MariaDB is using case and accent insensitive collation for full text search by default, you can specify a different collation here, for example:
$CFG->dboptions['ftslanguage'] = 'utf8_unicode_ci';
$CFG->dboptions['ftslanguage'] = 'utf8mb4_0900_as_ci';
$CFG->dboptions['ftslanguage'] = 'utf8mb4_de_pb_0900_ai_ci';
MariaDB does not support Japanese and other languages with very short words without spaces in between, enable the following setting to get a basic experimental support of these languages:
$CFG->dboptions['fts3bworkaround'] = true;
After any of these changes re-populate FTS tables by running:
Minimum search term length
MariaDB default search char limit can be changed by editing configuration file:
Stop words is a dictionary of words that will be excluded from index and search query. They depend on language being used during indexing and search as well as dictionary presence for database installation e.g. if user search for "Hotels in Wellington" then the system excludes "In" words from the search.
More details on MariaDB stop words can be found at: https://mariadb.com/kb/en/library/full-text-index-stopwords/
Unfortunately, MariaDB does not support NGRAM plugin that is used in MySQL to perform word stemming, so we cannot advise at this stage how to enable morphological search in MariaDB yet.
By default, MariaDB does support diacritics but it depends on collation. For example, when collation is utf8_general_ci, then the search query containing either word 'första' or 'forsta' will return a record containing word 'första'.