It is a mandatory privilege for when you export from one user schema and import it into another schema. You cannot do this. You MUST create another temporary table if you wish to maintain any data, drop the original table, create it with the new column name, and then copy the data back from the temporary temp. I mean a regular table that exists only for the exercise of renaming columns. The other alternative is to use the third-party tool such as Platinum's TSReorg.
Row chaining is when one record is stored in two or more physical data blocks.
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