Redologs get created and written to, the magnitude of writing depending on the user activity on the source database. The question arises as to whether Shareplex is also responsible for generation of redologs and if so, does it impact the performance of the source database by adding to the overhead.
Shareplex is one of the users on the source database and also owns certain tables. These tables keep track of the row chaining, the object id of the replicated tables, conditions that check for rows to be replicated in horizontal partitioning, among others. All these actions do generate redologs entries. However, it is usually insignificant in comparison to the database activity. So it can be said that Shareplex's contribution to the load on the source database is miniscule.
On target database Shareplex is the only cause of activity so almost all the redolog generation is attributed to Shareplex.