Error Messages (I)

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Invalid Descriptor Index (0) errors and the DeferLongFetch MT DSN setting with MS-SQLServer

When deferred fetching is used to fetch long data using our Microsoft SQL Server Agent,then any columns containing long data need to be the last columns in the select list as we use the SQLGetData API call on those columns.

As the MT (4.x) ODBC driver fetches the data in this fashion, an error may sometimes occur because the Agent will try to fetch the data from the next sequential column in the select list, while the Defer Fetching feature has actually skipped that column over in the BindCol/Fetch calls. This behavior is a restriction imposed by the SQL Server database and not a bug in the driver per se.

In general terms we would advise you that in order to benefit from the deferred fetching feature in our agent, you should put columns containing long data at the end of the select list in your query.

Evidence

ODBC Trace
Request Broker Log File
Request Broker Trace]
Database Agent Version String