PostgreSQL Hacks - commit callback, request

Author

commit callback, request

Pavel Stehule

2006-04-05, 9:33 am

Hello

Is possible make transaction commit trigger without patching code now? I
finding way , but all usable interfaces are static. I remember on diskussion
about it and about changes in LISTEN/NOTIFY implementation. Is there any
progress?

I need it for simulation of Oracle dbms_alert.signal function. Whole
dbms_alert package is similar our LISTEN/NOTIFY. Difference is dbms_alert is
server side solution and L/N is client side. Is any chance so this
interface will be in 8.2?

Regards
Pavel Stehule

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Tom Lane

2006-04-05, 9:33 am

"Pavel Stehule" <pavel.stehule@hotmail.com> writes:
> Is possible make transaction commit trigger without patching code now?

You can get pretty close with a deferred trigger. I don't think
there's any way to have a guaranteed "at commit" trigger --- as soon
as (1) there are two of them and (2) one can get an error, the
transaction could fail after running an alleged "at commit" trigger.

regards, tom lane

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Pavel Stehule

2006-04-05, 11:34 am

>"Pavel Stehule" <pavel.stehule@hotmail.com> writes:
>
>You can get pretty close with a deferred trigger. I don't think
>there's any way to have a guaranteed "at commit" trigger --- as soon
>as (1) there are two of them and (2) one can get an error, the
>transaction could fail after running an alleged "at commit" trigger.
>
> regards, tom lane

hm. I don't have big problem with false notifications. Who want to use
dbms_alert have to calculate with this possibility. But triggers has
disadventage - I have to sometimes clean any table, which cary triggers :-(.
It's solution. I hope 8.2 will has any general mechanis. Is it possible
enhance SPI to parametrized NOTIFY? Default mode send message via libpq,
nonstandard raise any callback.

Thank You
Pavel

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Christopher Kings-Lynne

2006-04-06, 3:28 am

The only solution I know if is this patch:

http://gorda.di.uminho.pt/community/pgsqlhooks/

Chris

Pavel Stehule wrote:
> Hello
>
> Is possible make transaction commit trigger without patching code now? I
> finding way , but all usable interfaces are static. I remember on
> diskussion about it and about changes in LISTEN/NOTIFY implementation.
> Is there any progress?
>
> I need it for simulation of Oracle dbms_alert.signal function. Whole
> dbms_alert package is similar our LISTEN/NOTIFY. Difference is
> dbms_alert is server side solution and L/N is client side. Is any
> chance so this interface will be in 8.2?
>
> Regards
> Pavel Stehule
>
> ____________________
____________________
____________________
_____
> Don’t just search. Find. Check out the new MSN Search!
> http://search.msn.click-url.com/go/...6ave/direct/01/
>
>
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--
Christopher Kings-Lynne

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Tel: +618.9389.8777
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chris.kings-lynne@calorieking.com
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