JDBC Type 2 Driver Programmer's Reference for SQL/MX Release 3.2.1 (H06.26+, J06.15+)

6 Module File Caching
The Module File Caching (MFC) feature shares the SQL/MX prepared statement plans among the
JDBC/MX T2 database connections and JVM processes. It helps in reducing the SQL/MX compilation
time during the steady state of the JDBC/MX T2 application, thereby reducing resource consumption.
NOTE: Module File Caching is supported only on systems running J06.07 and later J-series RVUs,
and H06.18 and later H-series RVUs.
The topics discussed in this chapter are:
• “What is New” (page 58)
• “Design of MFC” (page 58)
• “Enabling MFC” (page 58)
• “Limitations of MFC” (page 58)
• “Troubleshooting MFC” (page 59)
What is New
Starting with SQL/MX Release 3.2, MFC supports the BigNum data type in parameterized queries.
Design of MFC
For information on the MFC design, see the HP NonStop SQL/MX Connectivity Service Manual.
Enabling MFC
The following are the two new properties which are required for using MFC in an application that
uses the JDBC/MX T2 Driver.
• enableMFC Property:
To enable MFC, the value of this property must be set to ON.
• compiledModuleLocation Property:
The value for this property must be a valid directory name. For example: /usr/temp. This
is the location where the intermediary files such as *.mdf for MFC are generated.
Both these properties must be set to enable MFC.
Limitations of MFC
• MFC cache should be used only on production systems. It should not be used on development
or User Acceptance Testing (UAT) systems where SQL/MX undergoes changes.
• It does not handle session-specific SQL/MX Control Query Defaults (CQD) and SQL/MX
Control Query Shape (CQS).
• HP recommends that when using with MFC, set the CQD in SQL/MX for disabling the
auto-recompilation feature of SQL/MX. The CQD for disabling the auto-recompilation is
"CONTROL QUERY DEFAULT RECOMPILATION_WARNINGS 'ON'". This ensures that
automatic recompilations are avoided due to changes in SQL/MX objects because the plans
are generated in the module file. The application will receive an SQL/MX exception if there
is an auto-recompilation required for the query. You must clean the stale module files before
continuing with the application. For more information on the CQD, see the HP NonStop
SQL/MX Release 3.2.1 Reference Manual.
• For lightweight queries, MFC performs only marginally better than the SQL/MX compile.
58 Module File Caching