[Postgres-xc-developers] Understanding how coordinator collects data from datanodes

[Manikandan S. <ma...@vt...>]

Hi,

Am trying to understand how the coordinator node collects query results
from the datanodes. I see the method handle_response()
in ../backend/pgxc/pool/execRemote.c is called for every connection
handle. In an infinite for loop, it collects messages from the data
nodes and combines the results. I am confused between the two case
statements 'D' and 'd'. What is the difference between these two cases?
What exactly is the difference between the methods 'HandleDataRow' and
'HandleCopyDataRow' and can you give an example when each of these
methods are invoked? Please help. This will help in my research work.

Thanks
Mani