SQL/MX 3.2 Management Manual (H06.25+, J06.14+)

Table Of Contents
“Multiple Character Sets” (page 20)
“Database Security” (page 20)
“Parallel Processing” (page 20)
“High Availability” (page 21)
Distributed Databases
An SQL/MX database distributed across multiple nodes in an Expand network provides a high
level of transparency, location independence, read and update capability, and data integrity.
Objects in the same database can reside on different compatible nodes. The partitions of a table
or index can also be spread across compatible nodes.
A distributed database can be managed by a central site, by each independent distributed site,
or by a combination of these.
For SQL/MX distributed databases with SQL/MX tables, local autonomy is limited because of the
absence of true metadata replication from local to remote nodes. As such, local node autonomy
is confined to local data whose metadata exists on the local node.
For more information, see “Managing an SQL/MX Distributed Database” (page 263).
Database Protection and Recovery
An SQL/MX database is protected by:
The HP NonStop Transaction Management Facility (TMF), which audits database changes
and provides automatic recovery.
TMF provides automatic online recovery of audited SQL/MX objects and files by using audit
trails. A transaction currently in progress can be aborted if a failure or error condition is
detected. TMF terminates the transaction and restores the database to its state before the
beginning of the transaction. TMF provides two additional recovery mechanisms:
Volume recovery, which recovers the database in the event of a disk crash or system
failure.
File recovery, which reconstructs specific audited files when the current copies on the
data volume are not usable (for example, if a system or media failure jeopardizes the
consistency of one or more audited files).
The HP NonStop Remote Database Facility (RDF), which monitors changes made to a production
database on a local (primary) system and maintains a copy of that database on a remote
(backup) system.
The RDF subsystem enables you to use the backup database as a read-only resource to balance
the overall workload and improve response times. Activities at the backup system can include
querying the database, processing heavy batch-reporting loads, and consolidating data from
multiple sites into one central site. For more information, see the RDF/IMP, IMPX, and ZLT
System Management Manual.
The Guardian Backup and Restore 2 utility, which you can use to perform tape backups and
restore SQL/MX objects. You can also save database creation and loading scripts in OBEY
command files or write an automated program to handle TMF and backup and restore
operations.
Use Backup and Restore 2 to back up to tape and restore to disk SQL/MX objects, OSS
program files, and other components, as required to properly recover your database. Restore
2 uses BRCOM, the command-line user interface from which you enter and manage BACKUP
and RESTORE commands for SQL/MX objects and OSS objects. For more information about
the BRCOM command syntax, see the Backup and Restore 2 Manual.
18 Introduction to SQL/MX Database Management