From: Justin Pryzby <pryzby@telsasoft.com>
To: Rambabu g <rambabu.g2564@gmail.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: HIGH IO and Less CPU utilization
Date: Tue, 29 Mar 2022 14:39:41 -0500
Message-ID: <20220329193941.GB28503@telsasoft.com> (raw)
In-Reply-To: <CADdgF6co=CgJBXmyNwE_GRg-Kayw5fe5WAeUQ8LDLs8s2Da_sQ@mail.gmail.com>
References: <CADdgF6ecxpubq-wm4bcDCyj3yt6uNjJgXKcdCS2Jn+NvE4abFw@mail.gmail.com>
<20220329182453.GA28503@telsasoft.com>
<CADdgF6co=CgJBXmyNwE_GRg-Kayw5fe5WAeUQ8LDLs8s2Da_sQ@mail.gmail.com>
On Wed, Mar 30, 2022 at 12:52:05AM +0530, Rambabu g wrote:
> > What indexes are defined on this table ?
> > How large are they ?
>
> There are three indexes defined on the table, each one is around 20 to 25GB
> and the indexes is create on
Did you mean to say something else after "on" ?
Show the definition of the indexes from psql \d
> postgres=# explain select distinct empno from emp where sname='test' and tp='EMP NAME 1'
Is this the only query that's performing poorly ?
You should send explain (analyze,buffers) for the prolematic queries.
> > > Hypervisor vendor: KVM
> >
> > Are KSM or THP enabled on the hypervisor ?
> No, the Ec2 VM is delicate to postgres DB instances only.
Oh, so this is an EC2 and you cannot change the hypervisor itself.
> -bash-4.2$ tail /sys/kernel/mm/ksm/run /sys/kernel/mm/transparent_hugepage/khugepaged/defrag /sys/kernel/mm/transparent_hugepage/enabled /sys/kernel/mm/transparent_hugepage/defrag
...
> ==> /sys/kernel/mm/transparent_hugepage/defrag <==
> [always] madvise never
I doubt it will help, but you could try disabling these.
It's a quick experiment anyway.
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To: pgsql-performance@postgresql.org
Cc: pryzby@telsasoft.com, rambabu.g2564@gmail.com, pgsql-performance@lists.postgresql.org
Subject: Re: HIGH IO and Less CPU utilization
In-Reply-To: <20220329193941.GB28503@telsasoft.com>
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