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Postings from March 2008
Alexander Foken wrote: > 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 I believe this came in around SQL Server 2005. You can set it in some registry setting! or in the connection string with "MARS_Connection=Yes". You can find detailed info about MARS on the MS web site including some things to watch out for when using MARS and transactions. You will need a 2005 ODBC Driver and the best one to use is the new "SQL Native Client" (mine is version 2005.90.1399.00). As you can set it in the connection string you can use it from DBD::ODBC using something like: set DBI_DSN=dbi:ODBC:DSN=mydsn;MARS_Connection=Yes If you do this and run the 20SQLServer test you'll find the multiple active statement tests fail because they check you cannot use MAS and you can now. Martin -- Martin J. Evans Easysoft Limited http://www.easysoft.comThread Previous | Thread Next