NonStop SQL/MP Reference Manual

Table Of Contents
NonStop SQL/MP Reference Manual142115
M-8
Considerations—MODIFY CATALOG
CHECKONLY
specifies that the catalog tables specified in target-spec should be checked to
see if they contain node names that match the criteria specified in the REPLACE
clause. No catalog tables are changed. The CHECKONLY option lets you estimate
the effect of running the MODIFY CATALOG command before actually modifying
the catalog tables.
Considerations—MODIFY CATALOG
Authorization requirements
You must be logged on as the super ID to execute a MODIFY CATALOG command
unless you specify the CHECKONLY option. If you specify the CHECKONLY
option, you must have authority to read the catalogs.
TMF considerations
SQL uses the TMF subsystem to protect the integrity of the database during the
MODIFY operation. MODIFY CATALOG commands are not allowed inside a user-
defined transaction.
One system-defined transaction is used for each set of catalog tables modified. If an
error occurs while MODIFY CATALOG is modifying a catalog table, the changes
made to that catalog table and all other tables in the same catalog are backed out.
However, changes that have been made to other catalogs during the same instance of
the MODIFY CATALOG command are not backed out. Thus, for one set of catalog
tables, either the node name will be changed in all of the tables in the set or it will
not be changed in any of the tables in the set.
The MODIFY CATALOG command is one of a set of commands that uses the
MODIFY DICTIONARY utility. The other related commands are MODIFY
LABEL Command on page M-11 (to change node numbers in file labels) and
MODIFY REGISTER Command
on page M-22 (to register user- defined catalogs in
the local system catalog).
Multiple MODIFY commands (including LABEL, CATALOG, and REGISTER
commands) can be executed concurrently on the same node as long as each
command is processing a different set of files or catalogs. For example, if the node
number is changed on a node that has an SQL database spread out over five
volumes, five MODIFY LABEL commands can be started concurrently, each
specifying a different volume to be modified. Note that in such a case, because the
node name did not change, it would not be necessary to execute any MODIFY
CATALOG commands.
Before requesting a MODIFY CATALOG operation for a catalog, do a MODIFY
LABEL operation on all catalog tables in the catalog.
MODIFY CATALOG locks one catalog table at a time. The file labels of the catalog
tables are not locked. Do not request DDL or update operations until the node names
are modified, including operations on partitions and on dependent objects on remote
nodes.
The MODIFY DICTIONARY utility does not handle the following: