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

This is a time-based read consistency error, which may occur during flashbacking object.

For example, I was running the following statement:

SELECT text
FROM dba_views AS OF TIMESTAMP to_timestamp('8-SEP-2011 6:14:35','DD-MON-YYYY HH24:MI:SS')

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

 

Let’s check undo_retention parameter:

SQL>  SELECT value/60/60 as Hours
 2    FROM v$parameter
 3    WHERE name='undo_retention';

    HOURS
---------
3.02777777

So my retention period is 3hours…If I want to flashback object to before more than 3 hours I will get ORA-01466.

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2 Responses to ORA-01466 unable to read data – table definition has changed

  1. eme says:

    The retention period in my DB is set to default 15 minutes(900 seconds). But when trying to fetch data using AS OF SCN, it throws error “ORA-01466 unable to read data – table definition has changed” even the query executes withing 15 minutes. However the error doesn’t seem to be consistent. That is I am not able to reproduce the error. Kindly help me identify, what else could be the issue.

    • dba010 says:

      Hello,
      Thank you for reading my blog…
      This error means that during these 15 minutes you altered that table , so changed its definition, did you? Did you changed any column type of this table, or something like that?

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