After installing and when creating a connection, the default username is SYSTEM and use the password created in the step sudo /etc/init.d/oracle-xe configure In gnome classic - The menus for Oracle are under Other, sqldeveloper is under Programming. For this installation, you need either the DVDs or a downloaded version of the DVDs. In this tutorial, you install from the downloaded version. From the directory where the DVD files were unzipped, open Windows Explorer and double-click on setup.exe from the db Disk1 directory. The product you want to install is Oracle Database 11g.
- How To Install Dbms Lock Package In Excel
- How To Install Dbm Classic
- Dbms Lock Must Be Declared
- How To Install Dbms Lock Package In Java
The
DBMS_LOCK
package provides an interface to Oracle Lock Management services. You can request a lock of a specific mode, give it a unique name recognizable in another procedure in the same or another instance, change the lock mode, and release it.See Also:
For more information, and an example of how to use the DBMS_LOCK
package, see 'About User Locks' in Oracle Database Application Developer's Guide - FundamentalsHow To Install Dbms Lock Package In Excel
This chapter contains the following topics:
- Overview
- Security Model
- Constants
- Rules and Limits
- Operational Notes
Using DBMS_LOCK
Overview
Some uses of user locks:
- Providing exclusive access to a device, such as a terminal
- Providing application-level enforcement of read locks
- Detecting when a lock is released and cleanup after the application
- Synchronizing applications and enforcing sequential processing
Security Model
There might be operating system-specific limits on the maximum number of total locks available. This must be considered when using locks or making this package available to other users. Consider granting the
EXECUTE
privilege only to specific users or roles.A better alternative would be to create a cover package limiting the number of locks used and grant
EXECUTE
privilege to specific users. An example of a cover package is documented in the DBMS_LOCK.SQL
package specification file. The abbreviations for these locks as they appear in Enterprise Manager monitors are in parentheses.Constants
The
DBMS_LOCK
package uses the constants shown in Table 53-1.Table 53-1 DBMS_LOCK Constants
Name | Alternate Name(s) | Type | Value | OEM Abbreviation | Description |
---|---|---|---|---|---|
NL_MODE | NuL1 | INTEGER | 1 | - | - |
SS_MODE | Sub Shared | INTEGER | 2 | ULRS | This can be used on an aggregate object to indicate that share locks are being acquired on subparts of the object. |
SX_MODE |
| INTEGER | 3 | ULRX | This can be used on an aggregate object to indicate that exclusive locks are being acquired on sub-parts of the object. |
S_MODE |
| INTEGER | 4 | ULRSX | - |
SSX_MODE |
| INTEGER | 5 | - | This indicates that the entire aggregate object has a share lock, but some of the sub-parts may additionally have exclusive locks. |
X_MODE | Exclusive | INTEGER | 6 | ULX | - |
These are the various lock modes (nl -> 'NuLl', ss -> 'Sub Shared', sx -> 'Sub eXclusive', s -> 'Shared', ssx -> 'Shared Sub eXclusive', x -> 'eXclusive').
Rules and Limits
When another process holds 'held', an attempt to get 'get' does the following:
Table 53-2 Lock Compatibility
HELD MODE | GET NL | GET SS | GET SX | GET S | GET SSX | GET X |
---|---|---|---|---|---|---|
NL | Success | Success | Success | Success | Success | Success |
SS | Success | Success | Success | Success | Success | Fail |
SX | Success | Success | Success | Fail | Fail | Fail |
S | Success | Success | Fail | Success | Fail | Fail |
SSX | Success | Success | Fail | Fail | Fail | Fail |
X | Success | Fail | Fail | Fail | Fail | Fail |
The constant
maxwait
waits forever.Operational Notes
User locks never conflict with Oracle locks because they are identified with the prefix 'UL'. You can view these locks using the Enterprise Manager lock monitor screen or the appropriate fixed views. User locks are automatically released when a session terminates.The lock identifier is a number in the range of 0 to 1073741823.
