DBMS_LOGSTDBY.INSTANTIATE and Job already exists error
When you run DBMS_LOGSTDBY.INSTANTIATE_TABLE, it actually create a table SYS_IMPORT_TABLE_nn, (I run as sys. If you run as another user, the table name might be different.).
After the job run successfully, Oracle does not delete the table.
Seems Oracle only allowing 100 such tables (i.e., nn between 0 and 99). If you run the procedure more than 100 times, you will receive an error ORA-31634: job already exists.
Quite a silly omission from Oracle.
You can use : select * from dba_datapump_jobs order by job_name to verify.
The solution is quite simple, just drop the table SYS_IMPORT_TABLE_nn. Before dropping it, make sure the job associated with the table is not running. The status is “NOt Running” in dba_datapump_jobs.