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Oracle Troubleshooting

ORA-01466: unable to read data - table definition has changed


The error (possibly during an export):

ORA-01466: unable to read data - table definition has changed


Oracle has detected a problem when trying to read the database table (or index). The creation timestamp of the table (or index) is in the future.

Possible remedies:

  • According to Oracle this could be caused by a long running snapshot. Try committing or rolling-back all outstanding transactions and try again.
  • The system time has been changed. Oracle suggest exporting the affected tables, dropping the tables and importing them.
  • If this error is encountered when trying to export tables then try exporting the tables without the flag 'consistent=Y'.

This page represents one page of many pages of notes I made whilst working with Oracle 7 through to 10i. I now no longer work with Oracle databases, but hope that these notes will continue to be of benefit to others.

About the author: is a dedicated software developer and webmaster. For his day job he develops websites and desktop applications as well as providing IT services. He moonlights as a technical author and consultant.