SHARED_POOL_SIZE

Property	Description
Parameter type	Big integer
Syntax	`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 ASM, see "SHARED_POOL_SIZE and Automatic Storage Management".
Modifiable	`ALTER SYSTEM`
Range of values	Minimum: the granule size Maximum: operating system-dependent

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 you set PARALLEL_AUTOMATIC_TUNING to false, then Oracle also allocates parallel execution message buffers from the shared pool. Larger values improve performance in multi-user systems. Smaller values use less memory.

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

See Also:

Oracle Database Performance Tuning Guide for more information on setting this parameter
Oracle Database Upgrade Guide for information on parallel execution message buffers
"PARALLEL_AUTOMATIC_TUNING" and "V$SGASTAT"

SHARED_POOL_SIZE and Automatic Storage Management

On a database instance using 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 ASM or will be stored in 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$DATAFILE;
SELECT SUM(BYTES)/(1024*1024*1024) FROM V$LOGFILE a, V$LOG b
WHERE a.group#=b.group#;
SELECT SUM(BYTES)/(1024*1024*1024) FROM V$TEMPFILE WHERE
status='ONLINE';

Additionally, keep the following guidelines in mind:

For diskgroups using external redundancy:

(Every 100G of space needs 1M of extra shared pool) + 2M
For diskgroups using normal redundancy:

(Every 50G of space needs 1M of extra shared pool) + 4M
For diskgroups using high redundancy:

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