How to disconnect a single user in Postgresql 8.2.5 from a database

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How to disconnect a single user in Postgresql 8.2.5 from a database ?
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Re: How to disconnect a single user in Postgresql 8.2.5 from

On 19 April 2010 15:27, Steph L wrote:
>
> How to disconnect a single user in Postgresql 8.2.5 from a database ?

AFAIK the only way is to upgrade to 8.4 and use pg_terminate_backend():
http://www.postgresql.org/docs/8.4/interactive/functions-adm in.html

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Re: How to disconnect a single user in Postgresql 8.2.5 from

On Mon, Apr 19, 2010 at 11:52 AM, Sergey Konoplev wrote:
> On 19 April 2010 15:27, Steph L wrote:
>> How to disconnect a single user in Postgresql 8.2.5 from a database ?
> AFAIK the only way is to upgrade to 8.4 and use pg_terminate_backend():
> http://www.postgresql.org/docs/8.4/interactive/functions-adm in.html

pg_terminate_backend() is just a SQL wrapper around:
kill -SIGTERM [backend PID]

For versions before 8.4: if you can SSH in to the server, run the
above on the PID of the backend your user is connected to, and that
should terminate their connection.

Josh

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Re: How to disconnect a single user in Postgresql 8.2.5 from a database

Josh Kupershmidt writes:
> pg_terminate_backend() is just a SQL wrapper around:
> kill -SIGTERM [backend PID]

> For versions before 8.4: if you can SSH in to the server, run the
> above on the PID of the backend your user is connected to, and that
> should terminate their connection.

The reason the function isn't there before 8.4 is that that's not
promised to work before 8.4 ... most of the time it will work, but
once in awhile you could get nasty side-effects.

regards, tom lane

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Re: How to disconnect a single user in Postgresql 8.2.5 from

On Mon, Apr 19, 2010 at 8:10 PM, Tom Lane wrote:
> Josh Kupershmidt writes:
>> pg_terminate_backend() is just a SQL wrapper around:
>> =A0 =A0kill -SIGTERM [backend PID]
>
>> For versions before 8.4: if you can SSH in to the server, run the
>> above on the PID of the backend your user is connected to, and that
>> should terminate their connection.
>
> The reason the function isn't there before 8.4 is that that's not
> promised to work before 8.4 ... most of the time it will work, but
> once in awhile you could get nasty side-effects.

So, pg_cancel_backend(pid) is the 8.3 version, that may or may not
always work then, right?

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Re: How to disconnect a single user in Postgresql 8.2.5 from a database

Scott Marlowe writes:
> On Mon, Apr 19, 2010 at 8:10 PM, Tom Lane wrote:
>> The reason the function isn't there before 8.4 is that that's not
>> promised to work before 8.4 ... most of the time it will work, but
>> once in awhile you could get nasty side-effects.

> So, pg_cancel_backend(pid) is the 8.3 version, that may or may not
> always work then, right?

No, I didn't say that.

regards, tom lane

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Re: How to disconnect a single user in Postgresql 8.2.5 from a database

pg_cancel_backend() and pg_terminate_backend() do different things.
From the documentation:

pg_cancel_backend(pid int) Cancel a backend's current query
pg_terminate_backend(pid int) Terminate a backend



On 4/19/2010 11:07 PM, Scott Marlowe wrote:
> On Mon, Apr 19, 2010 at 8:10 PM, Tom Lane wrote:
>> Josh Kupershmidt writes:
>>> pg_terminate_backend() is just a SQL wrapper around:
>>> kill -SIGTERM [backend PID]
>>
>>> For versions before 8.4: if you can SSH in to the server, run the
>>> above on the PID of the backend your user is connected to, and that
>>> should terminate their connection.
>>
>> The reason the function isn't there before 8.4 is that that's not
>> promised to work before 8.4 ... most of the time it will work, but
>> once in awhile you could get nasty side-effects.
>
> So, pg_cancel_backend(pid) is the 8.3 version, that may or may not
> always work then, right?
>


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Re: How to disconnect a single user in Postgresql 8.2.5 from

On Tue, Apr 20, 2010 at 7:31 AM, Tom Lane wrote:
> Scott Marlowe writes:
>> On Mon, Apr 19, 2010 at 8:10 PM, Tom Lane wrote:
>>> The reason the function isn't there before 8.4 is that that's not
>>> promised to work before 8.4 ... most of the time it will work, but
>>> once in awhile you could get nasty side-effects.
>
>> So, pg_cancel_backend(pid) is the 8.3 version, that may or may not
>> always work then, right?
>
> No, I didn't say that.

Well, my experience with it has been that it's similar and it doesn't
always work.

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Re: How to disconnect a single user in Postgresql 8.2.5 from

Ahhh, ok.

On Tue, Apr 20, 2010 at 7:52 AM, Lewis Kapell wrote:
> pg_cancel_backend() and pg_terminate_backend() do different things. From =
the
> documentation:
>
> pg_cancel_backend(pid int) =A0 =A0 =A0Cancel a backend's current query
> pg_terminate_backend(pid int) =A0 Terminate a backend
>
>
>
> On 4/19/2010 11:07 PM, Scott Marlowe wrote:
>>
>> On Mon, Apr 19, 2010 at 8:10 PM, Tom Lane =A0wrote:
>>>
>>> Josh Kupershmidt =A0writes:
>>>>
>>>> pg_terminate_backend() is just a SQL wrapper around:
>>>> =A0 =A0kill -SIGTERM [backend PID]
>>>
>>>> For versions before 8.4: if you can SSH in to the server, run the
>>>> above on the PID of the backend your user is connected to, and that
>>>> should terminate their connection.
>>>
>>> The reason the function isn't there before 8.4 is that that's not
>>> promised to work before 8.4 ... most of the time it will work, but
>>> once in awhile you could get nasty side-effects.
>>
>> So, pg_cancel_backend(pid) is the 8.3 version, that may or may not
>> always work then, right?
>>
>
>
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>



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Re: How to disconnect a single user in Postgresql 8.2.5 from a database

Scott Marlowe writes:
> On Tue, Apr 20, 2010 at 7:31 AM, Tom Lane wrote:
>> Scott Marlowe writes:
>>> So, pg_cancel_backend(pid) is the 8.3 version, that may or may not
>>> always work then, right?
>>
>> No, I didn't say that.

> Well, my experience with it has been that it's similar and it doesn't
> always work.

pg_cancel_backend might or might not always succeed in canceling a
query, if that's what you mean. What I'm worried about with SIGTERM'ing
an individual backend is negative side-effects, like hanging the entire
database. Before 8.4 there was never any attempt to ensure that that
would work nicely, and if memory serves we did find some problems when
we tested it.

regards, tom lane

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