Обсуждение: Is there a way to kill a connection from the pg_stat_activitly list?

When you see a hanging Postgres connection (or a job running so long and you don't want to continue any more) from

select * from pg_stat_activity

and you want to disconnect it,

how do you do it?

thanks,
Jessica

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On 10/15/07, Jessica Richard <rjessil@yahoo.com> wrote:
> When you see a hanging Postgres connection (or a job running so long and you
> don't want to continue any more) from
>
> select * from pg_stat_activity
>
> and you want to disconnect it,
>
> how do you do it?

See pg_cancel_backend

You should also look at using statement_timeout if this is a regular occurrence.


--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation                | fax: 732.331.1301
499 Thornall Street, 2nd Floor          | jonah.harris@enterprisedb.com
Edison, NJ 08837                        | http://www.enterprisedb.com/

Jessica Richard wrote:
> When you see a hanging Postgres connection (or a job running so long
> and you don't want to continue any more) from
>
> select * from pg_stat_activity
>
> and you want to disconnect it,
>
> how do you do it?

|pg_cancel_backend()


|http://www.postgresql.org/docs/8.1/interactive/functions-admin.html

--
Tommy Gildseth
DBA, Gruppe for databasedrift
Universitetet i Oslo, USIT
m: +47 45 86 38 50
t: +47 22 85 29 39

Thanks a lot!

"select pg_cancel_backend(procpid) " can end the current query for that user, but then this connection becomes IDLE, still connected.

Is there a command for me to totally disconnect a user by procpid? Some times, I need to kick out a particular Postgres user completely.

thanks


Tommy Gildseth <tommy.gildseth@usit.uio.no> wrote:

Jessica Richard wrote:
> When you see a hanging Postgres connection (or a job running so long
> and you don't want to continue any more) from
>
> select * from pg_stat_activity
>
> and you want to disconnect it,
>
> how do you do it?

|pg_cancel_backend()


|http://www.postgresql.org/docs/8.1/interactive/functions-admin.html

--
Tommy Gildseth
DBA, Gruppe for databasedrift
Universitetet i Oslo, USIT
m: +47 45 86 38 50
t: +47 22 85 29 39


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On 10/15/07, Jessica Richard <rjessil@yahoo.com> wrote:
> Thanks a lot!
>
> "select pg_cancel_backend(procpid) " can end the current query for that
> user, but then this connection becomes IDLE, still connected.
>
> Is there a command for me to totally disconnect a user by procpid? Some
> times, I need to kick out a particular Postgres user completely.

From the command line on the server you can issue a kill <pid> to do
that.  From within pgsql you'd need to write a function in an
untrusted language to pull it off.

On 10/15/07, Jessica Richard <rjessil@yahoo.com> wrote:
> Thanks a lot!
>
> "select pg_cancel_backend(procpid) " can end the current query for that
> user, but then this connection becomes IDLE, still connected.
>
> Is there a command for me to totally disconnect a user by procpid? Some
> times, I need to kick out a particular Postgres user completely.

There used to be a pg_terminate_backend, but it was #ifdef'd out due
to corruption concerns.  Basically, all it did was:

kill -TERM pid

I'm not sure whether anyone has completed the research required to
know if anything remains corrupted, but it is used occasionally.  Best
to do pg_cancel_backend and then kill -TERM.


--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation                | fax: 732.331.1301
499 Thornall Street, 2nd Floor          | jonah.harris@enterprisedb.com
Edison, NJ 08837                        | http://www.enterprisedb.com/

>>> On Mon, Oct 15, 2007 at 12:34 PM, in message
<36e682920710151034r2aaef401m5429e460ee0ac209@mail.gmail.com>, "Jonah H.
Harris" <jonah.harris@gmail.com> wrote:
>
> There used to be a pg_terminate_backend, but it was #ifdef'd out due
> to corruption concerns.  Basically, all it did was:
>
> kill -TERM pid
>
> I'm not sure whether anyone has completed the research required to
> know if anything remains corrupted, but it is used occasionally.  Best
> to do pg_cancel_backend and then kill -TERM.

Where does pg_ctl kill fit in?

Is TERM the normal signal to use there, too?

Should the pg_ctl docs give some guidelines on the signals?

-Kevin

If the connection is from the local machine, I can find it with "ps -ef | grep procpid", then kill it with Unix command "kill" outside Postgres...

But I have many remote connections coming from different machines...it is hard to kill on the OS level outside Postgres on the postgres host...

