Question

Query –

Select * FROM tbl1 
LEFT OUTER JOIN tbl2 ON  tbl1.id   = tbl2.id 
                     AND tbl2.col2 = 'zyx' 
                     AND tbl2.col3  = 'abc' 
WHERE tbl1.col1 = 'pqr'

Here I’m doing left outer join and using ‘and’ along with join.
(First I was using joins ‘and’ part in ‘where’ but my results were not correct)

My query, which is very similar to this, runs for a long time; it takes at least 10 seconds to run. Is there a way to optimize these types of query?

Answer 1

Create the following indexes:

CREATE INDEX ix_tbl1_1_id ON tbl1 (col1, id)
CREATE INDEX ix_tbl2_2_3_id ON tbl2 (col2, col3, id)

If id is a CLUSTERED PRIMARY KEY in the corresponding tables, you can omit it from the index, since it will be implicitly included there anyway:

CREATE INDEX ix_tbl1_1 ON tbl1 (col1)
CREATE INDEX ix_tbl2_2_3 ON tbl2 (col2, col3)