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HP NonStop JDBC Type 4 Driver
Performance Tuning Guide for Version 1.0
• Turn off autocommit when possible (the default is on). All transaction levels
might operate faster with autocommit turned off, although using this setting
requires you to code commits. Leave autocommit on for single statements.
• Avoid repeatedly calling expensive database query functions such as:
getBestRowIdentifier, getColumns, getCrossReference, get ExportedKeys,
getImportedKeys, getPrimaryKeys, getTables, or getVersionColumns. If possible,
call these functions once, and cache the returned data.
• Use the type-correct get() method, rather than getObject().
• Always close Statement and ResultSet objects as soon as possible.
• When using connection pooling, avoid setting the connection’s catalog, schema,
transaction isolation, and autocommit attributes programmatically at run time. Set
these values appropriately with your data source properties. Note: theses
properties are not reset when a connection is pooled.
• Use “BOWSE” (READ UNCOMMITTED) access on SQL statements when
possible.
• Use the Statement.setFetchSize() and ResultSet.setFetchSize() methods to tailor
the number of rows pre-fetched to reduce the number of messages sent to the
database.
• Use UNICODE character columns in your database to avoid implicit conversion
between the database encoding and Java’s UNICODE String encoding.
4 SQL/MX Connectivity Services Tuning Tips
• Safeguard supports multiple alias and password pairs for a single Guardian user
name. Using these aliases or password pairs can improve performance because
object caching reuses the underlying user name. You can set up an anonymous
log-in capability by adding a user name such as guest with no password; then map
this user name to a user group that has limited access to the SQL objects.
• Use a non-default server data source when making a connection, and configure
the data source to optimize performance for your environment. See the
“serverDataSource” property in the NonStop JDBC Type 4 Driver Programmer’s
Reference manual, and “server data source” in the SQL/MX Connectivity Service
Manual.
• See the SQL/MX Connectivity Service Manual for additional information.
• Tune the process priority of the server’s operating system. See the Mixed
Workload Design Priority Guidelines white paper in the NonStop Technical
Library for additional information.
• Use the “CONTROL TABLE
control table statement to tune the priority for subsequent file system requests to
the Data Manager (DAM). See the SQL/MX Reference Manual for additional
information.
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Hewlett-Packard Company — 529619-002
April 8, 2005
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Ordinateurs - HP NonStop L-Series (120.04 kb)