SQL/MX 2.x Installation and Management Guide (G06.24+, H06.03+)

Managing an SQL/MX Distributed Database
HP NonStop SQL/MX Installation and Management Guide—523723-004
13-14
Maintaining Local Autonomy in a Network
configurations with respect to their ability to minimize the consequences of node loss
on surviving network nodes.
Network Outage Failure Scenario
Suppose that you have an SQL/MX database that is distributed across three nodes (\A,
\B, and \C). The database includes two user catalogs, CAT_1 and CAT_2, which were
created on node \B and have been registered for nodes \A and \C.
Table 13-3 describes the status of each node in the network with respect to user data,
object metadata, applications for CAT_1 and CAT_2, and the effects of the loss of
each node on the other two nodes in the network:
•
The column “CAT_1 and CAT_2 User Data Present?” identifies whether user data
for CAT_1 and CAT_2 objects is present on a given node in the network.
•
The column “CAT_1 and CAT_2 Metadata Present?” identifies whether object
metadata for CAT_1 and CAT_2 is present on a given node. Only node \B, where
the catalogs CAT_1 and CAT_2 were created, contains this object metadata
because catalog and schema replication is not supported with Release 2.1 or
Release 2.0.
•
The column “CAT_1 and CAT_2 Applications Present?” identifies whether
application programs that contain queries to CAT_1 and CAT_2 objects are
present on a given node.
•
The column “Consequences of Losing This Node on the Other Nodes” describes
how the loss of a given node affects the other two nodes in the network.
Table 13-3. Consequences of Network Node Loss, Original Configuration
Node
CAT_1 and
CAT_2
User Data
Present?
CAT_1 and
CAT_2
Metadata
Present?
CAT_1 and
CAT_2
Applications
Present?
Consequences of Losing
This Node on the Other
Nodes
\A Yes No Yes From nodes \B and \C, you
cannot perform DDL or utility
operations on objects
partitioned across node \A.
You cannot perform statically-
compiled DML operations that
require data stored on node
\A.