This section describes the options for shadowing in the Mimer SQL UTIL program.
Shadowing utilities are used to create or drop a shadow, transform a shadow to a master, list information about shadows and databanks, and enter or leave a program ident.
The shadowing utilities main menu looks like this:-- SHADOW utilities -- 1. Create shadow 2. Drop shadow 3. Transform shadow to master 4. List shadowing information 5. Enter program ident 6. Leave program ident 0. Exit
Where noted in the following descriptions, wildcard characters following the SQL standard can be used in databank names.
The percent character % represents one or more characters, and underscore _ represents one and only one character. Thus DB% means every databank name beginning with DB, and DB_ specifies all databank names that consist of the letters DB followed by one (and only one) alphanumeric character or blank space.
A percent character alone is shorthand for all databanks (excluding TRANSDB).
Creating a Shadow
When you select the Create shadow option, you are prompted for the name of the databank to be shadowed, the name for the new shadow, and the filename for the new shadow. For example, selecting Create shadow, option 1:Select: 1 -- Create shadow -- Databank name : hoteldb Create shadow for databank HOTELDB Shadow name : hoteldb_s Filename for shadow : /mnt/hoteldb_s.sdw Shadow HOTELDB_S created and copied from databank HOTELDB
When you select Drop shadow, you are prompted for the databank name for which a shadow should be dropped. Wildcard characters are allowed in the databank name. A listing of all shadows for the specified databank is displayed. Enter the name of the shadow you want to drop. For example, selecting Drop shadow, option 2:Select: 2 -- Drop shadow -- Databank name : hoteldb DATABANK SHADOW OFFLINE FILE ======================================== HOTELDB HOTELDB_S N /mnt/hoteldb_s.sdw --- One shadow found Name of shadow to drop (<CR> = skip): hoteldb_s Shadow HOTELDB_S dropped
Transforming a Shadow to Master
When the Transform shadow to master option is chosen from the Shadowing utilities you are prompted for the master databank name (wildcard characters are allowed).
After the name is entered, a listing of all shadows for the selected databanks is displayed. Select which shadow to transform by entering the shadow name.
For example, selecting Transform Shadow, option 3:Select: 3 -- Transform shadow -- Databank name : hoteldb DATABANK SHADOW OFFLINE FILE ======================================== HOTELDB HOTELDB_S Y /mnt/hoteldb_s.sdw --- One shadow found Name of shadow to transform (<CR> = skip): hoteldb_s Shadow HOTELDB_S is set online before it is transformed to master Shadow HOTELDB_S transformed to master
The old master databank file is usually deleted by the operating system. If it is not deleted, you can use operating system facilities to delete it.
Listing Shadowing Information
The List shadowing information option lists the following information for both master and shadow databanks: databank name, shadow name (if the databank is a shadow), offline status for the shadows (Y = Offline, N = Online) and the filename.
Enter the master databank's name that you want to list shadowing information for. Wildcard characters are allowed.
If you enter a carriage return <CR> without specifying a databank, shadow information for all databanks in the system is displayed. The listing is halted when the screen is full and you can decide whether to continue the listing or not.
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