An application can require a DB to be available for quick updates and slow queries would interfere with this. A solution is to replicate the DB for queries.
Run tutorial for more info:
The rlog arg is the folder that holds info from the src DB required to replicate the DB in the snk DB.
report db rep status
stops db (either src or snk) use of rlog folder
initializes rlog folder with copy of db and sets up for logging new change ops
db ops first update as required from rlog file updates db from folder