OpenEdge Data Management: DataServer for Microsoft SQL Server

Tuning your environment with the –Dsrv startup parameter
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;
The connection string is separated from the option by a comma (,) and ends with a semicolon (;).
Use the PRGRS_CONNECT option in the following cases:
• To connect to a data source whose name is not allowed by OpenEdge; for example, a name
that includes blank spaces, ampersands (&), commas (,), and/or carets (^). In the
connection string, pass the following characters rather than the unallowed characters. The
driver resolves the passed characters to the unallowed character:
– Pass the ampersand (&) character as two ampersand (&&) characters
– Pass the caret (^) character as two caret (^^) characters
– Pass the blank space character as an ampersand and a caret (&^)
– Pass the comma (,) character as a caret and ampersand (^&)
• To establish complex connections that require more than the Physical Database Name
(-db), User ID (-U), and Password (-P) parameters. In all cases, the values must not be
space delimited and must be passed in a single connection string.
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