NetBase SQL Shadowing Handbook

ver A0195 QUEST Software, Inc. 1-1
Chapter 1
Introduction
Who should use this handbook?
The purpose of this handbook is to address the issues of customers who are interested in SQL
shadowing without using any of the other NetBase features. For customers who are adding SQL
shadowing to their other NetBase services, such as NFA, shadowing, spooling, or statistics, the
NetBase reference manual is the appropriate text.
NetBase SQL shadowing uses a small fraction of the NetBase product. By default, when you
initiate NetBase, it expects you to be using some of the other services. From this handbook, you
will learn to modify those defaults, instructing NetBase to perform only SQL shadowing. This
handbook will outline all of the steps necessary to fully implement SQL shadowing, giving
examples of applications of all of the options.
NetBase SQL Shadowing
NetBase SQL shadowing consists of an export process and an import process which call routines
from the Warm Standby Logging library in order to shadow an ALLBASE DBE. Warm Standby
Logging (WSL) is a feature of SQL provided by HP. Warm Standby Logging with NetBase can
be used to shadow a DBE on one node to copies on more than one node, or it may be used to
shadow DBEs on multiple nodes to one consolidated copy. Also, it can be used for concurrent
updating of multiple DBEs.
NetBase SQL shadowing can involve an entire DBE, or you may use it to include or exclude
specific tables within a DBE. In addition, you may invoke user exits to re-route or ignore shadow
information before it is passed into the network. You may read transactions out of the logfile,
without sending them across to shadow machines by setting up an export user exit in a design
we refer to as a "pseudo-node." Using a pseudo-node user exit, you can log all updates or
deletes (or both), or perform other analysis of the DBE activity without transmitting to the remote
nodes.
On the remote side, you can write user exits that ignore data, re-route data to other nodes, or do
additional processing before the data is posted to the database. Finally, a user exit may be called
if an error was encountered during the update of the shadow.
The key to all of this is the partition number. Updates made to a DBE by users are identified by
the home partition number. Updates made to a DBE by the WSL routines will be identified by the
home partition number on the originating machine. In this way two DBEs can be shadowed both
ways. The export process should be configured on each machine to only send the updates made
by the local users.