Oracle 12.1.0.2 brings a great new functionality: you can create thin clones – that is, not copying the source files, just pointers – on ext4 filesystem, the current default on Red Hat Linux 6.<\/p>\n
Requirements for example below:
\n– Oracle 12.1.0.2
\n– Data files are on ext4 filesystem (or other supporting sparse files)
\n– Source PDB on read only mode<\/p>\n
It is very simple to set up:<\/p>\n
\r\nSQL> alter system set clonedb=TRUE scope=spfile;\r\nSQL> shutdown immediate\r\nSQL> startup\r\n\r\nSQL> show parameter clonedb\r\nNAME TYPE VALUE\r\n------------------------------------ ----------- ------------------------------\r\nclonedb boolean TRUE\r\n<\/pre>\nI will create a clone of the PDB2 database. <\/p>\n
\r\nSQL> select name,con_id,open_mode,SNAPSHOT_PARENT_CON_ID from v$pdbs;\r\n\r\nNAME CON_ID OPEN_MODE SNAPSHOT_PARENT_CON_ID\r\n------------------------------ ---------- ---------- ----------------------\r\nPDB$SEED 2 READ ONLY 0\r\nPDB1 3 MOUNTED 0\r\nPDB2 4 READ ONLY 0\r\n<\/pre>\nFor this I need first to create the target directory for the datafiles.<\/p>\n
\r\nSQL> ! mkdir -p \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1\r\n<\/pre>\nThen I can do the clone using the ‘snapshot copy’ clause. It took 9 seconds.<\/p>\n
\r\nSQL> create pluggable database PDB2_C1 from PDB2 snapshot copy file_name_convert=('\/u01\/app\/oracle\/oradata\/NONRAC\/PDB2','\/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1');\r\nPluggable database created.\r\n\r\nElapsed: 00:00:09.35\r\n<\/pre>\nNote that the new PDB remains in MOUNT state and without showing a connection to its parent. I find unfortunate the lack of that information. <\/p>\n
\r\nSQL> select name,con_id,open_mode,SNAPSHOT_PARENT_CON_ID from v$pdbs;\r\n\r\nNAME CON_ID OPEN_MODE SNAPSHOT_PARENT_CON_ID\r\n------------------------------ ---------- ---------- ----------------------\r\nPDB$SEED 2 READ ONLY 0\r\nPDB1 3 MOUNTED 0\r\nPDB2 4 READ ONLY 0\r\nPDB2_C1 5 MOUNTED 0\r\n<\/pre>\nAfter we open the clone in READ WRITE mode, then we can see the relationship with the parent. <\/p>\n
\r\nSQL> alter pluggable database PDB2_C1 open read write;\r\nPluggable database altered.\r\nElapsed: 00:00:02.12\r\n\r\nSQL> select name,con_id,open_mode,SNAPSHOT_PARENT_CON_ID from v$pdbs;\r\n\r\nNAME CON_ID OPEN_MODE SNAPSHOT_PARENT_CON_ID\r\n------------------------------ ---------- ---------- ----------------------\r\nPDB$SEED 2 READ ONLY 0\r\nPDB1 3 MOUNTED 0\r\nPDB2 4 READ ONLY 0\r\nPDB2_C1 5 READ WRITE 4\r\n<\/pre>\nAnd below we verify that the clone uses 4MB instead of 800MB of the source database. <\/p>\n
\r\nSQL> ! du -m \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2\/*\r\n6 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2\/PDB2_users01.dbf\r\n586 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2\/sysaux01.dbf\r\n261 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2\/system01.dbf\r\n1 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2\/temp01.dbf\r\n\r\nSQL> ! du -m \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1\/*\r\n1 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1\/PDB2_users01.dbf\r\n1 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1\/sysaux01.dbf\r\n1 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1\/system01.dbf\r\n1 \/u01\/app\/oracle\/oradata\/NONRAC\/PDB2_CLONE1\/temp01.dbf\r\n<\/pre>\nWe can also clone non-CDB databases with some more steps, as explained at:
\nhttps:\/\/dbamarco.wordpress.com\/2015\/03\/09\/small-change-big-difference\/<\/a><\/p>\n