On Sun, Feb 13, 2011 at 12:04:20AM -0500, Robert Haas wrote: > On Sat, Feb 12, 2011 at 10:45 AM, Noah Misch <n...@leadboat.com> wrote: > > That said, I've tried both constructions, and I marginally prefer the end > > result > > with AlteredTableInfo.verify. ?I've inlined ATColumnChangeRequiresRewrite > > into > > ATPrepAlterColumnType; it would need to either pass back two bools or take > > an > > AlteredTableInfo arg to mutate, so this seemed cleaner. > > I think I like the idea of passing it the AlteredTableInfo.
Okay. > > I've omitted the > > assertion that my previous version added to ATRewriteTable; it was helpful > > for > > other scan-only type changes, but it's excessive for domains alone. > > ?Otherwise, > > the differences are cosmetic. > > So in the case of a constrained domain, it looks like we're going to > evaluate the changed columns, but if no error is thrown, we're going > to assume they match the original ones and throw out the data? Correct. We can see that a RelabelType changes no values by inspecting ExecEvalRelabelType. Likewise, by inspecting ExecEvalCoerceToDomain, we can know that a CoerceToDomain node may introduce errors but never modified values. > Yikes. > I didn't like that Assert much, but maybe we need it, because this is > scary. Can you elaborate on the fear-inducing aspect? I don't mind re-adding the Assert, but it seems that some positive understanding of the assumption's validity is in order. nm -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
