Do I need 'index' on all columns in WHERE clause

akrashdi · #1 (**permalink**) 07-20-11, 19:01

I have index on key_logId, do I need to have an index on log_actionPerformed too?

Code:

SELECT log_dateTime, log_actionPerformed FROM log_trips WHERE key_logId = 5 AND log_actionPerformed LIKE 'note%' ORDER BY key_logId;

r937 · #2 (**permalink**) 07-20-11, 19:21

not necesarily, but it couldn't hurt to try

mysql will use only one index for each SELECT

do an EXPLAIN on your query, add the second index, then do another EXPLAIN

see if there's any difference

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