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 for more info.