[Postgres-xl-developers] about coordinator

Mason Sharp msharp at translattice.com
Wed Aug 20 15:44:16 PDT 2014

On Mon, Aug 18, 2014 at 9:36 PM, bryain <pgdevuser at 163.com> wrote:

> Hi,All
> I am interested in coordinator module. I will read the sourcecode about
> coordinator,who can tell me how I can begin to read.Have any documents in
> this field? thanks!
I am not sure that there is a detailed doc for that. You can search
slideshare.net for some presentations that discuss the architecture. Also,
the postgres-xl.org website may have some info.

I can provide some info.

Both the coordinator and datanode use the same binary, but they run in
different modes, either as a coordinator, or a datanode.  The coordinator
just has a copy of the catalog info, but no user data. The coordinator
maintains session state, and parses and plans queries and sends subplans
down to the datanodes. It gets these connections from a pooler process that
it is forked off of the main process. Also, the coordinator interacts with
GTM to obtain transaction identifiers (XIDs) and snapshots.

I hope that helps.

Mason Sharp

TransLattice - http://www.translattice.com
Distributed and Clustered Database Solutions
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