The following command would upgrade the older version of pg_bigm to 1.2.
ALTER EXTENSION pg_bigm UPDATE TO '1.2';
Make pg_bigm available for parallel queries that was introduced in PostgreSQL 9.6 (Fujii Masao)
Support triConsistent method that was introduced in PostgreSQL 9.4, for better performance (Fujii Masao)
In 9.4 or later, the triConsistent method makes the full-text search using pg_bigm much faster especially when a long search phrase is used.
Improve performance of similarity search (Fujii Masao)