https://www.oraclescripts.com/tags/dbms_redefinition/Recent content in DBMS_REDEFINITION on Oracle ScriptsHugo -- gohugo.ioenOracleScripts.comFri, 18 Sep 2026 00:00:00 +0000https://www.oraclescripts.com/post/redefine-table-online-dbms-redefinition-no-dml-blocking/Fri, 18 Sep 2026 00:00:00 +0000https://www.oraclescripts.com/post/redefine-table-online-dbms-redefinition-no-dml-blocking/ <h2 id="redefine-a-table-online-with-dbms_redefinition-no-dml-blocking">Redefine a Table Online with DBMS_REDEFINITION, No DML Blocking</h2> <h2 id="purpose">Purpose</h2> <p>A DBA moving a table to a new tablespace, adding compression, or rebuilding a badly fragmented segment has one hard requirement: users can't lose access to that table while the change is happening. For decades the available tools — <code>CREATE TABLE AS SELECT</code> plus a rename, or a plain <code>ALTER TABLE MOVE</code> — all lock the table for at least part of the operation, even if only briefly. <strong><a href="https://docs.oracle.com/en/database/oracle/oracle-database/19/arpls/DBMS_REDEFINITION.html">DBMS_REDEFINITION</a></strong> restructures a table while it stays fully readable and writable the entire time.</p>