Le 05/03/2019 à 13:22, Steve Singer a écrit :
> On Tue, 5 Mar 2019, SAS wrote:
>
>> Thank you for your answer.
>>
>> I could easily drop some paths, and then lower the number of established
>> connections on some
>> nodes.
>>
>> Could you point me to what has changed between 2.1 and 2.2 branches that
>> causes this connections
>> increase? The paths were there before the upgrade.
>
> It has to do with the changes to how DDL is handled.
> In 2.1 and earlier DDL was treated as a special type of event and was
> replicated by this event in sl_event.  There were cases where DDL and data
> could be replicated in the wrong order.
>
> In 2.2 there is now a table specifically for DDL changes, like sl_log.  The
> DDL from this table is pulled in the correct order by the listener threads
> through the listener connection.
>
> DDL can be submitted on any node, and for nodes that aren't providing a
> subscription there isn't a clear cascaded network route though other nodes.
>
> For larger node setups it might be nice to have a way of designating nodes as
> 'edge only' nodes, where they can't be origin's, providers or failover
> targets and they can't accept DDL submissions.  These nodes wouldn't have to
> generate any events and so other nodes wouldn't have to listen for their
> events.  We don't currently support this though.
>
> Hope that helps.

Thank you, I now have a better understanding of the situation.


-- 
Dr Stéphane Schildknecht
Contact régional PostgreSQL pour l'Europe francophone
+33 617 11 37 42

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