SQL query plan

Belias

Hi everyone, can someone tell me how to decypher this query plan, or better where can i find a guide which explains all the operators? (i found on msdn something which explains the words, but what about the numbers like [2,1],[3,2] etc? thanks in advance

Sort[2,1];Filter[3,2];Nested Loops[4,3];Index Seek($3)[5,4];Clustered Index Seek(Company$Cylinder Rental Calculation$0)[7,4]

stryk

Sort[2,1];Filter[3,2];Nested Loops[4,3];Index Seek($3)[5,4];Clustered Index Seek(Company$Cylinder Rental Calculation$0)[7,4]

Actually you have to read the QEP from right to left:

1. SQL Server perfroms a "Seek" on non-clustered Index "$3" (this is usually the best index matching to the WHERE clause)
2. As NAV always executes a SELECT * (= all fields) the SQL Server has to perfrom a "Key Lookup", e.g. a "Seek" on the Clustered Index "Company$Cylinder Rental Calculation$0" to retrieve all other fields from the table
3. The results are combined and filtered
4. The result is sorted to match the ORDER BY clause

That should be it ... more or less ...

Belias

Thanks! and what about the numbers within square brackets? e.g.: [3,2]
Is there a documentation for all this?(i found something on msdn, but the square brackets numbers are not explained)

stryk

Sorry, I don't know what the [x,y] mean ... :-k

Here some info about QEP: http://www.sql-server-performance.com/tips/query_execution_plan_analysis_p1.aspx

Belias

thanks, anyway