V$LATCH_PARENT

V$LATCH_PARENT displays statistics about parent latches. The columns of V$LATCH_PARENT are the same as those for V$LATCH.

Column	Datatype	Description
ADDR	RAW(4 | 8)	Address of the latch object
LATCH#	NUMBER	Latch number
LEVEL#	NUMBER	Latch level
NAME	VARCHAR2(64)	Latch name
HASH	NUMBER	Latch hash
GETS	NUMBER	Number of times the latch was requested in willing-to-wait mode
MISSES	NUMBER	Number of times the latch was requested in willing-to-wait mode and the requestor had to wait
SLEEPS	NUMBER	Number of times a willing-to-wait latch request resulted in a session sleeping while waiting for the latch
IMMEDIATE_GETS	NUMBER	Number of times a latch was requested in no-wait mode
IMMEDIATE_MISSES	NUMBER	Number of times a no-wait latch request did not succeed (that is, missed)
WAITERS_WOKEN	NUMBER	This column has been deprecated and is present only for compatibility with previous releases of Oracle. No data is accumulated for this column; it will always have a value of zero.
WAITS_HOLDING_LATCH	NUMBER	This column has been deprecated and is present only for compatibility with previous releases of Oracle. No data is accumulated for this column; it will always have a value of zero.
SPIN_GETS	NUMBER	Willing-to-wait latch requests which missed the first try but succeeded while spinning
SLEEP[1 | 2 | 3 | 4]	NUMBER	These columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for these columns; they will always have a value of zero. As a substitute for this column you can query the appropriate rows of the V$EVENT_HISTOGRAM view where the EVENT column has a value of latch free or latch:%.
SLEEP[5 | 6 | 7 | 8 | 9 | 10 | 11]	NUMBER	These columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for these columns.
WAIT_TIME	NUMBER	Elapsed time spent waiting for the latch (in microseconds)

See Also: "V$LATCH"

Oracle data dictionary views

Oracle dynamic performance views

V$LATCH

V$LATCH displays aggregate latch statistics for both parent and child latches, grouped by latch name. Individual parent and child latch statistics are broken down in the views V$LATCH_PARENT and V$LATCH_CHILDREN.

Column	Datatype	Description
ADDR	RAW(4 | 8)	Address of the latch object
LATCH#	NUMBER	Latch number
LEVEL#	NUMBER	Latch level
NAME	VARCHAR2(64)	Latch name
HASH	NUMBER	Latch hash
GETS	NUMBER	Number of times the latch was requested in willing-to-wait mode
MISSES	NUMBER	Number of times the latch was requested in willing-to-wait mode and the requestor had to wait
SLEEPS	NUMBER	Number of times a willing-to-wait latch request resulted in a session sleeping while waiting for the latch
IMMEDIATE_GETS	NUMBER	Number of times a latch was requested in no-wait mode
IMMEDIATE_MISSES	NUMBER	Number of times a no-wait latch request did not succeed (that is, missed)
WAITERS_WOKEN	NUMBER	This column has been deprecated and is present only for compatibility with previous releases of Oracle. No data is accumulated for this column; it will always have a value of zero.
WAITS_HOLDING_LATCH	NUMBER	This column has been deprecated and is present only for compatibility with previous releases of Oracle. No data is accumulated for this column; it will always have a value of zero.
SPIN_GETS	NUMBER	Willing-to-wait latch requests which missed the first try but succeeded while spinning
SLEEP[1 | 2 | 3 | 4]	NUMBER	These columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for these columns; they will always have a value of zero. As a substitute for this column you can query the appropriate rows of the V$EVENT_HISTOGRAM view where the EVENT column has a value of latch free or latch:%.
SLEEP[5 | 6 | 7 | 8 | 9 | 10 | 11]	NUMBER	These columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for these columns.
WAIT_TIME	NUMBER	Elapsed time spent waiting for the latch (in microseconds)

See Also:

• "V$LATCH_CHILDREN"
• "V$LATCH_PARENT"

Oracle data dictionary views

Oracle dynamic performance views

SERVICE_NAMES

Property	Description
Parameter type	String
Syntax	SERVICE_NAMES = db_service_name [, db_service_name [ ... ] ]
Default value	DB_UNIQUE_NAME.DB_DOMAIN if defined
Modifiable	ALTER SYSTEM
Range of values	Any ASCII string or comma-separated list of string names
Basic	No
Real Application Clusters	Do not set the SERVER_NAMES parameter for Real Application Clusters (RAC). Instead, define services using Database Configuration Assistant (DBCA) and manage services using Server Control (SRVCTL) utility.

SERVICE_NAMES specifies one or more names by which clients can connect to the instance. The instance registers its service names with the listener. When a client requests a service, the listener determines which instances offer the requested service and routes the client to the appropriate instance.

You can specify multiple service names in order to distinguish among different uses of the same database. For example:

SERVICE_NAMES = sales.acme.com, widgetsales.acme.com

You can also use service names to identify a single service that is available from two different databases through the use of replication.

If you do not qualify the names in this parameter with a domain, Oracle qualifies them with the value of the DB_DOMAIN parameter. If DB_DOMAIN is not specified, then no domain will be applied to the non-qualified SERVICE_NAMES values.

See Also:

• Oracle Database Net Services Administrator's Guide for more information on this parameter and its settings
• Oracle Real Application Clusters Administration and Deployment Guide for information about defining and administering services in a RAC environment
• "DB_DOMAIN"

Note:

1. Clients wishing to connect to a SERVICE should use CONNECT_DATA which includes a SERVICE_NAME attribute rather than a SID. eg: (CONNECT_DATA=(SERVICE_NAME=widgetsales.acme.com))

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) = 'SERVICE_NAMES';

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE		ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
service_names	mydb.mycom.com	TRUE	FALSE	IMMEDIATE	TRUE		FALSE	service names supported by the instance

Oracle initializatoin parameters