> The SQL is very simple:
> 'select * from palavra where original like '%a' and ordenada not
> like 'a%' and original=ordenada'

The SQL is syntactically simple. But, tu get the result the DB has to
read all records in Table - no index can be used.

You should not tals about performance on such queries. You should
consider what kind of queries is required for your application. If you
cannot find an performant solution you should post an problem
description - perhaps someone on the list can help you.

Elmar