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Postings from March 2008
On 14.03.2008 09:46, Martin Evans wrote: > Alexander Foken wrote: >> There is one annoyance with SQL server: You can't have more than one >> "active" statement, i.e. a statement that is executing but not yet >> finished, per connection. This is a limitation of the SQL server >> protocol, not a DBI limitation. Other databases, like Oracle and the >> free PostgreSQL, can handle at least a sufficiently large number of >> parallel active statements. For the MS SQL Server, you have to use >> several distinct connections if you need parallel active statements. > > That is no longer true Alexander: > > MARS. Multiple Active Result Sets (MARS), enables your applications to > have more than one pending request per connection, and, in particular > to have more than one default result set open per connection. The MARS > feature removes the restriction present in earlier versions of SQL > Server in which an open default result set blocks the driver from > sending requests to the server until the entire result set is consumed. Glad to see that this particular restriction is gone. I once had to port one of my projects from Oracle to SQL Server 8, when that was the most recent version. SQL Server 8 did not have that feature or it was so well hidden that I did not found it in days of research. That project is also used with newer SQL Server versions, SQL Server 2003 is the latest version used in a production environment I know of. For all SQL Server versions, the project uses the multi-connection hack. Switching to a single connection with multiple parallel statements would be a great improvement. Is it possible to use that feature with DBD::ODBC? What are the minimum required versions of DBI, DBD::ODBC, SQL Server? Where and how is MARS enabled? Alexander -- Alexander Foken mailto:alexander@foken.de http://www.foken.de/alexander/Thread Previous | Thread Next