I am looking for something to kill a Postgres user connection within Postgres...
Some thing like, you find the user connection with select * from pg_stat_activity...then you pick a procpid and kill right there...

Thanks,


Kevin Grittner <Kevin.Grittner@wicourts.gov> wrote:

>>> On Mon, Oct 15, 2007 at 12:34 PM, in message
<36e682920710151034r2aaef401m5429e460ee0ac209@mail.gmail.com>, "Jonah H.
Harris" wrote:
>
> There used to be a pg_terminate_backend, but it was #ifdef'd out due
> to corruption concerns. Basically, all it did was:
>
> kill -TERM pid
>
> I'm not sure whether anyone has completed the research required to
> know if anything remains corrupted, but it is used occasionally. Best
> to do pg_cancel_backend and then kill -TERM.

Where does pg_ctl kill fit in?

Is TERM the normal signal to use there, too?

Should the pg_ctl docs give some guidelines on the signals?

-Kevin




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On 10/16/07, Jessica Richard <rjessil@yahoo.com> wrote:
> If the connection is from the local machine, I can find it with "ps -ef |
> grep procpid", then kill it with Unix command "kill" outside Postgres...
>
> But I have many remote connections coming from different machines...it is
> hard to kill on the OS level outside Postgres on the postgres host...
>
> I am looking for something to kill a Postgres user connection within
> Postgres...
> Some thing like, you find the user connection with select * from
> pg_stat_activity...then you pick a procpid and kill right there...

Write a C stored procedure that takes a pid and calls kill(2), install
it on the server, and call it from SQL.

--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation                | fax: 732.331.1301
499 Thornall Street, 2nd Floor          | jonah.harris@enterprisedb.com
Edison, NJ 08837                        | http://www.enterprisedb.com/

select pg_cancel_backend(procpid) solved half of my problem...at least it terminated the query for that user... but it is still holding a user connection in IDLE state....If I have too many of those, Postgres may run of out of user connections....

I already knew how to kill a connection if the connection is from the local host. But I have many remote connections coming from different machines... hard to kill with unix command "kill"...  One time, I was testing to kill a particular connection on a testing machine, the entrie Postgres was brought down....

I need to find a safer, cleaner way to disconnect a user from Postgres when needed.

Thanks a lot,


Scott Marlowe <scott.marlowe@gmail.com> wrote:

On 10/15/07, Jessica Richard wrote:
> Thanks a lot!
>
> "select pg_cancel_backend(procpid) " can end the current query for that
> user, but then this connection becomes IDLE, still connected.
>
> Is there a command for me to totally disconnect a user by procpid? Some
> times, I need to kick out a particular Postgres user completely.

From the command line on the server you can issue a kill to do
that. From within pgsql you'd need to write a function in an
untrusted language to pull it off.

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On 10/16/07, Jessica Richard <rjessil@yahoo.com> wrote:
> select pg_cancel_backend(procpid) solved half of my problem...at least it
> terminated the query for that user... but it is still holding a user
> connection in IDLE state....If I have too many of those, Postgres may run of
> out of user connections....
>
> I already knew how to kill a connection if the connection is from the local
> host. But I have many remote connections coming from different machines...
> hard to kill with unix command "kill"...  One time, I was testing to kill a
> particular connection on a testing machine, the entrie Postgres was brought
> down....

That's why I said to write a C stored procedure to do it and install
it on the server.  That way you could call it the same way as
pg_cancel_backend.

> I need to find a safer, cleaner way to disconnect a user from Postgres when
> needed.

At this point in time, there isn't one.

--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation                | fax: 732.331.1301
499 Thornall Street, 2nd Floor          | jonah.harris@enterprisedb.com
Edison, NJ 08837                        | http://www.enterprisedb.com/

On 10/17/07, Moiz Kothari <moizpostgres@gmail.com> wrote:
> Please do not use kill

More like, please do not take advice from people who don't know what
they're talking about.

> it sometimes resets all the connection on your db,
> you might want to use

Honestly, was this supposed to be a joke?  Have you RTFM?  Have you
looked at the code to pkill?  pkill calls kill and frankly, pkill is
more dangerous if you only want to kill a single session.

Grr, I'm surprised to see such an uninformed statement on this list.

--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation                | fax: 732.331.1301
499 Thornall Street, 2nd Floor          | jonah.harris@enterprisedb.com
Edison, NJ 08837                        | http://www.enterprisedb.com/

Hi,

Please do not use kill, it sometimes resets all the connection on your db, you might want to use

pkill -f <string in ps -ef> to kill the connection you want to.

Regards,
Moiz Kothari




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