Because a reserved user lock is the same as an Oracle lock, it has all the functionality of an Oracle lock, such as deadlock detection. Be certain that any user locks used in distributed transactions are released upon
COMMIT
, or an undetected deadlock may occur.DBMS_LOCK
is most efficient with a limit of a few hundred locks for each session. Oracle strongly recommends that you develop a standard convention for using these locks in order to avoid conflicts among procedures trying to use the same locks. For example, include your company name as part of your lock names.Summary of DBMS_LOCK Subprograms
Table 53-3 DBMS_LOCK Package Subprograms
Subprogram | Description |
---|---|
Allocates a unique lock ID to a named lock. | |
Converts a lock from one mode to another. | |
Releases a lock. | |
Requests a lock of a specific mode. | |
Puts a procedure to sleep for a specific time. |
ALLOCATE_UNIQUE Procedure
This procedure allocates a unique lock identifier (in the range of 1073741824 to 1999999999) given a lock name. Lock identifiers are used to enable applications to coordinate their use of locks. This is provided because it may be easier for applications to coordinate their use of locks based on lock names rather than lock numbers.
Syntax
Parameters
Table 53-4 ALLOCATE_UNIQUE Procedure Parameters
Parameter | Description |
---|---|
lockname | Name of the lock for which you want to generate a unique ID. Do not use lock names beginning with ORA$ ; these are reserved for products supplied by Oracle. |
lockhandle | Returns the handle to the lock ID generated by ALLOCATE_UNIQUE .You can use this handle in subsequent calls to REQUEST , CONVERT , and RELEASE .A handle is returned instead of the actual lock ID to reduce the chance that a programming error accidentally creates an incorrect, but valid, lock ID. This provides better isolation between different applications that are using this package. LOCKHANDLE can be up to VARCHAR2 (128).All sessions using a lock handle returned by ALLOCATE_UNIQUE with the same lock name are referring to the same lock. Therefore, do not pass lock handles from one session to another. |
expiration_specs | Number of seconds to wait after the last ALLOCATE_UNIQUE has been performed on a given lock, before permitting that lock to be deleted from the DBMS_LOCK_ALLOCATED table.The default waiting period is 10 days. You should not delete locks from this table. Subsequent calls to ALLOCATE_UNIQUE may delete expired locks to recover space. |
Usage Notes
If you choose to identify locks by name, you can use
ALLOCATE_UNIQUE
to generate a unique lock identification number for these named locks.The first session to call
ALLOCATE_UNIQUE
with a new lock name causes a unique lock ID to be generated and stored in the dbms_lock_allocated
table. Subsequent calls (usually by other sessions) return the lock ID previously generated.A lock name is associated with the returned lock ID for at least
expiration_secs
(defaults to 10 days) past the last call to ALLOCATE_UNIQUE
with the given lock name. After this time, the row in the dbms_lock_allocated
table for this lock name may be deleted in order to recover space. ALLOCATE_UNIQUE
performs a commit.Note:
Named user locks may be less efficient, because Oracle uses SQL to determine the lock associated with a given name.
Exceptions
ORA-20000
, ORU-10003:
Unable to find or insert lock <lockname
> into catalog dbms_lock_allocated
.CONVERT Function
This function converts a lock from one mode to another.
CONVERT
is an overloaded function that accepts either a user-defined lock identifier, or the lock handle returned by the ALLOCATE_UNIQUE
procedure.Syntax
Parameters
Table 53-5 CONVERT Function Parameters
Parameter | Description |
---|---|
id or lockhandle | User assigned lock identifier, from 0 to 1073741823, or the lock handle, returned by ALLOCATE_UNIQUE , of the lock mode you want to change. |
lockmode | New mode that you want to assign to the given lock. For the available modes and their associated integer identifiers, see Constants. |
timeout | Number of seconds to continue trying to change the lock mode. If the lock cannot be converted within this time period, then the call returns a value of 1 (timeout). |
Return Values
Table 53-6 CONVERT Function Return Values
Return Value | Description |
---|---|
0 | Success |
1 | Timeout |
2 | Deadlock |
3 | Parameter error |
4 | Don't own lock specified by id or lockhandle |
5 | Illegal lock handle |
RELEASE Function
This function explicitly releases a lock previously acquired using the
REQUEST
function. Locks are automatically released at the end of a session. RELEASE
is an overloaded function that accepts either a user-defined lock identifier, or the lock handle returned by the ALLOCATE_UNIQUE
procedure.Syntax
Parameters
Table 53-7 RELEASE Function Parameter
Parameter | Description |
---|---|
id or lockhandle | User assigned lock identifier, from 0 to 1073741823, or the lock handle, returned by ALLOCATE_UNIQUE , of the lock mode you want to change. |
Return Values
Steep full game free pc play. steep for mac. Table 53-8 RELEASE Function Return Values
Return Value | Description |
---|---|
0 | Success |
3 | Parameter error |
4 | Do not own lock specified by id or lockhandle |
5 | Illegal lock handle |
REQUEST Function
This function requests a lock with a given mode.
