OpenEdge Data Management: DataServer for Microsoft SQL Server

Additional Features to Enhance DataServer Performance
4–6
Fast Forward-Only cursors
In the event that a firehose cursor cannot be used, the DataServer attempts to use a Fast
Forward-Only (FFO) cursor with Auto-Fetch and Auto-Close attributes. FFO cursors are the
server-side equivalent of firehose cursors. FFO cursors have special optimization characteristics
that distinguish them from other server-side cursors. They require a minimum of server-side
resources and are capable of minimizing round trips to the server. FFO cursors are an extension
to the ODBC specification and are unique to ODBC drivers that conform to Microsoft SQL
Server driver requirements. The Auto-Fetch attribute directs the server to return the initial block
of results in the same network message that provided the SQL request to be executed by the
server. The Auto-close attribute directs the server to automatically close the cursor on the same
round trip in which the last query result is received by the client.
Note: Result sets that include text or image columns cause an implicit conversion from an
FFO to a dynamic cursor type. These are columns that translate through ODBC to SQL
LONGVARCHAR and LONGVARBINARY data types.
Monitoring cursor and connection use
Monitor the use of your managed connections to tune the number of connections you allocate.
If you regularly exceed your allocation, consider increasing the number of managed
connections. If you never use your total allocation, consider decreasing the number of managed
connections.
You can monitor connections either through using OpenEdge logging or by enabling logging
using the “-Dsrv qt_debug,cursor” switch.
Note: The OpenEdge logging infrastructure offers more extensive reporting capabilities than
qt_debug. For details on enhanced logging, see
Monitoring connections with qt_debug
The DataServer log contains messages indicating the status of connections. At startup, the
number of managed connections initialized is written to the log file. If connections are rejected,
this is also logged. If a connection from the ODBC connection pool cannot be reused, the ODBC
driver issues the message DEAD Connection which is written to the log file.
At the end of a session, the DataServer writes summary information about cursor use. The
summary contains the following information:
• Needed connections — The number of connections actually used during a session
• Peak connections — The maximum number of connections used simultaneously during
a session
When debug logging is enabled with the “-Dsrv qt_debug,cursor” switch, a summary of
connection activity is written to the log file. This summary contains:
• Number of connections (defaults to 5)
• Number of peak connections (defaults to 5)
• Highest connection value