JDBC Type 4 Driver 3.0 Programmer's Reference (SQL/MX 3.x)

MFC combined with limited driver side cache is recommended for JDBC T4 applications, where
the number of distinct queries is not known or not fixed.
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MFC Tuning Recommendations
When the number of connections required to be configured per processor is high in number (for example,
more than 20 connections per processor), use MFC for less memory utilization.
If an application has a small number of OLTP queries (such as, JOE) where there is no memory pressure
and memory pressure is heavy in execute() and fetch(), the MFC performance result will be close
to that of the T4 driver cache with MFC consuming lesser memory. In such applications, when a small
number of connections are configured per processor, configure only the JDBC T4 driver cache because
there is no major difference between MFC and the T4 driver cache.
For applications with small number of queries, Driver Side Cache (DSC) provides better response time.
For applications that have a large number of queries, use a combination of DSC and MFC, which results
in better memory usage and similar response time of DSC. For typical applications, find the number of
most frequently used statements and configure them as DSC and the rest as MFC. If the most frequently
used statements number is not known, it is recommended that you configure a number closer to 60% of
total queries in the application.
For example, if the application has 1000 unique queries, configure DSC
(t4sqlmx.maxStatements) to 600. The applications with more number of queries configured in the
DSC, cause memory swap. Therefore, reduce the DSC number and increase the queries in the MFC.
The JDBC/T4 driver, in memory, caches the most frequently used statements. The MXOSRVR, on the
NonStop host, caches the infrequent queries using MFC.
MFC Limitations
MFC is not a replacement for the JDBC T4 Driver Side Cache (DSC); the JDBC T4 driver side cache has
a better response time than MFC.
For more information on MFC limitations, see the HP NonStop SQL/MX Connectivity Service Manual.
Statement Caching
If the statement caching feature is enabled, the JDBC T4 driver will cache the SQL statements, which use
the scalar functions with a higher number so that the statements are not removed from the cache. For
information on statement caching, see maxStatements Property.
If the statement caching feature is not enabled or if there is no place in the JDBC T4 driver cache and the
SQL statement to be prepared uses a scalar function, the JDBC T4 driver will not permit the server side
to use MFC while preparing this statement. For information on MFC limitations, see the HP NonStop
SQL/MX Connectivity Service Manual. The scalar functions that are not supported by MFC are in