Hi Wei Shan, Thank you for your response. Query B was run after initializing the DB ex-novo doing VACUUM ANALYZE before and after creating and clustering indexes. By the way, these results are consistent through time and are reproducible, so it’s not a metter of statistic collector (I guess). Your observation is the same done at dba.stackexchange.com and this make me think that the built-in Postgres of OS X Server is truly optimized.
Best regards, Pietro PS on the other response I reported both postgresql.conf Il giorno 01/apr/2015, alle ore 16:44, Wei Shan <weishan....@gmail.com> ha scritto: > Just looking at the 2 B_2 queries, I'm curious as to why is the execution > plan different between the 2 machines. Is the optimiser stats updated on both > databases? > > Regards, > Wei Shan > > On 1 April 2015 at 22:32, Aidan Van Dyk <ai...@highrise.ca> wrote: > On Wed, Apr 1, 2015 at 9:56 AM, Pietro Pugni <pietro.pu...@gmail.com> wrote: > > Now let’s propose some query profiling times. > > B type set are transactions, so it's impossible for me to post EXPLAIN > ANALYZE results. I've extracted two querys from a single transactions and > executed the twos on both system. Here are the results: > > T420 > > Query B_1 [55999.649 ms + 0.639 ms] http://explain.depesz.com/s/LbM > > Query B_2 [95664.832 ms + 0.523 ms] http://explain.depesz.com/s/v06 > > MacMini > > Query B_1 [56315.614 ms] http://explain.depesz.com/s/uZTx > > Query B_2 [44890.813 ms] http://explain.depesz.com/s/y7Dk > > > Looking at the 2 B_2 queries (since they are so drastically different), the > in-memory quicksorts stand out on the Dell as being *drastically* slower than > the disk-based sorts on your mac-mini.... > > > > > -- > Regards, > Ang Wei Shan
