RE: How to invoke stored procedures from another instance?

>
>Hi listers,
>=20
>Assume that there are two instances in Oracle. Both
>instances are on =
>different machines and different Oracle versions.
>There is a table on =
>first instance. Any update on this table should
>invoke stored procedures =
>on the second instance. This should be real time
>based. Options we =
>looked at are
>=20
>1. Trigger on the table invoking the procedures of
>the other instance
>2. Using dbms_alert
>3. Some kind of polling mechanism
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>Triggers we would like to avoid. Options we are
>left with are dbms_alert =
>and polling mechanism.=20
>=20
>Is it possible to use dbms_alert in this case? If
>yes how?
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>Can you think of some kind of polling mechanism
>which will satisfy the =
>need of real time communication? Updates on the
>table is done at a very =
>fast rate, hence processing should also be at a
>fast rate.
>=20
>Any help in this regard is very much appreciated.
>=20
>Thanks and Regards,
>=20
>Ranganath
>=20

I agree with your reluctance to use triggers; the problem is that whenever the second instance is down, then you couldn't do anything on the first. Basically, what you want to implement are near real-time although not quite synchronous snapshots. I have never used DBMS_ALERT in this way, but I think that it would be possible to have a database link on the second instance referencing the first one and invoking DBMS_ALERT through it. Beware with DBMS_ALERT though, my memories are not very fresh but there are some problems with COMMITs (which you can workaround with autonomous transactions, but then the alertee can be woken up by a rolled back transaction, a case which has to be handled by your code); DBMS_PIPE is another solution, which also has its flaws. Avanced queuing seems to me to be a fine mess, but perhaps it's worth a look too.

Regards,

Stephane Faroult
Oriole

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Author: Stephane Faroult
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