The solution is
dbms_redefinition package. Basically redefition will move, online, to a new table (called interim table), then move all dependent objets like indexes and last exchange the interim table with the original one.
What you have to do is:
- Create the interim table withe correct column definition
- Run redefinition
- Drop the old table
dbms_redefinition in the following way:
-- DETERMINE IF THE ORIGINAL TABLE CAN BE REDEFINED ONLINE
-- BEGIN THE REDEFINITION
UNAME => 'SCHEMA',
ORIG_TABLE => 'YOURTABLE',
INT_TABLE => 'INTERIM_YOURTABLE'
OPTIONS_FLAG => DBMS_REDEFINITION.CONS_USE_ROWID);
-- IF THE TABLE HAD DEPENDENCIES (INDEXES ... CONSTRAINTS ... TRIGGERS)
-- THIS WOULD BE THE POINT AT WHICH THEY WOULD HAVE BEEN COPIED
error_count pls_integer := 0;
DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS('SCHEMA', 'YOURTABLE', 'INTERIM_YOURTABLE',
dbms_redefinition.cons_orig_params, TRUE, TRUE, TRUE, FALSE, error_count);
DBMS_OUTPUT.PUT_LINE('errors := ' || TO_CHAR(error_count));
-- FINISH THE REDEFINITION
If you run redefinition with SYSTEM user there is no problem. If you want to execute it with a less privileged user you have to trick some privileges in order to get it working. Privileges required are:
- Execute privilege to DBMS_REDEFINITION
- Create any table
- Alter any table
- Drop any table
- Lock any table
- Select any table
Tables with the following characteristics cannot be redefined online:
- [9.0.1]Tables with no primary keys
- Tables that have materialized view logs defined on them
- [9i] Tables that are materialized view container tables and AQ tables
- [10g] Tables that are replicated in an n-way master configuration can be redefined, but horizontal subsetting (subset of rows in the table), vertical subsetting (subset of columns in the table), and column transformations are not allowed.
- The overflow table of an IOT table
- Tables with fine-grained access control (row-level security)
- Tables with BFILE columns
- Tables with LONG columns can be redefined online, but those columns must be converted to CLOBS. Also, LONG RAW columns must be converted to BLOBS. Tables with LOB columns are acceptable.
- Tables in the SYS and SYSTEM schema
- Temporary tables
- A subset of rows in the table
- Only simple deterministic expressions, sequences, and SYSDATE can be used when mapping the columns in the interim table to those of the original table. For example, subqueries are not allowed.
- If new columns are being added with no column mappings, then they must not be declared NOT NULL until the redefinition is complete.
- There cannot be any referential constraints between the table being redefined and the interim table.
- Table redefinition cannot be done NOLOGGING.
- [10g] For materialized view logs and queue tables, online redefinition is restricted to changes in physical properties.
- You cannot convert a nested table to a VARRAY.