Re: PG12: Any drawback of increasing wal_keep_segments

On 29 Mar 2022, at 17:17, Stephen Frost wrote:

> Greetings,
>
> * Alvaro Herrera (alvherre(at)alvh(dot)no-ip(dot)org) wrote:
>> On 2022-Mar-22, Shukla, Pranjal wrote:
>>> Are there any disadvantages of increasing the
>>> “wal_keep_segments” to a
>>> higher number say, 500? Will it have any impact on performance of
>>> streaming replication, on primary or secondary servers?
>>
>> No. It just means WAL will occupy more disk space. I've seen people
>> go
>> even as high as 5000 with no issues.
>
> Yeah, though it makes the primary into essentially a WAL repository
> and,
> really, you'd be better off having a dedicated repo that replicas can
> pull from instead. Consider that a replica might fall way behind and
> then demand the primary send 5000 WAL segments to it. The primary
> then
> has to go pull that 80GB of data from disk and send it across the
> network. As to if that's an issue or not depends on the IOPS and
> bandwidth available, of course, but it's not free.
>
> Thanks,
>
> Stephen

Hello Stephen,

How do you see a setup with a ‘a dedicated repo that replicas can pull
from’ ?

Thanks in advance for the clarification.

Marc