This doesn't seem either buggy or strange... An index on the ordering of that column is not helpful in handling a leading wildcard, and so the query optimizer will, in such cases, revert, correctly, to using a sequential scan and filtering the results.
If you have cases where this sort of wildcard needs to be fast, a functional index could help. Create index foo on tbl (reverse(col)); And reverse the wildcard so the index is usable: Select * from tbl where reverse(col) like 'esrever%'; That query can harness the reversed index. Unfortunately, no ordered index helps with Select * from too where col like '%something%'; For that, a full text search index can help, but that is a longer story. At any rate, what you are observing is no surprise, and consistent with what many database systems do.
