Currently the SynonymsFilterFactory builds up a memory based SynonymsMap.
This can generate huge maps because of the permutations for synonyms.
Now where FST (finite state transducer) is introduced to lucene this could also be used for synonyms.
A tool can compile the synoynms.txt file to a binary automaton file which can then be used
- faster start of solr, no need to generate SynonymsMap
- faster lookup
- memory saving