We find few queries running three times simultaneously with same parameters on postgres db

Am 26.06.2018 um 12:19 schrieb amandeep singh:

We have been observing our postgres database from past few days,We
found few queries running three times simultaneously with same
parameters.I would like to back track how a query is running multiple
times.

they are independend each other. You can run those queries with EXPLAIN
ANALYSE to see the execution plan.

Regards, Andreas

--
2ndQuadrant - The PostgreSQL Support Company.
www.2ndQuadrant.com

Am 26.06.2018 um 12:19 schrieb amandeep singh:

We have been observing our postgres database from past few days,We found
few queries running three times simultaneously with same parameters.I would
like to back track how a query is running multiple times.

Can you check the requests made by your application/ ORM? This looks like
application is making multiple requests, rather than something happening on
the database?

Em 26/06/2018 08:49, Saurabh Agrawal escreveu:

Am 26.06.2018 um 12:19 schrieb amandeep singh:

We have been observing our postgres database from past few
days,We found few queries running three times simultaneously
with same parameters.I would like to back track how a query is
running multiple times.

Can you check the requests made by your application/ ORM? This looks
like application is making multiple requests, rather than something
happening on the database?

I agree with Saurabh Agrawal.
Sometimes, users just double (or triple) click a form button, and then
resulting activity is executed more than once...
What I used is to deactivate buttons after first click. This is even
more noticeable when working on intranet apps ou high speed internet
connections.

Users, sometimes, need to be educated that one click is enough :-)

Regards,

Edson.

On 26 June 2018 12:32:44 CEST, Andreas Kretschmer <andreas@a-kretschmer.de> wrote:

Am 26.06.2018 um 12:19 schrieb amandeep singh:

We have been observing our postgres database from past few days,We
found few queries running three times simultaneously with same
parameters.I would like to back track how a query is running multiple

times.

they are independend each other. You can run those queries with EXPLAIN

ANALYSE to see the execution plan.

Regards, Andreas

seems like i misunderstud your query. are you sure, that the parameter $1 is equal across all different connections?

Andreas

--
2ndQuadrant - The PostgreSQL Support Company

Hi Andreas

The value for $1 is same in all queries.

@Edson: number of such running queries are always 3.

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From: Andreas Kretschmer
Sent: Tuesday, 26 June, 6:04 PM
Subject: Re: We find few queries running three times simultaneously with same parameters on postgres db
To: pgsql-general@lists.postgresql.org

On 26 June 2018 12:32:44 CEST, Andreas Kretschmer wrote: > > >Am 26.06.2018 um 12:19 schrieb amandeep singh: >> We have been observing our postgres database from past few days,We >> found few queries running three times simultaneously with same >> parameters.I would like to back track how a query is running multiple > >> times. > >they are independend each other. You can run those queries with EXPLAIN > >ANALYSE to see the execution plan. > >Regards, Andreas seems like i misunderstud your query. are you sure, that the parameter $1 is equal across all different connections? Andreas -- 2ndQuadrant - The PostgreSQL Support Company

On Tue, Jun 26, 2018 at 1:26 PM, amandeep singh <singh_a@live.in> wrote:

Hi Andreas

The value for $1 is same in all queries.

@Edson: number of such running queries are always 3.

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From: Andreas Kretschmer
Sent: Tuesday, 26 June, 6:04 PM
Subject: Re: We find few queries running three times simultaneously with
same parameters on postgres db
To: pgsql-general@lists.postgresql.org

On 26 June 2018 12:32:44 CEST, Andreas Kretschmer wrote: > > >Am
26.06.2018 um 12:19 schrieb amandeep singh: >> We have been observing our
postgres database from past few days,We >> found few queries running three
times simultaneously with same >> parameters.I would like to back track how
a query is running multiple > >> times. > >they are independend each other.
You can run those queries with EXPLAIN > >ANALYSE to see the execution
plan. > >Regards, Andreas seems like i misunderstud your query. are you
sure, that the parameter $1 is equal across all different connections?
Andreas -- 2ndQuadrant - The PostgreSQL Support Company

This query will show you the pid, client_addr and user that submitted the
queries, in addition to other useful information.

SELECT backend_start as be_start,
datname,
pid as pid,
client_addr,
usename as user,
state,
query,
wait_event_type,
query_start,
current_timestamp - query_start as duration
FROM pg_stat_activity
WHERE pg_backend_pid() <> pid
ORDER BY 1,
datname,
query_start;

--
*Melvin Davidson*
*Maj. Database & Exploration Specialist*
*Universe Exploration Command – UXC*
Employment by invitation only!

Em 26/06/2018 14:26, amandeep singh escreveu:

Hi Andreas

The value for $1 is same in all queries.

