Chapter 2. SQL Remote Concepts
SQL Remote features
Thefollowing features are key to SQL Remote’s design.
Support formany subscribers SQLRemote is designed to support
replicationwith many subscribers to a publication.
Thisfeature is of particular importance for mobile workforce applications,
whichmay require replication to the laptop computers of hundreds or
thousandsof sales representatives from a single office database.
Transactionlog-based replication SQLRemote replication is based on
thetransaction log. Thisenables it to replicate only changes to data, rather
thanall data, in each update. Also,log-based replication has performance
advantagesover other replication systems.
Thetransaction log is the repository of all changes made to a database.
SQLRemote replicates changes made to databases as recorded in the
transactionlog. Periodically,all committed transactions in the consolidated
databasetransaction log belonging to any publication are sent to remote
databases. At remote sites, all committed transactions in the transaction log
areperiodically submitted to the consolidated database.
Byreplicating only committed transactions, SQL Remote ensures proper
transactionatomicity throughout the replication setup and maintains a
consistencyamong the databases involved in the replication, albeit with
sometime lag while the data is replicated.
Centraladministration SQL Remote is designed to be centrally
administered,at the consolidated database. Thisis particularly important for
mobileworkforce applications, where laptop users should not have to carry
outdatabase administration tasks. Itis also important in replication
involvingsmall offices that have servers but little in the way of
administrationresources.
Administrationtasks include setting up and maintaining publications,
remoteusers, and subscriptions, as well as correcting errors and conflicts if
theyoccur.
Economicalresource requirements The only software required to run
SQLRemote in addition to your Adaptive Server Anywhere or Adaptive
ServerEnterprise DBMS is the Message Agent, and a message system. If
youuse the shared file link, no message system software is required as long
aseach remote user ID has access to the directory where the message files
arestored.
Memoryand disk space requirements have been kept moderate for all
componentsof the replication system, so that you do not have to invest in
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