REQUEST
is an overloaded function that accepts either a user-defined lock identifier, or the lock handle returned by the ALLOCATE_UNIQUE
procedure.Syntax
The current default values, such as
X_MODE
and MAXWAIT
, are defined in the DBMS_LOCK
package specification.Parameters
Table 53-9 REQUEST Function Parameters
Parameter | Description |
---|---|
id or lockhandle | User assigned lock identifier, from 0 to 1073741823, or the lock handle, returned by ALLOCATE_UNIQUE , of the lock mode you want to change. |
lockmode | Mode that you are requesting for the lock. For the available modes and their associated integer identifiers, see Constants. |
timeout | Number of seconds to continue trying to grant the lock. If the lock cannot be granted within this time period, then the call returns a value of 1 ( timeout ). |
release_on_commit | Set this parameter to TRUE to release the lock on commit or roll-back.Otherwise, the lock is held until it is explicitly released or until the end of the session. |
Return Values
Table 53-10 REQUEST Function Return Values
Return Value | Description |
---|---|
0 | Success |
1 | Timeout |
2 | Deadlock |
3 | Parameter error |
4 | Already own lock specified by id or lockhandle |
5 | Illegal lock handle |
SLEEP Procedure
This procedure suspends the session for a given period of time.
Syntax
Parameters
Table 53-11 SLEEP Procedure Parameters
Parameter | Description |
---|---|
seconds | Amount of time, in seconds, to suspend the session. The smallest increment can be entered in hundredths of a second; for example, 1.95 is a legal time value. |
The
DBMS_LOCK
package provides an interface to Oracle Lock Management services. How To Install Dbm Classic
You can request a lock of a specific mode, give it a unique name recognizable in another procedure in the same or another instance, change the lock mode, and release it.
This chapter contains the following topics:
See Also:
For more information, and an example of how to use the
DBMS_LOCK
package, Oracle Database Development Guide94.1 DBMS_LOCK Overview
The
DBMS_LOCK
package has many beneficial uses. These uses include the following:
- Providing exclusive access to a device, such as a terminal
- Providing application-level enforcement of read locks
- Detecting when a lock is released and cleanup after the application
- Synchronizing applications and enforcing sequential processing
94.2 DBMS_LOCK Security Model
There might be operating system-specific limits on the maximum number of total locks available. This must be considered when using locks or making this package available to other users. Consider granting the
EXECUTE
privilege only to specific users or roles. A better alternative would be to create a cover package limiting the number of locks used and grant
EXECUTE
privilege to specific users. An example of a cover package is documented in the DBMS_LOCK.SQL
package specification file. The abbreviations for these locks as they appear in Enterprise Manager monitors are in parentheses. 94.3 DBMS_LOCK Constants
The
DBMS_LOCK
package includes several constants to use when specifying parameter values. These constants are shown in the following table.
