Re: PG12: Any drawback of increasing wal_keep_segments
Greetings, On Thu, Mar 31, 2022 at 12:58 Marc wrote: > On 29 Mar 2022, at 17:17, Stephen Frost wrote: > > Greetings, > >- Alvaro Herrera (alvhe...@alvh.no-ip.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. > I’d suggest checking out pgbackrest. There are other options out there but that’s my favorite (probably because I also am one of the folks involved in its development, full disclosure). Thanks, Stephen >
Re: PG12: Any drawback of increasing wal_keep_segments
On 29 Mar 2022, at 17:17, Stephen Frost wrote: Greetings, * Alvaro Herrera (alvhe...@alvh.no-ip.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
Re: PG12: Any drawback of increasing wal_keep_segments
Greetings, * Alvaro Herrera (alvhe...@alvh.no-ip.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 signature.asc Description: PGP signature
Re: PG12: Any drawback of increasing wal_keep_segments
On 2022-Mar-22, Shukla, Pranjal wrote: > Team, > 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. -- Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
PG12: Any drawback of increasing wal_keep_segments
Team, 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? Thanks & Regards Pranjal Shukla
