Heikki Linnakangas napsal(a):
It the new attribute is added to the end, the old tuples will be
compatible as is. If there's no null bitmap (or it's shorter than
expectd), attributes missing from a tuple are implicitly NULL. That's
how we support ALTER TABLE ADD COLUMN without rewriting all the data.
Yeah, but better is to put int column before chunk data. It save space
(alignment). I prefer to put attno as a third column.
Zdenek
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