JDBC Type 4 Driver Programmer's Reference for SQL/MX Release 3.2.1

NOTE: There is no need to change any data source configuration settings to disable MFC.
For more information on MFC, see:
• Module File Cache for NonStop SQL/MX at http://h20195.www2.hp.com/V2/
GetDocument.aspx?docname=4AA3-8922ENW&cc=us&lc=en
• Distributed transactions (XA) on HP NonStop systems at http://h20195.www2.hp.com/V2/
GetPDF.aspx/4AA3-8405ENW.pdf
MFC Usage Scenarios
The benefits of lower processor utilization and the reduction in subsequent compile times mentioned
in this section are applicable on the NonStop Server.
• JDBC T4 applications using java.sql.Connection.Statement() and
java.sql.Connection.prepareStatement() have the benefit of lower processor
utilization and better response time.
• JDBC T4 applications using complex queries through prepare calls, have higher benefit of
lower processor utilization, lower memory consumption, and better response time. For example,
Hibernate generated queries.
• JDBC T4 applications with higher driver-side cache size can benefit from lower memory
utilization by using the combination of MFC and a lower driver-side MFU cache.
For example, an application with t4sqlmx.maxStatements=1000 can benefit by changing
to t4sqlmx.maxStatements=600 and MFC.
In this example, all statements are cached in MFC and the most frequently used statements
are cached in the driver side MFU cache.
• JDBC T4 applications, which have large number of statements that are SQL compiled at the
startup, can benefit from reduced (re-) startup time by using the MFC feature. In situations,
where servers are configured for automatic restart, the startup time is reduced.
JDBC T4 applications experiencing high memory swapping can benefit from reducing the
driver side cache and enabling MFC. Reduce the driver side cache and enable MFC in the
scenarios, where the MXOSRVR process exceeds 1 GB in size frequently.
• For JDBC T4 applications where the large number of MXOSRVR processes is configured per
processor, enable MFC to reduce swapping. The other option is to increase the physical
memory per processor to reduce swapping.
• 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.
MFC Tuning Recommendations
When the number of connections required to be configured per processor is more (for example,
more than 20 connections per processor), use MFC for less memory utilization.
If an application has a small number of OLTP queries 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 Usage Scenarios 71