On Wed, 2006-03-22 at 16:36 -0500, Merlin Moncure wrote: > Chis Browne wrote: > > PostgreSQL is likely to be way slower if you submit streams of little > > queries, each an independent transaction... > > When I get around to it I plan on debunking this ;). I recently did > extensive internal benchmarking of mysql 5.0 vs. postgresql 8.1 and > it's victories across the board with only a couple of exceptions, and > I have benchmarks to prove it. Im summary: > > 1. mysql is faster when it's query cache hit ratio is high > 2. mysql opens connections much faster than pg, which is why we use pgpool > 3. mysql sometimes wins where mvcc delete + insert can be kind of a > pain (*much* rarer than commonly thought) > > While 'out of the box' postgresql is slower at select a,b,c from t > where k type queries wrt mysql, the performance advantage is > completely negated if you run those queries via prepared statements. > > In postgresql, queries executed over the parameterized/prepared C api > are particularly fast...as much as a 70% speed reduction over vanilla > PQexec. Now, the lower level API and prepared statements are not > available for all applications, but when used they provide extremely > low-latency access. > > Also, > 1. pg can read off large result sets (50k records +) from the cache > much faster than mysql > 2. pg has a generally better query optimizer, altough here and there > mysql scores a win > 3. many other advantages you are already quite familiar with, mvcc, etc. > > Basically, I am saying that the proverbial bread and butter queries > are not necessarily faster on mysql, just easier to get running fast, > if that makes sense. Now, I'm not trying to bash mysql (I was in > fact, quite impressed with 5.0) generally, but I really think the > claim that it is faster for a broad array of tasks is highly dubious. > pg just requires a little bit more specialized knowledge to get > running up to its level in some cases. > Out of interest, what MySQL table type did you compare against? I personally would be much more interested in such a comparison with InnoDB tables than MyISAM. -- Russ
