2.77 DB_CACHE_SIZE

DB_CACHE_SIZE specifies the size of the DEFAULT buffer pool for buffers with the primary block size (the block size defined by the DB_BLOCK_SIZE initialization parameter).

Note:

Oracle recommends against setting this parameter in a PDB. The only shared memory sizing parameter that should be set in a PDB is SGA_TARGET, which specifies the maximum SGA that the PDB can use at any time.

Property	Description
Parameter type	Big integer
Syntax	DB_CACHE_SIZE = integer [K | M | G]
Default value	If SGA_TARGET is set: If the parameter is not specified, then the default is 0 (internally determined by the Oracle Database). If the parameter is specified, then the user-specified value indicates a minimum value for the memory pool. If SGA_TARGET is not set, then the default is either 48 MB or 4 MB * number of CPUs, whichever is greater
Modifiable	ALTER SYSTEM
Modifiable in a PDB	Yes
Basic	No

The value must be at least 4M * number of cpus (smaller values are automatically rounded up to this value). A user-specified value larger than this is rounded up to the nearest granule size. A value of zero is invalid because it is needed for the DEFAULT memory pool of the primary block size, which is the block size for the SYSTEM tablespace.

See Also:

• "SGA_TARGET"

• Oracle Database Performance Tuning Guide and Oracle Database Administrator’s Guide for more information on setting this parameter

• Oracle Multitenant Administrator's Guide for more information about the initialization parameters that control the memory usage of PDBs