$ time mysql < employees.sql real 0m27.997s user 0m1.394s sys 0m1.046s
$ time mysql < employees.sql real 1m24.277s user 0m3.842s sys 0m6.270s
Semi-synchronous replication was three times slower than regular replication. The test was taken using one master in one host and one slave in two more hosts. The measurements were the same if I had only one or both slaves enabled. Using row-based replication instead of statement-based did not make any substantial impact. Now my question is: who would be prepared to accept such a performance impact for the sake of more data safety? Data is important, but response time to customers is also important. Your mileage may vary. I know many customers who would think twice before accepting this onerous trade off. I am curious to know what experience others have had with this feature, and how much performance they are willing to sacrifice for safety.