"Rodrigo Hjort" <rodrigo.hjort@gmail.com> writes:
> What happens is that only the "004" block uses the index! The "002" code,
> which also has no leading percent, does a sequential scan. The difference
> between them is that "002" uses bind parameters.

Yeah. The LIKE index optimization depends on seeing a constant LIKE
pattern at plan time --- otherwise the planner doesn't know what
indexscan parameters to generate. So a bound-parameter query loses.

Ideas for improving this situation are welcome ... it's not an easy
problem ...

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match