We find few queries running three times simultaneously with same parameters on postgres db
Hi Team 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. 2018-06-26 15:22:13.620045+05:30 | 00:00:00.198777 | active | 22234 | select * from xyz where x_id=$1 2018-06-26 15:22:13.618832+05:30 | 00:00:00.1 | active | 22233 | select * from xyz where x_id=$1 2018-06-26 15:22:13.612721+05:30 | 00:00:00.206101 | active | 23927 | select * from xyz where x_id=$1 Our application is developed in java struts 1.3 and hibernate as ORM and tomcat 8.5 for hosting. PostgreSQL version: 10.3 Kindly suggest. Thanks and Regards: Amandeep Singh
Re: We find few queries running three times simultaneously with same parameters on postgres db
Hi Andreas The value for $1 is same in all queries. @Edson: number of such running queries are always 3. Get Outlook for Android<https://aka.ms/ghei36> 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
Re: We find few queries running three times simultaneously with same parameters on postgres db
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>
From: Edson Carlos Ericksson Richter
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 qry = em.createQuery("select P from Person P where
P.city.name = :cityname");
qry.setParameter("cityname", "Porto Alegre");
qry.setMaxResults(3);
List 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
Re: We find few queries running three times simultaneously with same parameters on postgres db
Get Outlook for Android<https://aka.ms/ghei36>
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>
From: Edson Carlos Ericksson Richter
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 qry = em.createQuery("select P from Person P where
P.city.name = :cityname");
qry.setParameter("cityname", "Porto Alegre");
qry.setMaxResults(3);
List 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