Table 94-1 DBMS_LOCK Constants
Name | Alternate Name(s) | Type | Value | OEM Abbreviation | Description |
---|---|---|---|---|---|
NL_MODE | NuL1 | INTEGER | 1 | - | - |
Golden electric scooter repair manual. SS_MODE | Sub Shared | INTEGER | 2 | ULRS | This can be used on an aggregate object to indicate that share locks are being acquired on subparts of the object. |
SX_MODE |
| INTEGER | 3 | ULRX | This can be used on an aggregate object to indicate that exclusive locks are being acquired on sub-parts of the object. |
S_MODE |
| INTEGER | 4 | ULRSX | - |
SSX_MODE |
| INTEGER | 5 | - | This indicates that the entire aggregate object has a share lock, but some of the sub-parts may additionally have exclusive locks. |
X_MODE | Exclusive | INTEGER | 6 | ULX | - |
These are the various lock modes (nl -> 'NuLl', ss -> 'Sub Shared', sx -> 'Sub eXclusive', s -> 'Shared', ssx -> 'Shared Sub eXclusive', x -> 'eXclusive').
94.4 DBMS_LOCK. Rules and Limits
When another process holds 'held', an attempt to get 'get' succeeds or fails, based on the held mode and type of get.
Table 94-2 Lock Compatibility
HELD MODE | GET NL | GET SS | GET SX | GET S | GET SSX | GET X |
---|---|---|---|---|---|---|
NL | Success | Success | Success | Success | Success | Success |
SS | Success | Success | Success | Success | Success | Fail |
SX | Success | Success | Success | Fail | Fail | Fail |
S | Success | Success | Fail | Success | Fail | Fail |
SSX | Success | Success | Fail | Fail | Fail | Fail |
X | Success | Fail | Fail | Fail | Fail | Fail |
94.5 DBMS_LOCK Operational Notes
User locks never conflict with Oracle locks because they are identified with the prefix 'UL'. You can view these locks using the Enterprise Manager lock monitor screen or the appropriate fixed views.
User locks are automatically released when a session terminates. The lock identifier is a number in the range of 0 to 1073741823.
Because a reserved user lock is the same as an Oracle lock, it has all the functionality of an Oracle lock, such as deadlock detection. Be certain that any user locks used in distributed transactions are released upon
COMMIT
, or an undetected deadlock may occur. DBMS_LOCK
is most efficient with a limit of a few hundred locks for each session. Oracle strongly recommends that you develop a standard convention for using these locks in order to avoid conflicts among procedures trying to use the same locks. For example, include your company name as part of your lock names.94.6 Summary of DBMS_LOCK Subprograms
This table lists the
DBMS_LOCK
subprograms and briefly describes them. Table 94-3 DBMS_LOCK Package Subprograms
Subprogram | Description |
---|---|
Allocates a unique lock ID to a named lock | |
Converts a lock from one mode to another | |
Releases a lock | |
Requests a lock of a specific mode. |
94.6.1 ALLOCATE_UNIQUE Procedure
This procedure allocates a unique lock identifier (in the range of 1073741824 to 1999999999) a specified lock name. Lock identifiers are used to enable applications to coordinate their use of locks. This is provided because it may be easier for applications to coordinate their use of locks based on lock names rather than lock numbers.
Parameters
Table 94-4 ALLOCATE_UNIQUE Procedure Parameters
Parameter | Description |
---|---|
lockname | Name of the lock for which you want to generate a unique ID. Do not use lock names beginning with ORA$ ; these are reserved for products supplied by Oracle. |
lockhandle | Returns the handle to the lock ID generated by ALLOCATE_UNIQUE . You can use this handle in subsequent calls to REQUEST , CONVERT , and RELEASE . A handle is returned instead of the actual lock ID to reduce the chance that a programming error accidentally creates an incorrect, but valid, lock ID. This provides better isolation between different applications that are using this package. LOCKHANDLE can be up to VARCHAR2 (128). All sessions using a lock handle returned by ALLOCATE_UNIQUE with the same lock name are referring to the same lock. Therefore, do not pass lock handles from one session to another. |
expiration_specs | Number of seconds to wait after the last ALLOCATE_UNIQUE has been performed on a specified lock, before permitting that lock to be deleted from the DBMS_LOCK_ALLOCATED table. The default waiting period is 10 days. You should not delete locks from this table. Subsequent calls to ALLOCATE_UNIQUE may delete expired locks to recover space. |
Usage Notes
If you choose to identify locks by name, you can use
ALLOCATE_UNIQUE
to generate a unique lock identification number for these named locks. The first session to call
ALLOCATE_UNIQUE
with a new lock name causes a unique lock ID to be generated and stored in the dbms_lock_allocated
table. Subsequent calls (usually by other sessions) return the lock ID previously generated. A lock name is associated with the returned lock ID for at least
expiration_secs
(defaults to 10 days) past the last call to ALLOCATE_UNIQUE
with the specified lock name. After this time, the row in the dbms_lock_allocated
table for this lock name may be deleted in order to recover space. ALLOCATE_UNIQUE
performs a commit. WARNING:
Named user locks may be less efficient, because Oracle uses SQL to determine the lock associated with a specified name.
