MARS - Multiple Active Result Sets
Multiple Active Result Sets - MARS In a nutshell, it is the ability to have more than one pending request under a given SQL Server connection. For most cases this will directly translate to the ability to have more than one default result set (firehose cursor) outstanding while other operations can execute within the same session. It is probably as important to delimit what MARS is not: Parallel execution: Though MARS enables more than one request to be submitted under the same connection, this does not imply that they will be executed in parallel inside the server. MARS will multiplex execution threads between outstanding requests in the connection, interleaving at well defined points. Cursor replacement: As described earlier, there are some scenarios where cursors represented a suitable workaround for a lack of MARS; it may be valid to migrate those scenarios to use MARS. However, this does not imply that all current usages of cursors should be moved to MARS. By default, all o...