MX 2.x)

Starting, Configuring, and Managing MXCS

HP NonStop SQL/MX Connectivity Service Manual—524944-008

3-27

Module File Caching (MFC)

Before the H06.18/J06.07 RVU, the ODBC/MX driver did not cache the NonStop

SQL/MX prepared statements. As a result, applications recompiled the same SQL/MX

statements, causing higher host utilization, which could lead to worse perceived

performance of the ODBC client application.

The Module File Caching (MFC) feature shares the SQL/MX prepared statement plans

among the SQL/MX database connections. It helps in reducing the SQL/MX

compilation time during the steady state of the JDBC or ODBC application, thereby

reducing resource consumption.

Design of MFC

MFC shares static module files created from dynamic queries using SQL/MX tools,

across MXOSRVR or SQL/MX connections.

MFC uses disk files on the NonStop Open System Services file system for storing the

compiled SQL/MX prepared statement plans. When the application prepares a query,

MFC checks for an existing plan that matches the query. If a plan exists, it is loaded

from the disk thereby eliminating the requirement of SQL compilation of the query.

If a plan for an incoming PREPARE statement for a query is not found on the disk, a

plan is created as follows:

1. The incoming query is compiled as any other SQL/MX prepared statement.

2. After successful completion of the SQL/MX prepared statement, a plan is

generated and stored in the directory specified in the

compiled_module_location attribute of SQL/MX. Synchronization issues are

handled using temporary lock files.

Use an MFC management script for maintaining the compiled module plans on the

NonStop server. The MFC management script is described under Managing MFC on

page 3-29.

Configuring MFC

To configure the module file caching feature using the MXCS subsystem, perform the

following steps:

1. Enter the MXCS subsystem through MXCI:

mode mxcs;

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.