Exceptions
ORA-20000
, ORU-10003:
Unable to find or insert lock <lockname
> into catalog dbms_lock_allocated
. 94.6.2 CONVERT Function
This function converts a lock from one mode to another.
CONVERT
is an overloaded function that accepts either a user-defined lock identifier, or the lock handle returned by the ALLOCATE_UNIQUE
procedure. Parameters
Table 94-5 CONVERT Function Parameters
Parameter | Description |
---|---|
id or lockhandle | User assigned lock identifier, from 0 to 1073741823, or the lock handle, returned by ALLOCATE_UNIQUE , of the lock mode you want to change |
lockmode | New mode that you want to assign to the specified lock. For the available modes and their associated integer identifiers, see Constants. |
timeout | Number of seconds to continue trying to change the lock mode. If the lock cannot be converted within this time period, then the call returns a value of 1 (timeout). |
Return Values
Table 94-6 CONVERT Function Return Values
Return Value | Description |
---|---|
0 | Success |
1 | Timeout |
2 | Deadlock |
3 | Parameter error |
4 | Don't own lock specified by id or lockhandle |
5 | Illegal lock handle |
94.6.3 RELEASE Function
This function explicitly releases a lock previously acquired using the
REQUEST
function. Locks are automatically released at the end of a session.
RELEASE
is an overloaded function that accepts either a user-defined lock identifier, or the lock handle returned by the ALLOCATE_UNIQUE
procedure. Parameters
Table 94-7 RELEASE Function Parameter
Parameter | Description |
---|---|
id or lockhandle | User assigned lock identifier, from 0 to 1073741823, or the lock handle, returned by ALLOCATE_UNIQUE , of the lock mode you want to change |
Return Values
Table 94-8 RELEASE Function Return Values
Return Value | Description |
---|---|
0 | Success |
3 | Parameter error |
4 | Do not own lock specified by id or lockhandle |
5 | Illegal lock handle |
94.6.4 REQUEST Function
This function requests a lock with a specified mode.
REQUEST
is an overloaded function that accepts either a user-defined lock identifier, or the lock handle returned by the ALLOCATE_UNIQUE
procedure. Syntax
The current default values, such as
X_MODE
and MAXWAIT
, are defined in the DBMS_LOCK
package specification. Dbms Lock Must Be Declared
Parameters
Table 94-9 REQUEST Function Parameters
How To Install Dbms Lock Package In Java
Parameter | Description |
---|---|
id or lockhandle | User assigned lock identifier, from 0 to 1073741823, or the lock handle, returned by ALLOCATE_UNIQUE , of the lock mode you want to change |
lockmode | Mode that you are requesting for the lock. For the available modes and their associated integer identifiers, see Constants. |
timeout | Number of seconds to continue trying to grant the lock. If the lock cannot be granted within this time period, then the call returns a value of 1 ( timeout ). |
release_on_commit | Set this parameter to TRUE to release the lock on commit or roll-back. Otherwise, the lock is held until it is explicitly released or until the end of the session. |
![Install Install](https://docs.oracle.com/cd/E16754_01/doc.75/e16710/img/rlo_install_config.gif)
Return Values
Table 94-10 REQUEST Function Return Values
Return Value | Description |
---|---|
0 | Success |
1 | Timeout |
2 | Deadlock |
3 | Parameter error |
4 | Already own lock specified by id or lockhandle |
5 | Illegal lock handle |