Re: Centos 6.9 and centos 7

On 12/04/2017 02:19 PM, Nicola Contu wrote:
...>
> centos 7 : 
>
> dbname=# \timing Timing is on. cmdv3=# SELECT id FROM
> client_billing_account WHERE name = 'name'; id ------- ***** (1 row)
> Time: 3.884 ms
>
> centos 6.9
>
> dbname=# SELECT id FROM client_billing_account WHERE name = 'name'; id
> ------- ***** (1 row) Time: 1.620 ms
>

We need to see EXPLAIN (ANALYZE,BUFFERS) for the queries.

Are those VMs or bare metal? What CPUs and RAM are there? Have you
checked that power management is disabled / cpufreq uses the same
policy? That typically affects short CPU-bound queries.

Other than that, I recommend performing basic system benchmarks (CPU,
memory, ...) and only if those machines perform equally should you look
for issues in PostgreSQL. Chances are the root cause is in hw or OS, in
which case you need to address that first.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services