I was optimizing some queries today and I discovered that WHERE LIKE %% is much faster than WHERE = on a text based row. Here is an example of what I mean:
0.002 second execution time:
WHERE tbl LIKE '%joe%'
6.8 second execution time:
WHERE tbl='joe'
I have no idea why and it didn't make much sense if MySQL had to search for a value vs. finding an exact. It would seem an exact value would be faster than a searched like value.
