# 12c Online Table Redefinition Examples

I’ve been learning about online table redefinition in Oracle 12c.  Here is a zip of some test scripts I built for my own understanding: zip

I spent some time trying out DBMS_REDEFINITION on an 11.2 Exadata test system and then started messing with it on 12c in a generic Linux VM.  The 12c version of the DBMS_REDEFINITION includes a new procedure called REDEF_TABLE which lets you do in one step certain things you did with multiple calls to the package in 11.2.  This is an online table compress on 12c:

BEGIN
DBMS_REDEFINITION.REDEF_TABLE(
uname                      => user,
tname                      => 'TEST',
table_compression_type     => 'COMPRESS');
END;
/

Things that can’t be done in one step like this require calls to procedures such as CAN_REDEF_TABLE, START_REDEF_TABLE, REGISTER_DEPENDENT_OBJECT, COPY_TABLE_DEPENDENTS, and FINISH_REDEF_TABLE.  Example online12c5.sql uses all of these.  Here is a summary of each included file’s test:

online12c1.sql – compress table in one step

online12c2.sql – compress table in multiple steps and show that it creates a hidden column without a primary key

online12c3.sql – same as previous test but with primary key

online12c4.sql – copy contraints and indexes

online12c5.sql – change the columns for the non-unique index

online12c6.sql – change order and type of columns

– Bobby