Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Is there any tangible difference (speed/efficiency) between these statements? Assume the column is indexed.
SELECT MAX(someIntColumn) AS someIntColumn
or
SELECT someIntColumn ORDER BY someIntColumn DESC LIMIT 1
This depends largely on the query optimizer in your SQL implementation. At best, they will have the same performance. Typically, however, the first query is potentially much faster.
The first query essentially asks for the DBMS to inspect every value in
someIntColumnand pick the largest one.The second query asks the DBMS to sort all the values in
someIntColumnfrom largest to smallest and pick the first one. Depending on the number of rows in the table and the existence (or lack thereof) of an index on the column, this could be significantly slower.If the query optimizer is sophisticated enough to realize that the second query is equivalent to the first one, you are in luck. But if you retarget your app to another DBMS, you might get unexpectedly poor performance.