On 2024-Nov-25, Robert Haas wrote: > In a simple implementation of ALTER TABLE this would be true, but I > don't see why it should need to be true in ours. It should be possible > to notice that there's an existing NOT NULL constraint and use that as > evidence that the new one can be added without needing to revalidate > the table contents. ALTER TABLE does similar things already. For > instance, TryReuseIndex() can attempt to attach an existing index file > to a new index definition without rebuilding it; TryReuseForeignKey > can attempt to re-add a foreign key constraint without needing to > revalidate it. But even more to the point, ATAddCheckNNConstraint and > MergeWithExistingConstraint know about merging a newly-added > constraint with a preexisting one without needing to revalidate the > table.
I think you're explaining why we need this patch, which seems a bit useless in the thread where this patch was posted. -- Álvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/
