Oracle dbms_redefinition

Oracle Tables and Indexes may be rebuild online using dbms_redefinition utility package. Exceptions are those tables on which Materialized views are defined.

While making drastic changes to the table structure using the CAN_REDEF_TABLE may be useful to findout whether online rebuilding is possible or not.

The following is an useful article

Oracle dbms_redefinition

DB Link creation format

Just for reference, even if there is no tns_names entry, we can use the complete connect string.

create database link MY_DBLINK connect to schema_user identified by pswd using '(DESCRIPTION =(ADDRESS_LIST =(ADDRESS =(COMMUNITY = tcp.world)(PROTOCOL = TCP)(Host = myserver.unix.myorg.org)(Port = 1521)))(CONNECT_DATA = (SID = MYDB_SID)))'


With tns entry: create database link MY_DBLINK connect to schema_user identified by pswd using 'TNS_CONNECT_ENTRY'