Insert statement takes too long to finish

Question

I am trying to Insert some data from one table to another in SQL Server , but it takes too long to finish even when affected rows are 0.

Below is the query I am using to Insert :

INSERT INTO Table_1 (Prop_1, Prop_2)
    SELECT @passedParam , Prop_2 
    FROM Table_2
    WHERE Prop_1 = @passedParam - 1 
      AND Prop_2 NOT IN (SELECT Prop_2 
                         FROM Table_2
                         WHERE Prop_1 = @passedParam)

Some additional information:

• This query is inside a stored procedure which takes @passedParam as a parameter
• Table_2 contains around 28,000 rows
• I am filtering Table_2 and inserting result into Table_1 based on some logic. Prop_1 and Prop_2 are regular columns, not PK or FK and datatypes are INT and BIGINT
• I have commented out every other statement in the stored procedure, only this one takes so much time (Up to 50 sec to finish even when affected rows are equal to 0)

Can anyone explain what the issue is, and why it takes so long to finish?

Please tell if there is a faster way to insert data into the table.

Answer 1

Try this way :

INSERT INTO Table_1 
       (Prop_1,      Prop_2)
SELECT @passedParam, Prop_2 
FROM   Table_2
WHERE  Prop_1 = @passedParam - 1 
EXCEPT
SELECT Prop_2, @passedParam 
FROM   Table_2
WHERE  Prop_1 = @passedParam;