Re: Incremental sort for access method with ordered scan support (amcanorderbyop)

Thanks for feedback

> 2. You can use list_copy_head(root->query_pathkeys,
> list_length(orderbyclauses)); instead of:
>
> + useful_pathkeys = list_truncate(list_copy(root->query_pathkeys),
> +     list_length(orderbyclauses));

This code will crash if query_pathkeys is NIL. I need either modify
list_copy_head (v3.1) or add checks before call (v3.2).

I don't know if it's a good idea to modify list_copy_head. It will add
additional overhead to every call.

-- 
Best regards
Miroslav