Optimizing join query performance in google app engine
The standard solution to this problem is denormalization.  Try storing a copy of price and profit in Entity1 and then you can answer your question with a single, simple query on Entity1.
Scenario

Entity1 (id,itmname)
Entity2 (id,itmname,price)
Entity3 (id,itmname,profit)
profit and price are both IntegerProperty

I want to count all the item with price more then 500 and profit more then 10.
I know its join operation and is not supported by google. I tried my best to find out the way other then executing queries separately and performing count but I didn't get anything. 
The reason for not executing queries separately is query execution time. In each query I am getting more then 50000 records as result so it takes nearly 20 seconds in fetching records from first query.