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

On Wed, Apr 1, 2015 at 6:56 AM, Pietro Pugni <pietro.pugni@gmail.com> wrote:

This question was posted originally on http://dba.stackexchange.com/questions/96444/cant-get-dell-pe-t420-perc-h710-perform-better-than-a-macmini-with-postgresql and they suggested to post it on this mailing list.

It's months that I'm trying to solve a performance issue with PostgreSQL. I’m able to give you all the technical details needed.

SYSTEM CONFIGURATION

Our deployment machine is a Dell PowerEdge T420 with a Perc H710 RAID controller configured in this way:

• two Intel Xeon E5-2640 v2 @2Ghz
• PostgreSQL 9.4 (updated to the latest available version)

My personal low cost and low profile development machine is a MacMini configured in this way:

• one Intel i7 @2.2Ghz
  
• PostgreSQL 9.0.13 (the original built-in shipped with OS X Server)

Here are two benchmarks generated using pg_test_fsync:

T420

Query B_2 [95664.832 ms + 0.523 ms] http://explain.depesz.com/s/v06

MacMini

Query B_2 [44890.813 ms] http://explain.depesz.com/s/y7Dk

How can you sort 2,951,191 but then materialize 4,458,971 rows out of that?  I've never seen that before.  (Or, in the other plan, put 2,951,191 rows into the sort from the CTE but get 4,458,971 out of the sort?

Cheers,

Jeff