Unload Periodic Group

What is the most appropriate way to extract an ADABAS file with data fields like periodic group in a text file before reloading it in an ORACLE database ?

You have to decide what the resulting RDBMS tables will look like. Typically a PE maps to a new child table with a many to one relationship to the parent table. The key of the resulting PE table is the key of the parent table plus a sequence number corresponding to the index of the PE. So your extract to text files will likely need to write out a text file for the parent record plus a text file for each PE on the parent record as each will be a distinct table in the RDBMS.

MU’s and PE’s with few fields and few (fixed) occurrences are sometimes “flattened out”. That is, given primary record with Account, Year, PE(Amount, Desc), you could map it to a table with Account, Year, Amount01, Desc01, Amount02, Desc02,…Amount12, Desc12. Assuming you have 12 PE occurrences corresponding to months of the year on a Gregorian calendar, of course.