Re: Thinking about EXPLAIN ALTER TABLE

>>> We were just busy shooting down a different suggestion of
>>> behavior-changing GUCs.  A GUC that turns all ALTERs into no-ops
>>> sure seems like a foot-gun to me.
>> Yeah, I like EXPLAIN better.
> +1 for EXPLAIN

IMVHO, and for "symmetry" with existing mechanisms:

* EXPLAIN ALTER TABLE    ==> "DDL dry run", but tell me what would be 
done (similar to what EXPLAIN SELECT does)

* EXPLAIN PERFORM ALTER TABLE    (EXPLAIN EXEC?)    would explain + do

     ...and bonus points for explaining each step just before it is 
performed. This way, It'd be easy for users to verify that a particular 
step (i.e. table rewrite) is the one taking æons to run or hammering the 
storage.

     Of course, regular "ALTER TABLE" stays as it is.


Just my .02€ :)

I'm not familiar with this part of the code and clearly can't devote 
enough time to do it in the near future, but count on me to test it if 
accepted.


Thanks,

     Jose