On Sat, Apr 30, 2011 at 6:02 PM, Reindl Harald <h.rei...@thelounge.net>wrote:
> > Am 30.04.2011 17:45, schrieb Ferenc Kovacs: > > On Sat, Apr 30, 2011 at 5:39 PM, Rasmus Lerdorf <ras...@lerdorf.com> > wrote: > >> Do you realize why we did this in the first place? The common versions > of > >> MySQL in use out there are not very clever when it comes to the native > >> prepared statement handling. First, there is no prepared statement > cache, so > >> there is no benefit to doing them natively, but worse, when you use a > native > >> prepared statement you completely miss the query result cache. As a > result > >> emulated prepared statements are either the same speed or faster than > the > >> native ones. Changing this default would result in a performance hit for > >> most people. It should be better documented, but that is the only > problem I > >> see here. > >> > > I disable query_cache on my machines, because it can cause performance > and > > stability issues. > > > http://www.mysqlperformanceblog.com/2011/04/10/should-we-give-a-mysqlquery-cache-a-second-chance/ > > i guess you must have some really strange things in your applications > > not really. but the global mutex and the coarse invalidation makes it capable of stalling a server and it wasn't easy so spot that. at least with vanilla mysql 5.1 http://www.xaprb.com/blog/2010/09/15/making-query-cache-contention-more-obvious/ http://bugs.mysql.com/bug.php?id=56822 but this is offtopic here, I shouldn't have brought this up. Tyrael
