AWS DMS ( Data Migration Service ) task has been running for many hours, then failed with error “Table error” for Load State.
1)Check target database, 99% records have been migrated from Oracle source database to PostgreSQL RDS.
2)Check task log with bellow error:
00:04:00 2018-10-01T00:04:00 [SOURCE_UNLOAD ]E: ORA-01555: snapshot too old: rollback segment number 918 with name "_SYSSMU918_239767949$" too small  (oracle_endpoint_unload.c:226)
Add more space to UNDO tablespace, and/or increase the value of parameter “undo_retention” for source Oracle database.