two forms. You can simply specify a buffer count:

BUFFER_POOL_KEEP = 5

Or, you can specify a combination of buffers and LRU latches. Specifying LRU latches is optional:

BUFFER_POOL_KEEP = (BUFFERS:400, LRU_LATCHES:3)

This parameter is most useful in combination with the BUFFER_POOL_RECYCLE parameter.

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Support and Historical Notes for “BUFFER_POOL_KEEP”
Related:

This parameter was introduced in Oracle 8.0.
In Oracle9i please use .

Historical Notes:
As of Oracle8 the database buffer cache can be divided into different pools.
Because objects are accessed in different ways and with different
frequency their cache behavior may be quite different. Multiple buffer
pools enable you to address these differences.

The “keep” buffer pool can be used to maintain objects in the buffer
cache for as long as possible.

The “recycle” buffer pool can be used to prevent an object from taking up
unnecessary space in the cache.

A default cache is always maintained for objects which have not been
assigned to one of the buffer pools.

You can create multiple buffer pools by setting the initialization
parameters BUFFER_POOL_KEEP and BUFFER_POOL_RECYCLE. The size of each
buffer pool is subtracted from the total number of buffers defined for the
entire buffer cache.

Set these parameters as (“buffers:nbuf”,”lru_latches:Nlat”).
NOTE: Some documentation states to use ‘nbuf,nlat’ but this may not work
correctly – use the full string (“buffers:nbuf”,”lru_latches:Nlat”)

The latches are subtracted from the total number allocated to the instance,
just like the buffers. Each buffer cache must have at least 50 buffers per
latch.

For example, in the init.ora you could set:

DB_BLOCK_BUFFERS = 1000
DB_BLOCK_LRU_LATCHES = 6
BUFFER_POOL_KEEP = (“buffers:100″,”lru_latches:2”)
BUFFER_POOL_RECYCLE = (“buffers:50″,”lru_latches:1”)

You can ASSIGN which buffer cache a table uses using the BUFFER_POOL
KEEP | RECYCLE | DEFAULT option of the STORAGE clause.

Articles:
Overview of Init.Ora Parameter Reference notes Note 68462.1
.

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Sobre Alexandre Pires

ORACLE OCS Goldengate Specialist, OCE RAC 10g R2, OCP 12C, 11g, 10g , 9i e 8i - Mais de 25 anos de experiência na área de TI. Participei de projetos na G&P alocado na TOK STOK, EDINFOR alocado na TV CIDADE "NET", 3CON Alocado no PÃO DE AÇUCAR, DISCOVER alocado na VIVO, BANCO IBI e TIVIT, SPC BRASIL, UOLDIVEO alocado no CARREFOUR e atualmente na ORACLE ACS atendendo os seguintes projetos: VIVO, CLARO, TIM, CIELO, CAIXA SEGUROS, MAPFRE, PORTO SEGURO, SULAMERICA, BRADESCO SEGUROS, BANCO BRADESCO, BASA, SANTANDER, CNJ, TSE, ELETROPAULO, EDP, SKY, NATURA, ODEBRESHT, NISSEI, SICREDI, CELEPAR, TAM, TIVIT, IBM, SMILES, CELEPAR, SERPRO,OKI,BANCO PAN, etc
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