NonStop JMS User's Manual (H06.03+, J06.03+, NonStop JMS 3.0+)

NSJMS Installation and Configuration for TNS/R
NonStop Server for Java Message Service User’s Manual—522356-006
2-18
Adding a Message-Table Dummy Record
After completion of the previous SQLCI ALTER TABLE command, the table has two
partitions that have these starting destination ID values:
An existing partition within a message table that has three partitions is split. Before the
split operation, the message table has three partitions that have these starting
destination ID values:
By using this SQLCI ALTER TABLE command, $VOL1 splits into two partitions,
resulting in the new partition residing on $VOL4. Destinations that have ID values
greater than or equal to 5000 but less than the starting destination value for $VOL2
(10000) are relocated to $VOL4.
After completion of the above SQLCI ALTER TABLE command, the message table has
four partitions that have these starting destination ID values:
Adding a Message-Table Dummy Record
You can add a dummy record to a message table when you create a new partition for a
message table. A dummy record is a record that is never deleted from a message
table. Dummy records improve performance when tables often transition from the
empty to non-empty condition by avoiding the overhead of collapsing and expanding a
message table. A dummy record is assigned a destination ID value that is never
assigned as a destination.
Partition Location Starting Destination ID
$VOL1 0
$VOL2 10000
Partition Location Starting Destination ID
$VOL1 0
$VOL2 10000
$VOL3 20000
SQLCI>> ALTER TABLE $VOL1.NSJMS.MESSAGE
+> PARTONLY MOVE FROM KEY (5000,0) TO $VOL4.NSJMS.MESSAGE
+> CATALOG $VOL1.NSJMS
+> EXTENT (1000,200);
--- SQL OPERATION COMPLETE
Partition Location Starting Destination ID
$VOL1 0
$VOL4 5000
$VOL2 10000
$VOL3 20000