Parallel replication has been around for a few years now but is still not that commonly used. I had a customer where the master had a very large write workload. The slave could not keep up so I recommended to use parallel slave threads. But how can I measure if it really helps and is working?
At my customer the
was 0. But how big should I increase it, maybe to 1? Maybe to 10? There is a blog post about how can we see how many threads are actually used, which is a great help.
We changed the following variables on the slave:
slave_parallel_type = LOGICAL_CLOCK; slave_parallel_workers = 40; slave_preserve_commit_order = ON;
40 threads sounds a lot, right? Of course, this is workload specific: if the transactions are independent it might …[Read more]