Progress
Version 9
Product Update Bulletin
Progress Version 9.1C DataServer For ODBC
The Progress Version 9.1C DataServer for ODBC had enhancements and new features of which the following -Dsrv startup parameter is documented here.
Query Result Order: The PRGRS_ALWAYS_INDEX Option
The default value for the PRGRS_ALWAYS_INDEX option is 1 or ON. For the ODBC DataServer, if the driver is capable of and is configured to allow its ODBC cursors to be preserved across transaction boundaries, then PRGRS_ALWAYS_INDEX can be set to zero. If cursor preservation is not allowed for the specified driver and/or not allowed with the data source to which the driver is connected, then the PRGRS_ALWAYS_INDEX setting is ignored.
Some queries can gain a performance advantage when the result set from the query does not use an index to order the results. 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). See documentation for your ODBC data source and driver to determine if cursor preservation is possible. When this option is off and the user does not specify an index or BY clause for the results of their 4GL statement and the particular 4GL being executed does not require scrolling capability in the Progress 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. Regardless of whether or not an ORDER BY clause is used, the DataServer has no control over the index utilized by the data source.
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