messages are flushed in a least-recently-used fashion.

This option is provided primarily for customers considering a single consolidated database for thousands of remote databases.

Tuning incoming message polling

When running a Message Agent in continuous mode, typically at a consolidated database site, you can control how often it polls for incoming messages, and how “patient” it is in waiting for messages that arrive out of order before requesting that the message be resent. Tuning these aspects of the behavior can have a significant effect on performance in some circumstances.

Issues to consider

The issues to consider when tuning the message-receiving process are

 

similar to those when tuning the message-sending process.

 

Regular messages

Your choices dictate how often the Message Agent

 

polls for incoming messages from remote databases.

 

Resend requests

You can control how many polls to wait until an

out-of-order message arrives, before requesting that it be resent.

Processing incoming messages If your polling period for incoming messages is too long, compared to the frequency with which messages are arriving, you could end up with messages sitting in the queue, waiting to be processed. If your polling period is too short, you will waste resources polling when no messages are in the queue.

For more information on the message sending process, see “Tuning the message sending process” on page 232 .

Polling interval

By default, a Message Agent running in continuous mode polls one minute after finishing the previous poll, to see whether new messages have arrived. You can configure the polling interval using the -rdoption.

The default polling interval from the end of one poll to the start of another is one minute. You can poll more frequently using a value in seconds, as in the following command line:

dbremote -rd 30s

Alternatively, you can poll less frequently, as in the following command line, which polls every five minutes:

dbremote -rd 5

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Sybase DC38133-01-0902-01 manual Tuning incoming message polling, Polling interval