SHARED_POOL_SIZE specifies (in bytes) the size of the shared pool.

Property Description

Parameter type

Big integer


SHARED_POOL_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 (32-bit platforms): 64 MB, rounded up to the nearest granule size.

If SGA_TARGET is not set (64-bit platforms): 128 MB, rounded up to the nearest granule size.

For considerations when dealing with database instances using Oracle ASM, see "SHARED_POOL_SIZE and Automatic Storage Management".



Modifiable in a PDB


Range of values

Minimum: the granule size

Maximum: operating system-dependent



The shared pool contains shared cursors, stored procedures, control structures, and other structures. If SGA_TARGET is not set, then Oracle also allocates parallel execution message buffers from the shared pool. Larger values improve performance in multiuser systems. Smaller values use less memory.

You can monitor utilization of the shared pool by querying the view V$SGASTAT.


This parameter is optional for pluggable databases (PDBs). When this parameter is set for a PDB, it guarantees the shared pool size for the PDB. When this parameter is not set at the PDB level, the PDB has no limit for the amount of shared pool it can use, other than the CDB's shared pool size.

To be able to use Resource Manager in a CDB to control the amount of memory each PDB can use:

  • The NONCDB_COMPATIBLE initialization parameter must be set to FALSE at the CDB level (in the root of the CDB).

  • The MEMORY_TARGET initialization parameter must not be set at the CDB level.

  • If the SGA_TARGET initialization parameter is not set, but the SHARED_POOL_SIZE initialization parameter is set at the CDB level, then the following requirements must be met:

    • The value of SHARED_POOL_SIZE set in a PDB must be less than or equal to 50% of the SHARED_POOL_SIZE value at the CDB level.

    • The sum of the SHARED_POOL_SIZE values across all the PDBs in the CDB must be less than or equal to 50% of the SHARED_POOL_SIZE value at the CDB level.

    When you set SHARED_POOL_SIZE in a PDB to a value that does not meet these requirements, you receive an error. If these requirements are violated after the PDB’s parameter is set (for example, if the SHARED_POOL_SIZE value is changed at the CDB level, Oracle will adjust the PDB’s value to meet these requirements.

See Also:

SHARED_POOL_SIZE and Automatic Storage Management

On a database instance using Oracle Automatic Storage Management (Oracle ASM), additional memory is required to store extent maps. As a general guideline, you can aggregate the values from the following queries to obtain current database storage size that is either already on Oracle ASM or will be stored in Oracle ASM. Then determine the redundancy type that is used (or will be used), and calculate the value for SHARED_POOL_SIZE, using the aggregated value as input.

SELECT SUM(BYTES)/(1024*1024*1024) FROM V$LOGFILE a, V$LOG b
WHERE a.group#=b.group#;

Additionally, keep the following guidelines in mind:

  • For disk groups using external redundancy:

    (Every 100G of space needs 1M of extra shared pool) + 2M

  • For disk groups using normal redundancy:

    (Every 50G of space needs 1M of extra shared pool) + 4M

  • For disk groups using high redundancy:

    (Every 33G of space needs 1M of extra shared pool) + 6M