How To Install Dbms Lock Package

• How To Install Dbms Lock Package System
• How To Install Dbms Lock Package Without
• How To Use Dbm Timer

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:

I am trying to write a small bit of PL/SQL that has a non-CPU burning sleep in it. The following works in sqldeveloper begin dbmslock.sleep(5); end; BUT (as the same user), I can't do the fol. Select the Tools NuGet Package Manager Package Manager Console menu command. Once the console opens, check that the Default project drop-down list shows the project into which you want to install the package. If you have a single project in the solution, it is already selected. Enter the command Install-Package Newtonsoft.Json (see Install.

The Oracle schema or user does not have access to the DBMSLOCK package. Environment The issue is seen when you have a newly created or a migrated IBM Business Process Manager V7.5 profile with Oracle as the back-end database.

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

How To Install Dbms Lock Package System

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

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

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

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

Return Values

Table 53-6 CONVERT Function Return Values

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

Return Values

Table 53-8 RELEASE Function Return Values

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.

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

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

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

Return Values

Table 53-6 CONVERT Function Return Values

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

Return Values

Table 53-8 RELEASE Function Return Values

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

Return Values

Table 53-10 REQUEST Function Return Values

SLEEP Procedure

This procedure suspends the session for a given period of time.

Syntax

Parameters

Table 53-11 SLEEP Procedure Parameters

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.

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 Guide

94.1 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

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

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

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

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

Return Values

Table 94-6 CONVERT Function Return Values

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.

Wheel of fortune slot app. Parameters

Table 94-7 RELEASE Function Parameter

How To Install Dbms Lock Package Without

Return Values

Table 94-8 RELEASE Function Return Values

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.

Parameters

Table 94-9 REQUEST Function Parameters

Return Values

Table 94-10 REQUEST Function Return Values

How To Use Dbm Timer