HP Integrity NonStop J-Series - Manual (Page 17)

HP NonStop SQL DDL Replicator User’s Guide —545799-007
1-1
1
Introducing SDR
This manual describes HP NonStop SQL DDL Replicator (SDR). This section is an
introduction to SDR. The information is organized as follows:
Introduction
Product Overview
SDR Components
NonStop Kernel and RDF Compatibility
Introduction
HP NonStop SQL DDL Replicator (SDR) is a companion to the NonStop Remote
Database Facility (RDF) subsystem. It provides the ability to automatically replicate
SQL DDL operations to a backup system in the same way that RDF replicates
database updates to a backup database.
The initial release of SDR supports NonStop SQL/MP. All further references to SQL
implies SQL/MP only. Also, all further references to DDL refer to NonStop SQL/MP
DDL operations.
RDF uses TMF audit trail information to capture changes to a primary database and to
replicate those changes to one or more backup copies of the database, usually on one
or more remote systems. In the case of a planned or unplanned outage of a primary
database system, the backup copies may be used to continue operations after a
takeover operation.
Since the necessary information is not present in the TMF audit trail, RDF does not
replicate DDL operations such as CREATE, DROP, and ALTER. In order to safely
perform these operations in a standard RDF environment, HP recommends stopping
all primary system applications, and stopping TMF and RDF (See RDF 5. – RDF and
NonStop SQL/MP DDL Operations).
SDR performs a series of operations to both capture DDL operations and to replicate
them on the backup database. It does this quickly, automatically, without user
intervention and without affecting applications or stopping TMF or RDF. SDR replicates
all DDL operations that are executed by SQLCI, user applications, or access utilities
like ODBC. No change to user applications is required.
Note. Since SDR is an extension of RDF, this document assumes the reader has a good
working knowledge of RDF and frequently makes reference to the HP NonStop RDF System
Management Manual for J-series and H-Series RVUs (RDF <RVU-id>) in the following form:
(RDF 5. – Stopping RDF), which is the paragraph heading “Stopping RDF” in chapter 5 of the
RDF manual.