On Tue, Jun 23, 2015 at 5:07 AM, Rui Hai Jiang <ruihaiji...@msn.com> wrote: > I'm trying to figure out how a query and its result is passed between a > coordinator and a datanode. I know there are many messages passed between > them to finish a query. > > > I did a test against the coordinator by adding a row to a table and the sql > was, insert into hg1(id, name) values(1,'tom'). > > I found a command 'P' was sent from the coordinator to a datanode and there > was a remote statement as following, > > > stmt_name=p_1_25af_f > query_string=Remote Subplan > plan_string={REMOTESTMT :commandType 3 :hasReturning false ...} > > > My questions are, > 1-does the coordinator use the remote statement to tell a datanode what to > do? If so, how is the plan string created by the coordinator and how is the > plan_string parsed by the datanode? > > 2-if there are multiple rows in the result of the query, how are the rows of > data passed from the datanode to the coordinator? Does the datanode just send > all the rows of data to the coordinator? or the coordinator get each row of > data by sending a query? > > > Thank you very much!
This is probably an appropriate question for postgres-xl-developers, but not pgsql-hackers. Those concepts do not exist in PostgreSQL, only Postgres-XC or one of its proliferating set of forks. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers