On Fri, Oct 02, 2020 at 12:16:25AM +0000, tsunakawa.ta...@fujitsu.com wrote: > IIUC, walsender tries hard to send WAL as fast as possible to reduce > replication lag and transaction response time, so it doesn't try to > peek each WAL record. I think it's good.
CRC calculation would unlikely be the bottleneck here, no? I would assume that the extra lseek() calls needed to look after the record data to be more harmful. > In any case, the WAL can get corrupt during transmission, and > writing and reading on the standby. So, the standby needs to check > the WAL record CRC. Yep. However, I would worry much more about the case of cold archives. In my experience, there are higher risks to get a WAL segment corrupted because it was on disk and that this disk got corrupted. Transmission is a one-time short operation. Cold archives could stay on disk for weeks before getting reused in WAL replay. -- Michael
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