2014-06-13 17:32 GMT+02:00 Tom Lane <t...@sss.pgh.pa.us>: > David G Johnston <david.g.johns...@gmail.com> writes: > > Tom Lane-2 wrote > >> At the very least I think we should stay away from this syntax until > >> the SQL committee understand it better than they evidently do today. > >> I don't want to implement it and then get caught by a future > >> clarification that resolves the issue differently than we did. > > > Its not quite as unclear as you make it out to be: > > Yes it is. > > > Though I suppose someone might want to do the following: > > random_1, random_2, random_3 float := random(1234); > > The decision to copy, not re-execute, is safer to use as the behavior and > > force explicitness in the re-execute situation. > > I would agree with that argument, if we both sat on the SQL committee and > were discussing how to resolve the ambiguity. We don't, and we have no > good way to predict what they'll do (when and if they do anything :-(). > > The problem I've got is that a literal reading of the spec seems to > suggest multiple evaluation, since "DV" appears to refer to the syntactic > construct representing the initializer, not its evaluated value. It's > hard to argue that the spec isn't telling us to do this: > > SET random_1 = random(1234); > SET random_2 = random(1234); > SET random_3 = random(1234); > > That's not the reading I want, and it's not the reading you want either, > but there is nothing in the existing text that justifies single > evaluation. So I think we'd be well advised to sit on our hands until > the committee clarifies that. It's not like there is some urgent reason > to have this feature. >
I don't think so this feature is 100% necessary, but a few users requested some more compressed form of variable declarations. we can allow multi variable declaration without initial value specification so "a,b,c text" can be valid, and "a,b,c text := 'hello'" not It is just step to users who knows this feature from others languages. Regards Pavel > > regards, tom lane > > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers >
