SQL/MX 2.x Installation and Management Guide (H06.10+, J06.03+)

Managing an SQL/MX Distributed Database
HP NonStop SQL/MX Installation and Management Guide—544536-007
13-25
Managing Mixed Versions of NonStop SQL/MX
the operating system release imposes compatibility issues on the database. For
more information about versioning issues, see The SQL/MX Environment on
page 1-11.
•
Communication to a node is lost. Nodes can become unavailable for a variety of
reasons. For planned outages, you should systematically make inactive all network
transactions to the affected node before taking it offline. For unplanned outages,
transactions are rolled back by NonStop SQL/MX as errors and are reported as
communication problems. Sometimes, you might need to use one of the TMF
interfaces (for example, TMFCOM) to manually back out the transactions. After
communications are restored, transactions can resume and proceed normally.
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Recovery takes place for a system crash on a single node. If a node crashes, it
can be recovered by using a TMF recovery method. HP recommends that you
initiate the START TMF, TRANSACTIONS OFF operation at the crashed node.
This approach enables TMF to resolve any network-distributed transactions active
at the time of the crash and to attempt volume recovery.
Keeping TRANSACTIONS OFF in effect during this procedure enables the function
to complete successfully, before new transactions are introduced to the database.
TMF does not allow new transactions to start before START TMF is completed
because new transactions require network transaction resolution and volume
recovery. Another important reason for keeping TRANSACTIONS OFF is to
provide the system administrator time for additional recovery operations, as
needed, before the applications can start transaction activity. For additional
information, see the TMF Planning and Configuration Guide.
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A number of situations can cause severe problems with the consistency of an
SQL/MX database. Various techniques can resolve these problems. You should
not, however, attempt these operations without help from your service provider:
°
Recover a node with distributed objects by using the TIME option of TMF. This
procedure can cause an inconsistent database.
°
Perform a RESTORE of objects on a node, such that the restored objects
would not be consistent with the rest of the database.
°
Use the MXTOOL GOAWAY utility on portions of a network database.This
procedure can leave unresolvable references in other metadata.
If a situation arises that you think might affect the network-distributed SQL/MX
database, contact your service provider for additional information.
Managing Mixed Versions of NonStop SQL/MX
SQL/MX Release 2.x does not support interoperability with SQL/MX Release 1.8 in a
distributed database environment. You cannot perform queries, through embedded
SQL or dynamic SQL, from a node running SQL/MX Release 2.x on a node running
SQL/MX Release 1.8, and vice versa. You can, however, use SQL/MX Release 1.8
query plans and modules that have been compiled on an SQL/MX Release 2.x node,