The qmidx Utility

The qmidx Utility

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The QM file system supports alternate key indices for retrieval of data based on the content of a non-key field. Normally, these indices reside in the directory that represents the data file. This helps to ensure that the entire file and its indices are handled as a single item when performing backup and restore operations

 

Sometimes it may be useful to place the indices elsewhere. This could be to improve load balancing across multiple disk drives or to simplify exclusion of large indices from backups since they can always be recreated from the data file. This separation of the indices from the data can be achieved using the PATHNAME option of the CREATE.INDEX or MAKE.INDEX commands when the first index is created.

 

The qmidx program is an operating system level command that allows users to report or modify the location of the indices. It has four modes of operation:

 

qmidx -d data.pathDeletes all indices for the named file.

 

qmidx -m data.path index.pathMoves the indices for the named file to the new location specified by index.path. If the index path is omitted, the indices are returned to their default location in the directory identified by data.path.

 

qmidx -p data.path index.pathSets the index path for the given data file. This operation is required after use of an operating system level tool to copy or move a data file to a new location. Failure to perform this step when duplicating a file may result in any changes to the copied file updating the indices of the original file.

 

qmidx -q data.pathDisplays the location of the indices for the given data file.

 

 

This program must only be used when the file is not in use. Failure to adhere to this rule may lead to data corruption or process failure.