What is the impact of "varchar_pattern_ops" on performance and/or memory (was: What is impact of "varchar_ops")?

I'm rephrasing the question I posted yesterday, because I have used the
wrong terminology and caused confusion (and for instance, got no
response to my question).

Almost all indexed columns of kind varchar in my database require
"varchar_pattern_ops" op class in order to make my LIKE queries more
optmized.

Is there any way to define that this operator class is the default for
my database for varchar columns?

What would be the impact in terms of performance and memory consumption?


Thanks,

Edson Richter