InfoSphere Datastage – How to Improve Sequential File Performance Using Parallel Environment Variables

APT_FILE_EXPORT_BUFFER_SIZE and APT_FILE_IMPORT_BUFFER_SIZE in DataStage Administrator
APT_FILE_EXPORT_BUFFER_SIZE and APT_FILE_IMPORT_BUFFER_SIZE in DataStage Administrator

While extensive use of sequential files is not best practice, sometimes there is no way around it, due to legacy systems and/or existing processes. However, recently, I have encountered a number of customers who are seeing significant performance issues with sequential file intensive processes. Sometimes it’s the job design, but often when you look at the project configuration they still have the default values. This is a quick and easy thing to check and to adjust to get a quick performance win, if they’ve not already been adjusted.These are delivered variables, but should seriously be considered for adjustment in nearly all data stage ETL projects. The adjustment must be based on the amount of available memory, the volume of work load that is sequential file intensive, and the environment you’re working in. Some experiential adjustment may be required, but I have provided a few recommendations below.

Environment Variable Properties

Category NameTypeParameter NamePromptSizeDefault Value
Parallel > Operator SpecificStringAPT_FILE_EXPORT_BUFFER_SIZESequential write buffer sizeAdjustable in 8 KB units.  Recommended values for Dev: 2048; Test & Prod: 4096.128
Parallel > Operator SpecificStringAPT_FILE_IMPORT_BUFFER_SIZESequential read buffer sizeAdjustable in 8 KB units.  Recommended values for Dev: 2048; Test & Prod: 4096.128

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