OpenEdge Data Management: DataServer for Microsoft SQL Server

Using MS SQL Server and DataServer options
ODBC options
This section provides information on using various ODBC and DataServer options.
Transaction Management: the AUTOCOMMIT option
To avoid using the MS SQL Server transaction manager, specify -Dsrv AUTOCOMMIT,1.
This option exercises the OpenEdge client’s local before-image mechanism to manage
transactions. This creates a transaction from each SQL statement that the DataServer
issues. OpenEdge emulates the logical transaction on behalf of the application using
the local before-image mechanism. This connection technique is useful in
multi-database applications.
Note: OpenEdge does not guarantee crash recovery when it uses the local
before-image mechanism to emulate transactions.
Query Result Order—the PRGRS_ALWAYS_INDEX option
Some queries can gain a performance advantage when the result set from the query
does not use an index to order the results. In older versions of the DataServer for
Microsoft SQL Server, results sets were always indexed because queries and their
results were gathered in segments with new cursors being generated for each query
segment. However, most advanced drivers and data sources now allow a single cursor
to be retained for the life of a given query, even across a transaction boundary. Drivers
that can preserve cursors are allowed to execute unindexed queries if the
PRGRS_ALWAYS_INDEX option is set to 0 (off). When this option is off and the user does
not specify an index or BY clause for the results of their ABL statement and the
particular ABL being executed does not require scrolling capability in the OpenEdge
client, the query result will remain unindexed by the DataServer.
Note: In an unindexed query, the DataServer will not send an ORDER BY clause to the
data source. However, the DataServer has no control over whether or not the
actual data source utilizes an index in order to generate a result set.
Concurrent query execution—the PRGRS_CACHE_CONN option
It is possible to run read-only queries in separate connections through the driver to the
MS SQL Server. Opening a separate connection to run a query or stored procedure
can provide better performance, although this is not guaranteed. Having too many
open connections can degrade performance. The PRGRS_CACHE_CONN option allows
you to set a limit for the maximum number of server connections available in the
DataServer session. If the session attempts to exceed the maximum threshold, the
session will need to wait for an existing connection to complete before an additional
connection can be made.
Connection problems—the PRGRS_CONNECT option
The PRGRS_CONNECT option allows you to pass ODBC-specific information to the ODBC
driver. This option has the following syntax:
Syntax
-Dsrv PRGRS_CONNECT,connection-string;
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