A LIKE predicate in which a column is compared to a character string that begins with a character constant (not a wildcard) is transformed into three predicates: one predicate that uses the LIKE operator, one that uses the >= operator, and one that uses the < operator.
For example,
country LIKE 'Ch%i%'
becomes
country LIKE 'Ch%i%' AND country >= 'Ch' AND country < 'Ci'
The first (LIKE) predicate is not optimizable, but the new predicates added by the transformation are.
When the character string begins with one more character constants and ends with a single "%", the first LIKE clause is eliminated. For example,
country LIKE 'Ch%'
becomes
country >= 'Ch' AND country < 'Ci'