
Which execution route did the last collect() take?
garry_last_route.RdA diagnostics helper. The distributed collect() picks its execution
route automatically, and this reports the route the last call took,
so pipelines can log it or assert a plan has not changed route.
The values are:
Value
"composite_direct", "gd_reduce", "scheduler" or
"single"; NULL before any collect() in the session.