On 9th of April, Tom Lane committed patch: Support indexing of regular-expression searches in contrib/pg_trgm. This works by extracting trigrams from the given regular expression, in generally the same spirit as the previously-existing support for LIKE searches, though of course the details are far ...

On 1st of February, Tom Lane committed patch: Support LIKE and ILIKE index searches via contrib/pg_trgm indexes.   Unlike Btree-based LIKE optimization, this works for non-left-anchored search patterns. The effectiveness of the search depends on how many trigrams can be extracted from the pattern. ...