Meaning of query age in pg_stat_activity

[Jan De Moerloose]

Hi,

I'm using the following to detect long running queries in a webapp that is
high on cpu:

SELECT pid, age(clock_timestamp(),query_start) as age, usename, query,
state from pg_stat_activity order by age;

When the cpu is 100% and the app slowing down, i can see that some queries
have a long age.
Running the same queries in psql is very fast, however. The db itself is
low on cpu.

Is the age value as i calculate it representing the time spent by the
database to execute the query or does it also include the time to read the
result ? In other words, if the client is starving on cpu, will i see
higher values of age ?

Regards,
Jan

Re: Meaning of query age in pg_stat_activity

[Jan De Moerloose]

The state is 'idle in transaction'.

On Tue, Jan 30, 2018 at 12:10 AM, Nikolay Samokhvalov  wrote:

> On Mon, Jan 29, 2018 at 3:06 PM, Jan De Moerloose 
> wrote:
> ...
>
>> SELECT pid, age(clock_timestamp(),query_start) as age, usename, query,
>> state from pg_stat_activity order by age;
>>
>> When the cpu is 100% and the app slowing down, i can see that some
>> queries have a long age.
>>
>
> What is the value of "state" column for those queries?
>
>

Re: Meaning of query age in pg_stat_activity

[Jan De Moerloose]

So the query is just the latest query and the time is the transaction time
since this query, i suppose ?
Thanks for your answer, i will try to make the transaction shorter as you
suggest.

On Tue, Jan 30, 2018 at 12:29 AM, Nikolay Samokhvalov  wrote:

> On Mon, Jan 29, 2018 at 3:19 PM, Jan De Moerloose 
> wrote:
>
>> The state is 'idle in transaction'.
>>
>
> So you have long-running *transactions*, not queries. This is not good for
> an OLTP system, because some transaction can wait of others, which are
> "idle in transaction" but do nothing at the moment. Think how you can make
> them shorter, commit faster.
>
> Also, if your server version is 9.6+ consider setting
> idle_in_transaction_session_timeout to some low value:
> https://www.postgresql.org/docs/current/static/runtime-
> config-client.html#GUC-IDLE-IN-TRANSACTION-SESSION-TIMEOUT
>
>