@Edson: number of such running queries are always� 3.

I see. It seems a programming logic error to me.
I also use JPA (Hibernate and/or EclipseLink) and I don't have such problem.
But I could replicate your scenario doing the following (with
EclipseLink, didn't test with Hibernate):

1) In persistence.xml, disable all caches (this is very important for
make reproducible)
2) Load three Person records that live on same city (objects Person and
City mapped to tables Person and City, being city an attribute of Person
object):

TypedQuery<Person> qry = em.createQuery("select P from Person P where
P.city.name = :cityname");
qry.setParameter("cityname", "Porto Alegre");
qry.setMaxResults(3);
List<Person> rs = qry.getResultList();

3) This will cause one query against Person table, and exactly 3 queries
issued with same parameters to City table.

I really don't know how your code works, and is quite hard to guess, but
as you can see, it is easy to reproduce similar behavior.
Now, if I enable EclipseLink caches, only one query is issued for each
City key - so, I'll have one query for Person and one query for� only.

Hope this helps to enlighten your problem.

:-)

Regards,

Edson

Thanks Edson for ur support.

As I am not a developer , I will share this test case with development team.

Once I get feedback from team, will share it on this mailing list.

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From: Edson Carlos Ericksson Richter <richter@simkorp.com.br>
Sent: Wednesday, June 27, 2018 2:02:19 PM
To: pgsql-general@lists.postgresql.org
Subject: Re: We find few queries running three times simultaneously with same parameters on postgres db

Em 26/06/2018 14:26, amandeep singh escreveu:

Hi Andreas

The value for $1 is same in all queries.

@Edson: number of such running queries are always 3.

I see. It seems a programming logic error to me.
I also use JPA (Hibernate and/or EclipseLink) and I don't have such problem.
But I could replicate your scenario doing the following (with
EclipseLink, didn't test with Hibernate):

1) In persistence.xml, disable all caches (this is very important for
make reproducible)
2) Load three Person records that live on same city (objects Person and
City mapped to tables Person and City, being city an attribute of Person
object):

TypedQuery<Person> qry = em.createQuery("select P from Person P where
P.city.name = :cityname");
qry.setParameter("cityname", "Porto Alegre");
qry.setMaxResults(3);
List<Person> rs = qry.getResultList();

3) This will cause one query against Person table, and exactly 3 queries
issued with same parameters to City table.

I really don't know how your code works, and is quite hard to guess, but
as you can see, it is easy to reproduce similar behavior.
Now, if I enable EclipseLink caches, only one query is issued for each
City key - so, I'll have one query for Person and one query for only.

Hope this helps to enlighten your problem.

:-)

Regards,

Edson

Get Outlook for Android<https://aka.ms/ghei36&gt;

From: amandeep singh
Sent: Wednesday, 27 June, 8:42 PM
Subject: Re: We find few queries running three times simultaneously with same parameters on postgres db
To: pgsql-general@lists.postgresql.org, Edson Carlos Ericksson Richter

Thanks Edson for ur support.

As I am not a developer , I will share this test case with development team.

Once I get feedback from team, will share it on this mailing list.

Get Outlook for Android<https://aka.ms/ghei36&gt;

From: Edson Carlos Ericksson Richter <richter@simkorp.com.br>
Sent: Wednesday, June 27, 2018 2:02:19 PM
To: pgsql-general@lists.postgresql.org
Subject: Re: We find few queries running three times simultaneously with same parameters on postgres db

Em 26/06/2018 14:26, amandeep singh escreveu:

Hi Andreas

The value for $1 is same in all queries.

@Edson: number of such running queries are always 3.

I see. It seems a programming logic error to me.
I also use JPA (Hibernate and/or EclipseLink) and I don't have such problem.
But I could replicate your scenario doing the following (with
EclipseLink, didn't test with Hibernate):

1) In persistence.xml, disable all caches (this is very important for
make reproducible)
2) Load three Person records that live on same city (objects Person and
City mapped to tables Person and City, being city an attribute of Person
object):

TypedQuery<Person> qry = em.createQuery("select P from Person P where
P.city.name = :cityname");
qry.setParameter("cityname", "Porto Alegre");
qry.setMaxResults(3);
List<Person> rs = qry.getResultList();

3) This will cause one query against Person table, and exactly 3 queries
issued with same parameters to City table.

I really don't know how your code works, and is quite hard to guess, but
as you can see, it is easy to reproduce similar behavior.
Now, if I enable EclipseLink caches, only one query is issued for each
City key - so, I'll have one query for Person and one query for only.

Hope this helps to enlighten your problem.

:-)

Regards,

Edson