Re: Optimization of vacuum for logical replication

On 21.08.2019 12:34, Bernd Helmle wrote:
> Am Mittwoch, den 21.08.2019, 12:20 +0300 schrieb Konstantin Knizhnik:
>> I wonder if we can check that
>>
>> 1. wal_revel is "logical"
>> 2. There are no physical replication slots
>> 3. WAL archiving is disables
> Not sure i get that correctly, i can still have a physical standby
> without replication slots connected to such an instance. How would your
> idea handle this situation?

Yes, it is possible to have physical replica withotu replication slot.
But it is not safe, because there is always a risk that lag between 
master and replica becomes larger than size of WAL kept at master.
Also I can't believe that  DBA which explicitly sets wal_level is set to 
logical will use streaming replication without associated replication slot.

And certainly it is possible to add GUC which controls such optimization.

-- 

Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company