SHARED_POOL_SIZE specifies (in bytes) the size of the shared pool.
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 indicates a possible minimum value for the PDB usage of the memory pool.
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 set at the CDB level, then the following requirement must be met:
The value of SHARED_POOL_SIZE set in a PDB must be less than or equal to 50% of the SGA_TARGET value at the CDB level.
If the SGA_TARGET initialization parameter is set at the PDB level, then the following requirement must be met:
The value of SHARED_POOL_SIZE set in a PDB must be less than or equal to 50% of the SGA_TARGET value at the PDB 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 requirement 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.
When you set SHARED_POOL_SIZE in a PDB to a value that does not meet these requirements, you receive an error.
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.
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
