Synonyms in Solr (query time vs time index)
There's a very good review there at http://nolanlawson.com/2012/10/31/better-synonym-handling-in-solr/ ... I remembered this because I recently had the same question and found that via google * wink wink *.
Basically, there is a huge difference between both, and you may need to use both at the end, depending on what you are trying to achieve.
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