Restart reader
You may want to check the size of the of shared pool and then increase accordingly.
Also check for out of sync's as when reader encounters this error "11009 - GetKeyValues failed: ORA-04031" on that rowid it will not process that record. The reader log (*ord* log) has the information about the row it had this error on. So there is a chance that these rows will be out of sync on the target.
