User's Manual

Chapter 10. SQL Remote Administration
Encoding and compressing messages
As messages pass through e-mail and other message systems, there is a
danger of them becoming corrupted. For example, some message systems
use certain characters or character combinations as control characters.
Message size affects the efficiency with which messages pass through a
system. Compressed messages can be processed more efficiently by a
message system than uncompressed messages. On the other hand, carrying
out compression can itself take a significant amount of time.
SQL Remote encoding
and compression
SQL Remote has a message encoding and compression scheme built in to
the Message Agent. The scheme provides the following features:
♦ Compatibility The system can be set up to be compatible with previous
versions of the software.
♦ Compression You can select a level of compression for your messages.
♦ Encoding SQL Remote encodes messages to ensure that they pass
through message systems uncorrupted. The encoding scheme can be
customized to provide extra features.
Settings for compatibility To be compatible with previous versions of the software, you should set the
database option COMPRESSION to be -1 (minus one) at each database
running the Version 6 software. This setting ensures that messages are sent
out in a format compatible with older versions of the software.
Upgrading SQL Remote If you upgrade the consolidated database Message Agent first, you should
set its COMPRESSION database option to -1. As each remote site in your
replication system is upgraded to Version 6, you can change its setting of the
COMPRESSION option to a value between 0 (no compression) and 9
(maximum compression). This allows you to take advantage of compression
features on messages being sent to the consolidated database. Once all
remote sites are upgraded, you can set the consolidated site Message Agent
COMPRESSION option to a value other than -1.
In addition, setting COMPRESSION to a value other than -1 allows you to
take advantage of the Version 6 message encoding improvements.
The encoding scheme
The default message-encoding behavior of SQL Remote is as follows:
♦ For message systems that can use binary message formats, no encoding is
carried out.
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