create undo tablespace undotbs01
datafile '/u01/orcl/oradata/undotbs01.dbf' size 10M autoextend on
retention guarantee

alter tablespace undotbs01 retention guarantee
alter tablespace undotbs01 retention noguarantee

v$undostat
dba_rollback_segs
v$transaction
v$rollstat
v$rollname
dba_undo_extents

grant flashback on emp to salapati
grant flashback any table to salapati

select * from employees as of timestamp
to_timestamp('2005-01-02 08:00:00','yyyy-mm-dd hh24:mi:ss') where last_name='Alapati'

versions_startscn
versions_starttime
versions_endscn
versions_endtime
versions_operatioin
versions_xid
versions between scn minvalue and maxvalue

flashback_transaction_query（需要select any transaction系统权限）

--resumable space allocation
grant resumable to salapati
revoke resumable from salapati

alter system set resumable_timeout=7200

alter session enable resumable
alter session enable resumable name 'resumable_test'
alter session enable resumable timeout 18000
execute dbms_resumable.set_session_timeout(4349,180000)

alter session disable timeout

dba_resumable