(2011/12/13 18:57), Albe Laurenz wrote:
> Maybe I'm missing something, but if pushdown worked as follows:
>
> - Push down only system functions and operators on system types.
> - Only push down what is guaranteed to work.
Oh, I didn't care whether system data types. Indeed user defined types
would not be safe to push down.
> then the only things we would miss out on are encoding- or
> collation-sensitive string operations.
>
> Is that loss so big that it warrants a lot of effort?
It depends on the definition of "collation-sensitive". If we define it
as "all operations which might handle any collation-sensitive element",
all functions/operators which take any of character data types (text,
varchar, bpchar, sql_identifier, etc.) are unable to be pushed down.
Regards,
--
Shigeru Hanada