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
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SQL/MX Distributed Database Features
User Data Distribution
You can distribute tables and indexes across nodes in an Expand network or allow
them to reside intact on single nodes.
User database objects, including base tables, indexes, and views, are distributed with
the LOCATION clause in DDL and utility operations. Distribution of user data is an
explicit user action. NonStop SQL/MX does not impose limits on the number of nodes
to which user database objects can be distributed.
Catalog Reference
SQL/MX database objects have location-independent ANSI names. The actual data is
represented in Guardian files with location-dependent Guardian file names. The
information needed to resolve an ANSI name to the corresponding set of Guardian file
names (ANSI name lookup) is stored in SQL/MX metadata.
Metadata definitions for database objects are stored in metadata tables in definition
schemas. One definition schema holds the metadata for all schemas of a given version
in a catalog. A DDL or utility operation can add, remove, or modify rows in the
appropriate definition schema for the affected database object's catalog.
You use catalog references to identify the node on which the metadata for a given
catalog resides. Several types of catalog references are used. An automatic catalog
reference for a catalog occurs on the node where the catalog is created and the
metadata for all the database objects in that catalog resides. A given catalog can have
only one automatic reference node in the distributed database. An empty (or manual)
catalog reference occurs for every node on which the catalog has been registered from
node where the catalog was created. The system schema tables on empty catalog
reference nodes contain information about the catalog and its node that enables these
nodes to locate and query objects in the catalog. A node on which a catalog has not
been created or registered contains no catalog reference cannot detect the catalog, its
objects, or its metadata.
Release 2.1 and Release 2.0 support catalog reference but not object metadata
replication. A catalog reference can be registered for remote nodes, providing them
with the catalog registration metadata needed to access the catalog’s object metadata
on the node where the catalog was created. Object metadata for any user catalog,
including all metadata definitions, remains on the node where the catalog was created
and cannot be replicated to other nodes in the network. Therefore, object metadata
replication cannot be used.
ANSI Name Lookup
ANSI name lookup encompasses:
•
ANSI-name-to-Guardian name resolution
•
Metadata definition lookup using ANSI names