Alvaro Herrera <> writes:
> Andres Freund wrote:
>> I think the best way to really cleanup a table is to use something like:
>> ALTER TABLE rew ALTER COLUMN data TYPE text USING (data);
>> where text is the previous type of the column. That should trigger a
>> full table rewrite, without any finesse about tracking ctid chains.

> Isn't this what VACUUM FULL does?

AFAIR, both VACUUM FULL and CLUSTER will attempt to preserve update
chains, and thus will probably get confused by this bug (though I've
not looked into exactly what will happen).  I'm not real sure that ALTER
TABLE is any better --- doesn't all that stuff go through rewriteheap.c

                        regards, tom lane

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