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derby.database.forceDatabaseLock

<< derby.database.defaultConnectionMode | derby.database.noAutoBoot >>

Derby Reference Manual

364

fullAccess

Dynamic or static

Dynamic. Current connections are not affected, but all future connections are affected.
For information about dynamic changes to properties, see

Dynamic and static properties

derby.database.forceDatabaseLock

Function

On some platforms, if set to true, prevents Derby from booting a database if a db.lck file
is present in the database directory.

Derby attempts to prevent two JVMs from accessing a database at one time (and
potentially corrupting it) with the use of a file called db.lck in the database directory. On
some operating systems, the use of a lock file does not guarantee single access, and
so Derby only issues a warning and might allow multiple JVM access even when the file
is present. (For more information, see "Double-booting system behavior" in the Derby
Developer's Guide.)

Derby provides the property derby.database.forceDatabaseLock for use on platforms
that do not provide the ability for Derby to guarantee single JVM access. By default,
this property is set to false. When this property is set to true, if Derby finds the db.lck
file when it attempts to boot the database, it throws an exception and does not boot the
database.

Note: This situation can occur even when no other JVMs are accessing the database;
in that case, remove the db.lck file by hand in order to boot the database. If the db.lck file
is removed by hand while a JVM is still accessing a Derby database, there is no way for
Derby to prevent a second VM from starting up and possibly corrupting the database. In
this situation no warning message is logged to the error log.

Default

False.

Example

derby.database.forceDatabaseLock=true

Dynamic or static

This property is static; if you change it while Derby is running, the change does not take
effect until you reboot.

derby.database.fullAccessUsers

Function

One of the user authorization properties. Specifies a list of users to which full (read-write)
access to a database is granted. The list consists of user names separated by commas.
Do not put spaces after commas.

When set as a system property, specifies a list of users for which full access to all the
databases in the system is granted.