On Mon, Jun 1, 2009 at 11:11 PM, Kristian Nielsen <[email protected]> wrote: > [email protected] writes: > >> Benchmarking did not show any significant benefit of having parallel >> applying. >> Reason is that RBR applying is so fast compared to processing >> of SQL queries that applying queue did not build up. It turned out that >> several applier threads were useful only when transaction length was ~200 SQL >> statements. > > Sounds like you are testing a CPU bound load with all data in memory? > > If you test against a disk-bound load with data spread out over multiple disk > drives, you would probably see a much higher benefit. A single-threaded > replication thread is not able to utilise the possibility to have multiple > outstanding I/O running in parallel on multiple disks.
And given the urge to economize, we want to put as much load as possible on a slave without creating significant replication delay. So this can be a really valuable feature. I have no problem generating load that will make the slave get behind on replication -- just consolidate more clients on a smaller number of servers. -- Mark Callaghan [email protected] _______________________________________________ Mailing list: https://launchpad.net/~drizzle-discuss Post to : [email protected] Unsubscribe : https://launchpad.net/~drizzle-discuss More help : https://help.launchpad.net/ListHelp
