modern business are information-centric - their database-powered applications
are key company assets. As competition mounts, your customers demand increased levels of database availability
and security, including protection from downtime due to causes ranging from
hardware failure to theft of a server. They recognize that the database is
often a single point of failure not only of the applications, but overall
productivity as well.
long ago, database deployments fell under one of two distinct configurations -
centralized databases on a large server accessed by all users, or individual
database servers with limited views of the data. While these uses served
their purposes, both entailed certain limitations. A central database is a
single point of failure, and remote users with low bandwidth or sporadic
connections challenge the configuration. In decentralized structures,
maintaining an up-to-date view of the company database for all users is an equal
these trends point to new requirements on data availability; your customers require
that mission-critical data must be where users need it when they need it.
And, it must be safe and secure at all times.
Pervasive DataExchange, Pervasive's database replication
solution, addresses these issues. It reliably moves data between two or
more Pervasive.SQL databases to maintain warm backup systems, drive data into
reporting servers, or synchronize multiple remote databases.
DataExchange technology works by capturing and sharing changes from one
Pervasive.SQL database to other databases in a DataExchange replication
network. Each database is augmented with DataExchange, which adds two
software components to a Pervasive.SQL database, the Replication Event Handler
and the Replication Engine.
Replication Event Handler (REH) plugs directly into the Pervasive.SQL
database engine. Specifically, the REH is a set of DLLs that operate
within the database engine, so if the database is running, the replication
event handler is running as well. The database engine activates the
REH when there is a change event (insert, update, delete). The REH
then makes note of the event in one of its private control tables.
Replication Engine is a separate process that performs the actual
replication task. It reads the control tables to determine what
records have changed since the last replication session. It then
groups these into packets and shares them with the other replication engines
participating in the DataExchange network. These other engines then
apply the updates to their own databases. The replication process
occurs either continuously, or at scheduled intervals, or on demand.
The replication engine does not require constant network connectivity, so
DataExchange is suitable for scenarios with intermittent connectivity, like
remote users with dialup connections.
normally occurs at the transactional (Btrieve) level, so data definition
files (DDFs) are not required.
are encrypted using a 128-bit key. This enhances security by
eliminating the possibility of unauthorized viewing of the database changes.
are detected and resolved. Conflicts occur when the same record in two
databases is edited at the same time. In most applications, data
conflicts are rare or nonexistent. In cases where data conflicts may
occur, there are default and user-definable resolution rules.
topology is flexible. While most DataExchange networks include only
two databases replicating back and forth, multiple database scenarios and
organizations are possible. Supported topologies include ring, hub and
spoke, peer to peer and hierarchical.
data segmentation is possible. This includes vertical (particular
columns are treated as a unit), horizontal (groups of records are treated as
a unit) and referential (records from different tables that are linked by a
referential integrity structure are treated as a unit). This allows
tight control over what set of database content is replicated where.
addition, DataExchange includes a full suite of design, maintenance and
Pervasive DataExchange is in use around the world, generating
value for customers in different ways. Read what they have to say:
recovery: DataExchange drives data from a production server to a warm backup
at an offsite location. Says Brian Swords, vice president , Corporate
Trust, Bank of New York, "Pervasive's database replication
technology and willingness to provide immediate support have been critical
to our disaster recovery efforts following the World Trade Center
Data sharing: DataExchange synchronizes multiple
databases, giving a unified view of data across databases and
geographies. Says Jan Molenaar, ICT manager, Ubbink Garden, "We
are so satisfied with the Pervasive DataExchange solution that we are
planning to extend it to our other locations. This will spread the
benefits of our real-time data-sharing network throughout the entire
reporting: DataExchange loads the database of a reporting server or web site
with fresh content from a production server. Says Henry White. court
IT director, Court System of Gwinnet County, Giorgia, "Pervasive's
DataExchange will power the link between our justice information system and
the Web portal, driving data to the portal and eliminating costly
application development tasks."