Re: Why does exprCollation reject List node?

On Fri, Mar 16, 2012 at 10:17 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Shigeru HANADA <shigeru.hanada@gmail.com> writes:
>> During writing pgsql_fdw codes, I noticed that exprCollation rejects
>> non-Expr nodes with error "unrecognized node type: %d".  Is this
>> intentional behavior, or can it return InvalidOid for unrecognized nodes
>> like exprInputCollation?
>
> Doesn't seem to me that asking for the collation of a list is very
> sensible, so I don't see a problem with that.

Oh, I've used the function wrongly.  It returns the collation of the
result of the expression, so passing a list doesn't make any sense.
The comment of expression_tree_walker clearly says that it can handle
List as well, so handling List in foreign_expr_walker by calilng
itself recursively for each element in the list seems necessary.

Regards,
--
Shigeru Hanada