No, it just depends on the query optimizer. Some databases have query optimizers that know how to use an index when told "LIKE 'blah%'". Some database have query optimizers that know how to use an index when told the equivalent thing using SUBSTR(). Some databases have optimizers that know how to do both. Some neither.

- tye        

In reply to Re^4: same query, different execution, different performance (substr) by tye
in thread same query, different execution, different performance by punkish

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