Hi Andres, On Fri, 9 Feb 2024 at 22:33, Andres Freund <and...@anarazel.de> wrote:
> On 2024-01-19 23:04:50 +0330, Majid Garoosi wrote: > > Following is the description which is also written in the commit message: > > MAX_SEND_SIZE parameter was used in WALSender to limit maximum size of > > a WAL data packet sent to a WALReceiver during replication. Although > > its default value (128kB) was a reasonable value, it was written in > > 2010. Since the hardwares have changed a lot since then, a PostgreSQL > > user might need to customize this value. > > For example, if a database's disk has a high bandwidth and a high > > latency at the same time, it makes more sense to read bigger chunks of > > data from disk in each iteration. One example of such disks is a remote > > disk. (e.g. an RBD volume) > > The way we read the WAL data is perfectly prefetchable by the the OS, so I > wouldn't really expect gains here. Have you actually been able to see a > performance benefit by increasing MAX_SEND_SIZE? > Yes, I have seen a huge performance jump. Take a look at here <https://www.postgresql.org/message-id/CAFWczPvi_5FWH%2BJTqkWbi%2Bw83hy%3DMYg%3D2hKK0%3DJZBe9%3DhTpE4w%40mail.gmail.com> for more info. Best Majid
