Question

I have an SQL query similar to below:

SELECT NAME,
       MY_FUNCTION(NAME) -- carries out some string manipulation
  FROM TITLES
  ORDER BY NAME; -- has an index.

The TITLES table has approximately 12,000 records. At the moment the query takes over 5 minutes to execute but if I remove the ORDER BY clause then it executes within a couple of seconds.

Does anyone have any suggestions on how to be speed up this query.

Answer 1

Use the EXPLAIN statement to see where the issue is

EXPLAIN SELECT NAME, MY_FUNCTION(NAME) FROM TITLES ORDER BY NAME;