RDF/IMP and IMPX System Management Manual (RDF 1.4+)

Managing RDF
HP NonStop RDF/IMP and IMPX System Management Manual—524388-001
5-27
RDF and SQL DDL Operations
RDF and SQL DDL Operations
When certain Data Definition Language (DDL) operations are performed on SQL/MP
tables protected by RDF, applications that depend on these operations are briefly
denied access to the database while the DDL operations are in progress. These
periods of unavailability, commonly called outages, end when the DDL operation
completes.
When you perform SQL/MP DDL operations such as the following, you can either
include or omit the WITH SHARED ACCESS option:
•
The CREATE INDEX statement, used when creating an index on a table
•
The MOVE clause of the ALTER TABLE or ALTER INDEX statement, used when
moving, splitting, or merging disk file partitions, or when moving boundaries within
partitions
To determine all of the SQL/MP DDL operations that can be performed WITH SHARED
ACCESS, refer to the HP NonStop SQL/MP Reference Manual.
When included, the WITH SHARED ACCESS option specifies that the DDL operation
is to allow concurrent read-write Data Manipulation Language (DML) access and read-
only utility access to the objects on which it operates during all but the final phase of
the operation. For this reason, operations specifying the WITH SHARED ACCESS
option are sometimes referred to as Online DDL operations.
The only operations that must be performed WITH SHARED ACCESS are merge
partitions and move boundaries. It is recommended that you perform all other
operations with non-shared access.
Performing Non-Shared Access DDL Operations
For DDL operations that do not include the WITH SHARED ACCESS option, you can
minimize outage for the primary system applications as follows:
1. Stop the applications that use the database being protected by RDF.
2. Stop TMF on the primary system.
3. Wait for RDF to stop.
4. Start TMF.
5. Start RDF with updating disabled.
6. Perform the DDL operations on the primary system.
7. Restart the applications.
8. Perform the same DDL operations on the backup system.
9. Issue an RDFCOM START UPDATE command.