Is substr or LIKE faster in Oracle?

Question

Would

WHERE substr(my_field,1,6) = \'search\'

or

WHERE my_field LIKE \'search%\'

be faster in Oracle, o

Answer 1

I would profile both. But I would guess the 'LIKE' would be much faster, because it uses the binary search on the index (if the field is indexed). If you use the SUBSTR method, you will end up with a full table scan, as Oracle has to process row by row the function.