SQL/MP Version Management Guide

Version Compatibility for SQL Programs
Compaq NonStop™ SQL/MP Version Management Guide—429833-001
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SQL Execution in a Mixed Version Network
The SQL compiler does not select parallel execution as a plan for query execution if the
queried object is on a node using version 1 SQL software; the compiler does not select
hash joins if the queried object is on a node using version 2 software.
Figure 7-4
illustrates parallel execution when these query execution techniques are not
supported by all the nodes in a mixed version network.
SQL Execution in a Mixed Version Network
A version 300 or newer SQL executor can execute any SQL program on any node
whose format version is 1, 2, 300, or newer. Any attempt to execute an SQL program
whose format version is newer than the version of the SQL executor results in a version
error. Program execution is determined by the format version of the program, which in
turn is determined by the version of the SQL compiler that compiled the program.
A version 300 or newer SQL executor executes an SQL program whose format version
is 2 as if the executor were also version 2. Similarly, a version 300 or newer SQL
executor executes a program whose format version is 1 as if the executor were also
Figure 7-4. Parallel Execution in a Mixed Version Network
Node Running
Version 315 NonStop SQL/MP
Table A Table B Table C
SQL
Compiler
No Parallel Execution No Hash Joins
Node Running
Version 315 NonStop SQL/MP
Node Running
Version 1 NonStop SQL
Node Running
Version 2 NonStop SQL
Parallel Execution
and Hash Joins
SQL compiler does not use parallel execution or hash joins.
1
1 1
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