FirebirdSQL logo
 DATABASEDOMAIN 

AUTO | MANUAL Modes

When a shadow is converted to a database, it becomes unavailable.A shadow might alternatively become unavailable because someone accidentally deletes its file, or the disk space where the shadow files are stored is exhausted or is itself damaged.

  • If the AUTO mode is selected (the default value), shadowing ceases automatically, all references to it are deleted from the database header, and the database continues functioning normally.

    If the CONDITIONAL option was set, the system will attempt to create a new shadow to replace the lost one.It does not always succeed, however, and a new one may need to be created manually.

  • If the MANUAL mode attribute is set when the shadow becomes unavailable, all attempts to connect to the database and to query it will produce error messages.The database will remain inaccessible until either the shadow again becomes available, or the database administrator deletes it using the DROP SHADOW statement.MANUAL should be selected if continuous shadowing is more important than uninterrupted operation of the database.

Options for CREATE SHADOW

LENGTH

Specifies the maximum size of the primary or secondary shadow file in pages.The LENGTH value does not affect the size of the only shadow file, nor the last if it is a set.The last (or only) file will keep automatically growing as long as it is necessary.

STARTING AT

Specifies the shadow page number at which the next shadow file should start.The system will start adding new data to the next shadow file when the previous file is filled with data up to the specified page number.

Tip

You can verify the sizes, names and location of the shadow files by connecting to the database using isql and running the command SHOW DATABASE;