Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL

[Pietro Pugni <pietro.pugni@xxxxxxxxx>]

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.ang@xxxxxxxxx> 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 <aidan@xxxxxxxxxxx> wrote:

On Wed, Apr 1, 2015 at 9:56 AM, Pietro Pugni <pietro.pugni@xxxxxxxxx> 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....

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Regards,
Ang Wei Shan