【cognos】models format extensions pyi/pyj vs. mdl

http://www.cognos-bi.info/faq/cognos_model_file_types.htm

 

The PYH and PYI models are compiled to a binary format and are Cognos series 7 version specific. IBM Cognos 8 uses a PYJ file format. Models stored in the binary format are generally quicker to open and refresh.
MDL (Model Definition Language) file format is a model saved in an ASCII file (its structure can be understood pretty easily). It is compatible between different version of transformer and can be edited in any text editor. 
It takes more time to work with MDL files because when it is being opened, Transformer compiles it anyway in the background. 

The biggest difference between PYI/PYJ and MDL file is that in the binary PYI file stores passwords to the datasources(usually database connections) and MDL file contains only an userid and password needs to be provided every time the cube is refreshed. 

How to convert from a pyh to pyi or pyj model format? 
The easiest way to convert from PYH to PYI is to open the model in the earlier Cognos version (for instance PowerPlay Transformer 6), save it as an MDL file, then open it in the newer version of PowerPlay Transformer (version 7 or 8) and save into the PYI format which is native to that versions. 

It's recommended to keep powerplay models in both output formats (PYI and MDL) and use PYI for cube recreation and have MDL as a backup and for the modelling. 

The PowerPlay PowerCubes created from all model types are stored in the MDC format.