Availability Guide for Change Management

Making Application Subsystem Changes Online
Availability Guide for Change Management–125506
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NonStop SQL/MP Changes You Can Perform Online
that reference the objects, providing the SQL object has its SIMILARITY CHECK
option set to ENABLE.
Two objects are considered to be similar if the same execution plan can be used to
access either object. An operable plan is semantically correct and can execute correctly
without SQL recompilation (although it might not be optimal) while an inoperable plan
must be recompiled to execute correctly.
Moving a Database or Database Program
You might need to move a database or database objects when new equipment is added,
when a database and application programs are moved from one system to another, or to
enhance performance.
Changing the location of your database will have some impact on application
availability. For certain databases, availability will be very high; for other databases, it
will be lower.
When you move a database program, it might need to be recompiled. Recompilation
may be necessary even if the program was previously compiled on a different system. In
certain situations, you can avoid recompiling moved programs and the associated impact
on application availability by using the following compiler options:
•
REGISTERONLY—This option directs the SQL compiler to register a previously
compiled program in a specific catalog without recompiling any SQL statements in
the program. You can use this option to install a program in a catalog after you have
compiled the program with the SQL compiler and moved the program. The
REGISTERONLY is much faster than explicitly recompiling the entire program.
•
NOREGISTER—This option directs the SQL compiler to compile a program
without registering the program in a catalog. You can then move the program using
a SQLCI DUP command or the BACKUP and RESTORE programs. After the
move, you can run the program without recompiling or registering it in a catalog.
The COMPILE and CHECK compiler options can be used to selectively recompile plans
in a program and reduce the time of recompilations. Refer to “Reorganizing a
Database” for information about these options.
Changing the Node Name or Node Number
The following types of operations cause the node name or number to be changed but do
not automatically update the NonStop SQL/MP catalogs and file information:
•
Cold loading the node with a different node name or number
•
Restoring a volume-mode backup on a different node
•
Physically moving disks from one node to another
To update the node number or node name, use the NonStop SQL/MP MODIFY
[DICTIONARY] commands. Note, however, that these commands do not update node
names or numbers that are stored as data in the database; they only affect node names in
the SQL catalog or node numbers in file labels of SQL objects and object programs.