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

Introduction to SQL/MX Database Management
HP NonStop SQL/MX Installation and Management Guide—523723-004
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Versioning Guidelines for Release 2.1 and Release
2.0
Versioning Guidelines for Release 2.1 and Release 2.0
Query Execution Plans
•
You cannot perform queries—through embedded SQL or dynamic SQL—between
a node running Release 2.1 or Release 2.0 and a node running Release 1.8.
However, these nodes can use Release 1.8 query plans and modules that have
been compiled on a Release 1.8 node, as these are within the range of the earliest
supported plan version (800).
•
A Release 2.1 compiler generates a query execution plan version of 1400 except
in these cases, where the plan version is 1200:
°
The plan references objects on one or more Release 2.0 nodes.
°
The plan uses prototyping.
°
The query execution plans reside in a system module. It is true that the actual
plan content might be the same, but the version will not.
•
Query execution plans for database objects on a Release 2.0 node always have a
plan version of 1200.
•
A query execution plan on a Release 2.1 node or Release 2.0 node can reference
objects that are distributed across both Release 2.1 and Release 2.0 nodes.
However, the query execution plans for these objects will be 1200.
•
The query execution plans for applications compiled on a Release 2.0 system have
a plan version of 1200, even if the referenced database objects exist on Release
2.1 nodes.
•
Release 2.1 introduces faster expressions for some types of queries than Release
2.0. Therefore, some Release 2.1 query execution plans will show better
performance than comparable Release 2.0 plans. For information about these
performance enhancements, see the SQL/MX Query Guide.
•
Compiling an application on a Release 2.1 system that refers to objects on
Release 2.0 nodes might produce query execution plans that do not have the
performance enhancements of Release 2.1. If you want to obtain these
performance enhancements throughout a distributed database, migrate all
referenced Release 2.0 nodes to Release 2.1.
•
The SQL/MX compiler does not manage multiple plan versions. All plans
generated by a compiler get a plan version equal to that compiler’s current plan
version.
Falling Back From Release 2.1 to Release 2.0
•
User modules on a Release 2.1 system have a module version of 1400. User
modules on a Release 2.0 system have a module version of 1200. After you fall