SQL/MX 2.x Installation and Management Guide (G06.24+, H06.03+)

Reorganizing SQL/MX Tables and Maintaining Data
HP NonStop SQL/MX Installation and Management Guide—523723-004
10-5
DDL Lock Considerations for MODIFY, import, DUP,
and PURGEDATA
If you want to keep the same RATE and SLACK values when you restart the
reorganization process, enter the FUP RELOAD command without the RATE and
SLACK parameters:
FUP
- RELOAD $DATA08.ZSDAWVHH.J8MGRZ00
After a FUP RELOAD operation has been suspended and you want to start this
operation completely over again, enter the FUP RELOAD command with the NEW
option:
FUP
- RELOAD $DATA08.ZSDAWVHH.J8MGRZ00, NEW, RATE 30, SLACK 50
In the FUP RELOAD command, the NEW option is necessary only when restarting a
RELOAD operation over again from the beginning, following a RELOAD suspension.
DDL Lock Considerations for MODIFY, import,
DUP, and PURGEDATA
A utility operation usually occurs over several TMF transactions, time during which
other operations might attempt to run. However, operations that change metadata and
label information for the same table or index, including DDL requests and other utility
operations, are considered structure changing operations. To prevent other structure
changing operations from running before it completes, a running utility obtains and
holds a DDL lock for the duration of its execution.
The DDL lock persists across the boundaries of the TMF transactions that compose
the utility operation. The DDL lock signifies that a structure change is in progress for a
given table or one of its indexes. Other structure changing operations cannot be
performed until the operation that holds the DDL lock completes. DDL locks are usually
obtained for utilities that run in multiple operations and therefore require compensating
work to recover the utility operations.
The utility request informs NonStop SQL/MX that it is running, performs commands
over as many TMF transactions as necessary, then informs NonStop SQL/MX that the
operation has completed.
Structure changing operations include:
•
A DDL operation that changes the definition of the object (for example, alter table,
add column, or create index)
•
A DDL operation on a dependent object (for example, an index, constraint, or
trigger)
•
A utility operation that changes the definition of the object
•
A utility operation on a dependent object
These SQL/MX utilities use DDL locks:
•
MODIFY. See Using MODIFY to Manage Table and Index Partitions on page 10-9.