HASH_AREA_SIZE

Property	Description
Parameter type	Integer
Default value	Derived: 2 * SORT_AREA_SIZE
Modifiable	ALTER SESSION
Range of values	0 to operating system-dependent
Basic	No

Note:

1. Oracle does not recommend using the HASH_AREA_SIZE parameter unless the instance is configured with the shared server option. Oracle recommends that you enable automatic sizing of SQL working areas by setting PGA_AGGREGATE_TARGET instead. HASH_AREA_SIZE is retained for backward compatibility.

HASH_AREA_SIZE is relevant to parallel execution operations and to the query portion of DML or DDL statements. It specifies the maximum amount of memory, in bytes, to be used for hash joins.

2. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter

where upper(name) = ‘HASH_AREA_SIZE’;

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE	ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
hash_area_size	131072	TRUE	TRUE	FALSE	FALSE	FALSE	size of in-memory hash work area

Oracle initializatoin parameters

GLOBAL_TXN_PROCESSES

Property	Description
Parameter type	Integer
Default value	1
Modifiable	ALTER SYSTEM
Range of values	1 to 20
Basic	No
Real Application Clusters	Multiple instances can have different values.

GLOBAL_TXN_PROCESSES specifies the initial number of GTXn background processes (GTX0, ... GTX9 and GTXa, ... GTXj) per instance to support global (XA) transactions in an Oracle RAC environment.

GLOBAL_TXN_PROCESSES is useful for systems that process global (XA) transactions heavily. You do not need to specify a value for this parameter since Oracle Database automatically determines the number of processes and autotunes them, as necessary. GTXn background processes are only seen in an Oracle RAC environment.

Note:

1. This parameter was introduced in 11g.

2. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter

where upper(name) = ‘GLOBAL_TXN_PROCESSES’;

Oracle initializatoin parameters

GLOBAL_NAMES

Property	Description
Parameter type	Boolean
Default value	false
Modifiable	ALTER SESSION, ALTER SYSTEM
Range of values	true | false
Basic	No

GLOBAL_NAMES specifies whether a database link is required to have the same name as the database to which it connects.

If the value of GLOBAL_NAMES is false, then no check is performed. If you use or plan to use distributed processing, then Oracle recommends that you set this parameter to true to ensure the use of consistent naming conventions for databases and links in a networked environment.

Note:

1. Related parameter: DB_DOMAIN

2. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter

where upper(name) = ‘GLOBAL_NAMES’;

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE	ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
global_names	FALSE	TRUE	TRUE	IMMEDIATE	TRUE	FALSE	enforce that database links have same name as remote database

Oracle initializatoin parameters

GLOBAL_CONTEXT_POOL_SIZE

Property	Description
Parameter type	String
Default value	1 MB
Modifiable	No
Range of values	Any integer value in MB
Basic	No

Note:

1. The GLOBAL_CONTEXT_POOL_SIZE parameter is deprecated. It is retained for backward compatibility only.

GLOBAL_CONTEXT_POOL_SIZE specifies the amount of memory to allocate in the SGA for storing and managing global application context.

2. This parameter was introduced in Oracle9i.

3. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter

where upper(name) = ‘GLOBAL_CONTEXT_POOL_SIZE’;

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE	ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
global_context_pool_size		TRUE	FALSE	FALSE	FALSE	TRUE	Global Application Context Pool Size in Bytes

Oracle initializatoin parameters

GCS_SERVER_PROCESSES

Property	Description
Parameter type	Integer
Default value	For one CPU, there will be one GCS server process. For 2 - 8 CPUs, there will be 2 GCS server processes. For more than 8 CPUs, the number of GCS server processes will be equal to the number of CPUs divided by 4. If the result includes a fraction, the fraction is disregarded. For example, if you had 10 CPUs, then 10/4 would mean 2 GCS processes.
Modifiable	No
Range of values	1 to 36
Basic	No
Real Application Clusters	Multiple instances can have different values.

GCS_SERVER_PROCESSES specifies the number of server processes in Global Cache Service (GCS) to serve the inter-instance traffic among Real Application Clusters (RAC) instances. GCS server processes are only seen in a RAC environment.

Note:

1. This parameter was introduced in 10g.

2. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter

where upper(name) = ‘GCS_SERVER_PROCESSES’;

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE	ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
gcs_server_processes	0	TRUE	FALSE	FALSE	FALSE	FALSE	number of background gcs server processes to start

Oracle initializatoin parameters

GC_FILES_TO_LOCKS

Property	Description
Parameter type	String
Syntax	GC_FILES_TO_LOCKS = '{file_list=lock_count[!blocks][EACH][:...]}' Spaces are not allowed within the quotation marks.
Default value	There is no default value.
Modifiable	No
Basic	No
Real Application Clusters	You must set this parameter for every instance, and multiple instances must have identical values. To change the value, you must shut down all instances in the cluster, change the value for each instance, and then start up each instance.

Note:

1. Setting this parameter to any value other than the default will disable Cache Fusion processing in a Real Application Clusters environment.

GC_FILES_TO_LOCKS is a Real Application Clusters parameter that has no effect on an instance running in exclusive mode. It controls the mapping of pre-release 9.0.1 parallel cache management (PCM) locks to datafiles.

Values:

· file_list

One or more datafiles listed by their file numbers, or ranges of file numbers, with comma separators:

filenumber[-filenumber][,filenumber[-filenumber]]...

To find the correspondence between filenames and file numbers, query the FILE_NAME and FILE_ID columns of the DBA_DATA_FILES data dictionary view.

· lock_count

The number of PCM locks assigned to file_list. By default these locks are fixed. If you set lock_count to 0, then Oracle uses fine-grain locking for these files and takes locks as needed from the pool of releasable locks.

· blocks

Specifies the number of contiguous blocks covered by one lock. The default is noncontiguous blocks.

· EACH

Indicates that each datafile in file_list is assigned a separate set of lock_count PCM locks.

The value of the parameter should be set to cover as many files as possible. Therefore, to avoid performance problems, you should always change GC_FILES_TO_LOCKS when the size of datafiles change or when new datafiles are added. Doing so requires you to shut down and restart your cluster database.

If the number of PCM locks allocated to a datafile is less than or equal to the number of blocks in a datafile, each of these locks will cover a number of contiguous blocks within the datafile equal to blocks. If the number of PCM locks assigned to the datafile is larger than its number of blocks, resources will be wasted because some locks will not be covering any blocks.

A colon (:) separates each clause that assigns a number of PCM locks to file_list.

2. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter

where upper(name) = ‘GC_FILES_TO_LOCKS’;

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE	ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
gc_files_to_locks		TRUE	FALSE	FALSE	FALSE	FALSE	mapping between file numbers and global cache locks

Oracle initializatoin parameters