re: Improving SQL Query by Adding conditions in Joins VIEW POST

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re: You were just lucky. Query optimizer has chosen a non cached version of plan to execute this query.
 

I don't think that was the case, Execution plans for both queries are different, Also these queries were executing frequently and I saw the difference even executing them in parallel (half queries in old way and half in new way simultaneously).

 

Plans have obviously have to be different.

I see this is SQL Server and it will cache plan for an exact query you run. By moving date time clause to join condition you force a new plan generation.

You should be able to get same results by forcing plan recompilation

I looked at my query again and I found out that I had an extra clause NOT EXISTS which was causing difference in speed and plans, omitting not EXISTS didn't make difference in speed in both cases.

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