JDBC Type 4 Driver Programmer's Reference for SQL/MX Release 3.2 (H06.25+, J06.14+)

7 Module File Caching (MFC)

• “MFC Overview” (page 69)

• “MFC Design” (page 69)

• “Configuring MFC” (page 69)

• “Enabling MFC” (page 69)

• “MFC Usage Scenarios” (page 70)

• “MFC Tuning Recommendations” (page 70)

• “MFC Limitations” (page 71)

MFC Overview

Applications that use the JDBC Type 4 driver might encounter repeated SQL compiles while using

statements and PreparedStatements. To overcome this issue, a driver side Most Frequently

Used (MFU) cache is used. However, the current design of the driver side cache consumes large

amount of memory. The size of the MXOSRVR process memory is directly proportional to the size

of the driver side cache configured through the maxStatements property. Higher

maxStatements value (driver side cache size) can breach the MXOSRVR process memory limit

of 2 GB on the NonStop platform.

The Module File Caching (MFC) feature shares the statement and PreparedStatement plans

among the NonStop SQL/MX database connections. The MFC helps in reducing the SQL compilation

time during JDBC or ODBC application's steady state, 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.

MFC Design

For information on the MFC design, see the HP NonStop Connectivity Service Manual for SQL/MX

Release 3.2.

Configuring MFC

For information on configuring MFC, see the HP NonStop Connectivity Service Manual for SQL/MX

Release 3.2.

Enabling MFC

MFC for the JDBC Type 4 driver is enabled through the MXCS configuration, and SQL modules

are created automatically when statements are prepared. A client program can explicitly turn OFF

MFC if modules are not required.

The following property is required to use MFC in an application that uses the JDBC Type 4 driver:

enableMFC

To disable MFC, the value of this property must be set to OFF. For example:

-Dt4sqlmx.enableMFC = OFF.

In the JDBC Type 4 driver, the default value is ON.

MFC Overview 69