Make T_CoalesceExpr executable on a foreign server - Mailing list pgsql-hackers

Hello.
Currently, T_CoalesceExpr is not executable on the foreign server.
This functionality could be useful and the fix appears to be 
straightforward.

The proposed modification extends foreign_expr_walker to handle
T_CoalesceExpr node, deparseCoalesceExpr is added to
deparseExpr. A test case for COALESCE is also included.

Regards,
Pavel