Informatica parameter file is a text file which contains 1) Parameter values 2) Variable values for mapping, session and workflows. Broadly it keeps the properties of workflows, sessions and mappings.here few usage of informatica parameter file which can provide some insight of its need.
1) Develop environment independent code.
:: Your project is in development phase where you are supposed to write code for some client, but will that informatica code will run at your client ETL server also?
:: One can parameterize all the attributes which are environment specific, Deploy the code and just change the parameter file and your informatica code will work fine at client ETL server.
2 ) Control data processing without changing the code in PROD environment.
::Your informatica code process millions of transaction per day and you want to control it from outside that means Sunday to Thursday you want to process less then 5 million records and on weekday you want to process even less then 1 million records just to offload some work from informatica server caused by additional weekend data processing.
:: Write a source qualifier query like this (Where rownum < $$ROWNUM), and you can control it.
3 ) Easy deployment to production server.
:: your informatica code needs to deployed on production server and as always you will not have access to production server, So to deploy the code properly we need to provide instructions to deployment team to perform cosmetic changes in informatica code. Majority of the cases we are not so lucky that deployment team can perform those tasks without any support.
:: To overcome this problem one can parameterize all the stuffs which are subject to change on a different server.
4 ) Provide Flexibility to run sessions for different files and databases:
With the help of sessions parameter (File and database connection parameter) we can read from different files and write to different database tables just with one session. What you have to do is that you have to provide different parameter files to pmcmd command,
First time session run – ParamFile1 which will read from File1 and will write DatabaseTable1.
Second Time session run – ParamFile2 which will read from File2 and will write to DatabaseTable2.
Go to => Sessions – Properties tab – parameter file attribute