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

From Pietro Pugni
Subject Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL
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Msg-id F3A49DF3-A91B-4980-99AA-8381882B0C94@gmail.com
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In response to Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL  (Wei Shan <weishan.ang@gmail.com>)
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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@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 <aidan@highrise.ca> wrote:
On Wed, Apr 1, 2015 at 9:56 AM, Pietro Pugni <pietro.pugni@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

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