The CLONE command creates a new, empty file with the same file specifications as an existing file (including any supplemental indexes, but excluding the owner name). The new data file includes all the defined key characteristics (such as key position, key length, or duplicate key values) contained in the existing file.
The CLONE command ignores all MicroKernel configuration options that affect file statistics (such as
System Data)
except file version. The
CLONE command creates a new file using the database engine file version you specify with the
Create File Version option.
Btrieve 6.0 and later allows a maximum of 23 key segments in a data file with a page size of 1,024 bytes. Therefore, the CLONE command sets the page size in the new data file to 2,048 bytes if the existing data file contains 24 key segments and has a page size of 1,024 bytes. This occurs if the existing data file has a format earlier than 6.0 and the database engine was not loaded with the
Create File Version option set to 5.
x or 6.
x.
If you are cloning a pre-7.x file, ensure that the database engine is configured to create the file format version that you want the new file to be. For example, if you want to clone a 6.15 file in 9.5 format, ensure that the
MicroKernel File Format Version option is set to
9.5.
The CLROWNER command clears the owner name of a MicroKernel file.
The CREATE command generates an empty MicroKernel file using the characteristics you specify in a description file. Before you can use the
CREATE command, you must create a description file to specify the new key characteristics. For more information, see
Description Files.
The sample description file shown in Figure 34 creates a MicroKernel formatted file. The file is specified to have a page size of 512 bytes and 2 keys. The fixed-length portion of each record in the file is set to 98 bytes. The file specifies variable-length records with no blank truncation, record compression, and variable-tail allocation tables (VATs). The free space threshold is set to 20 percent. Allocation is set to 100 pages. The MicroKernel preallocates 100 pages, or 51,200 bytes, when it creates the file.
The DROP command removes an index from a file and adjusts the key numbers of any remaining indexes, subtracting 1 from each subsequent key number. If you do not want to renumber the keys, you can add 128 to the key number you specify to be dropped. This renumbering feature is available only for 6.0 and later files.
In the first example, the BUTIL -DROP command drops key number 1 from the COURSE.MKD file and renumbers the remaining key numbers as 0 and 1.
In the following example, the BUTIL –DROP command drops key number 1, but does not renumber the keys. The key numbers remain 0 and 2.
The INDEX command builds an external index file for an existing MicroKernel file, based on a field not previously specified as a key in the existing file. Before you can use the
INDEX command, you must create a description file to specify the new key characteristics. For more information about description files, see
Description Files.
The INDEX command creates the external index file and then displays the number of records that were indexed. To retrieve the data file’s records using the external index file, use the
Save command.
The SETOWNER command sets an owner name for a data file.
The SINDEX command creates an additional index for an existing MicroKernel file. By default, the key number of the new index is one higher than the previous highest key number for the data file, or you can instruct the database engine to use a specific key number. An exception is if a
DROP command previously removed an index without renumbering the remaining keys, thus producing an unused key number; in this case, the new index receives the first unused number.
If you do not use the SYSKEY option with this command, you must create a description file that defines key specifications for the index before you can use the
SINDEX command. For more information about description files, see
Description Files.
You can use several commands in the BUTIL (Clone,
Recover, and
Load, respectively) to remove unused space in a data file to decrease its size.
Caution: No two files can share the same file name and differ only in their file name extension if both files are in the same directory. For example, do not name a data file Invoice.btr and another one Invoice.mkd in the same directory. This restriction applies because the database engine uses the file name for various areas of functionality while ignoring the file name extension. Since only the file name is used to differentiate files, files that differ only in their file name extension look identical to the database engine. 
Note: 
