Difference Between Master Detail relation ship and Join

[sunny bachan prasad]

Hi Guru,
Is master detail in report studio is same as the join in sql. Since we are taking two query one for master and other for details and then we are joining them on common data item.If it is same then we can directly use the join operator present in report studio.Please share your experience.
Thanks in advance 

[Lynn]

A master-detail is going to fire a detail query for each and every row in the master query based on the master detail condition you specify. I think there were some performance enhancements done somewhere along the line so that it isn't quite that taxing, but conceptually I do believe what is happening. The detail query is filtered by the master.

A join is going to fire query1 to get a result set, then fire query2 to get a result set, and lastly combine the two result sets locally on the Cognos server based on the join condition so you get one big result set with the combined data from both queries.

For me it comes down to performance and the layout I am trying to achieve.

[sunny bachan prasad]

Thanks Lynn to share your experience :)