User's Manual

Chapter 2. SQL Remote Concepts
SQL Remote features
The following features are key to SQL Remote’s design.
Support for many subscribers SQL Remote is designed to support
replication with many subscribers to a publication.
This feature is of particular importance for mobile workforce applications,
which may require replication to the laptop computers of hundreds or
thousands of sales representatives from a single office database.
Transaction log-based replication SQL Remote replication is based on
the transaction log. This enables it to replicate only changes to data, rather
than all data, in each update. Also, log-based replication has performance
advantages over other replication systems.
The transaction log is the repository of all changes made to a database.
SQL Remote replicates changes made to databases as recorded in the
transaction log. Periodically, all committed transactions in the consolidated
database transaction log belonging to any publication are sent to remote
databases. At remote sites, all committed transactions in the transaction log
are periodically submitted to the consolidated database.
By replicating only committed transactions, SQL Remote ensures proper
transaction atomicity throughout the replication setup and maintains a
consistency among the databases involved in the replication, albeit with
some time lag while the data is replicated.
Central administration SQL Remote is designed to be centrally
administered, at the consolidated database. This is particularly important for
mobile workforce applications, where laptop users should not have to carry
out database administration tasks. It is also important in replication
involving small offices that have servers but little in the way of
administration resources.
Administration tasks include setting up and maintaining publications,
remote users, and subscriptions, as well as correcting errors and conflicts if
they occur.
Economical resource requirements The only software required to run
SQL Remote in addition to your Adaptive Server Anywhere or Adaptive
Server Enterprise DBMS is the Message Agent, and a message system. If
you use the shared file link, no message system software is required as long
as each remote user ID has access to the directory where the message files
are stored.
Memory and disk space requirements have been kept moderate for all
components of the replication system, so that you do not have to invest in
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