Programmer Guide : Transaction Log Reader : Partitioning and filtering log records
  
Partitioning and filtering log records
By default, all the log records generated by any application are returned. If you only want to access the log records for a subset of the database, you can specify log reader partitions. A Log Reader partition is a named collection of tables. The partitions may overlap. Information about the partitions is stored in SYS_FEDT_DB_PARTITION and SYS_FEDT_TABLE_PARTITION system tables.
See also
Creating and deleting partitions
Using partition filters
Transaction Log Reader