| Thread Previous • Date Previous • Date Next • Thread Next |
On 2015-10-15 08:16, Kristian Nielsen wrote:
Monty suggested changing the behaviour also for non-parallel mode - letting Seconds_Behind_Master reflect only events actually committed, not just read from the relay log. This would introduce an incompatible behaviour for Seconds_Behind_Master, but could perhaps be done for 10.1, if desired. Doing it in stable 10.0 would be more drastic.
I agree with Monty: we should only update on commit and in both // and non-// cases.
Having yo-yo in seconds-behind-master (because of a long running transaction) should probably be considered a bug and should be fixed (non-// case).
The commit event (if we can call it as such) is the only reliable (-ish) timing synchronization point in the binlog stream, all the rest depends on execution time and session-latency. The timestamp of those non-commit events should not be trusted for delay computation.
Fixing that in 10.0 has too many implications, I think fixing in 10.1 is a good target.
If something needs to be done in 10.0, and if it is not too hard, adding a "improved_seconds_behind_master" global variables for this behavior could be done. In 10.0, the default value of this variable would be 0, in 10.1 it would be 1. If that path is chosen, I think this variable should be deprecated in 10.1 and go away in 10.2 to reduce code complexity.
Jean-François Gagné
| Thread Previous • Date Previous • Date Next • Thread Next |
