Dmitry Yemanov wrote:

> Our execution tree doesn't have any useless grammatical nodes, they're
> eliminated during the SQL->BLR compilation. The only node that doesn't
> perform any useful work itself is nod_list which acts as a container for
> other nodes.

There is an exception. It's not useless, but is not essential: nod_src.
It runs for each line, if in a loop.

It may not appear very cost because the cost of each SQL statement is
generally much larger, but can be optimized (putting the line number
directly in each node when compiling, for example).


Adriano