Re: prevent table polling - How?

> odysscci_at_teleport.com (Jim Kennedy) writes:
> Imagine that I have a table that I want to know when a value changes in it.
> Also imagine that I do not want to keep issueing queries against it for two
> reasons. I would rather not keep generating the network traffic and also I do
> not want to add more processing to the server.
>

 [snip]
> Then I though of pipes, but it is not clear to me if the client side keeps
> polling a pipe that it is not doing the same thing as polling the table. That
> is does reading a pipe from the client cause network packets and resource
> drain on the server? Or does the act of stuffing the pipe send the itme to
> the thing interested in the pipe's output. Is it a push from the server to
> the client or a pull (the client keeps asking if something is ready)
>

 [snip]
>>>>

Oracle pipes can be thought of as alerts with a response. They would probably experience the same problem as alerts (not giving up the cpu).

They do not have a lot of overhead, although their use would constitue network traffic (if the client & server are not the same machine)

Also, when you read a pipe "message", it is gone for good. So, if you have multiple clients needing this information, you must make sure you either use multiple pipes, or put your messages back on the pipe after you read them.

Will Kooiman Received on Sun Aug 20 1995 - 00:00:00 CEST