Refreshable Clone PDBs

定期刷新的只读数据库。

CREATE PLUGGABLE DATABASE pdb1_ref_cln FROM pdb1@pdb1_link REFRESH MODE EVERY 60 MINUTES;

快照克隆：

CREATE PLUGGABLE DATABASE pdb1_copy FROM pdb1 
  USING SNAPSHOT pdb1_wed_4_1201;

自动快照：

SELECT SNAPSHOT_MODE "S_MODE", SNAPSHOT_INTERVAL/60 "SNAP_INT_HRS" 
FROM   DBA_PDBS;

ALTER PLUGGABLE DATABASE SNAPSHOT MODE EVERY 24 HOURS;