[Postgres-xc-general] Question about executing queries against Datanode.

[Tomonari K. <kat...@po...>]

Hi,

When I use Postgres-XC 1.0.0 and execute a query against datanode,
I get below WARNING messages.
------------------------------------
Do not have a GTM snapshot available
------------------------------------

When I use Postgres-XC 1.0.1 and execute a query against datanode,
I don't any WARNING messages.

I think it's because of below changes.
---
ref.)Release Note
- Fix snapshot management on slave nodes and on Datanodes accessed
directly by applications (Michael Paquier)

A slave node session acquires its snapshot directly from WAL like
PostgreSQL does. Also, a Datanode is now able to get a global snapshot
directly from GTM, avoiding WARNING messages that a snapshot is not
available.

Queries interacting with remote nodes running on slave nodes are blocked.
Such queries need a global snapshot and a new transaction ID, but
sessions on
slave nodes cannot acquire that.
---

I've understood that it's safe to execute against datanode on higher
version of Postgres-XC 1.0.1.
Is this right?

---------
Tomonari Katsumata