On Thu, Mar 10, 2011 at 05:16:52PM -0500, Tom Lane wrote: > On the other hand ... one thing that's been bothering me is that > select_common_collation assumes that "explicit" collation derivation > doesn't bubble up in the tree, ie a COLLATE is only a forcing function > for the immediate parent expression node. It's not at all clear to me > that that's a correct reading of the spec. If it's not, the only way > we could make it work correctly in the current design is to keep > *two* additional fields, both the collation OID and an explicit/implicit > derivation flag. Which would be well past the level of annoying. > But in a post-pass implementation it would be no great trouble to do > either one, and we'd not be looking at a forced initdb to change our > minds either.
I beleive the current interpretation, that is the COLLATE only applies to levels above, is the correct interpretation. COLLATE binds tightly, so A op B COLLATE C parses as A op (B COLLATE C) which is why it works. It's actually the only way that makes sense, otherwise it becomes completely impossible to specify different collations for a function and its return value. For example in your example with a view: CREATE VIEW foo AS func(x COLLATE A) COLLATE B; B is the collation for the output column, A is the collation for the function. Have a nice day, -- Martijn van Oosterhout <klep...@svana.org> http://svana.org/kleptog/ > Patriotism is when love of your own people comes first; nationalism, > when hate for people other than your own comes first. > - Charles de Gaulle
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