May 2018
Intermediate to advanced
576 pages
30h 25m
English
Standby servers send feedback messages that describe the LSN of the latest transaction they have processed. Transactions committing on the master will wait until they receive feedback saying that their transaction has been processed. If there are no standbys available for sending feedback, then the transactions on the master will wait for standbys, possibly for a very long time. That is why we say that you must have at least three servers to sensibly use sync rep. It probably occurs to you that you could run with just two servers. You can, but such a configuration does not offer any transaction guarantees; it just appears to. Many people are confused on that point, but please don't listen to them!
Sync rep increases the elapsed ...