Comments - Parallel Replication

1 year, 5 months ago Steven McDowall

In your section on "Configuration variable slave-parallel-max-queued" I think you have the variables confused in the last paragraph -- at least it makes no sense to me :) I think the first uses of "slave_parallel_threads" should be "slave_parallel_max_queued" ?? Suggestion to set this variable "fairly high" to a few 100K obviously doesn't make sense .. but does for the max_queued variable ..

Here is the offending paragraph :

Usually, slave_parallel_threads should be set large enough that the SQL thread is able to read far enough ahead in the binlogs to exploit all possible parallelism. In normal operation, the slave will hopefully not be too far behind, so there will not be a need to queue much data in-memory. So slave_parallel_threads could be set fairly high (eg. few hundred kilobytes) to not limit throughtput. It should just be set low enough that the value of slave_parallel_threads * slave_parallel_max_queued will not cause the server to run out of memory.