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]