From what I've been reading, index_analyzer should analyze during indexing, and search_analyzer when querying. But I still can't wrap my head around this completely, it sounds pretty simple and straightforward, but when and where would we use this? Does anyone have an example to make this a bit clearer?
Synonyms.
You either decide to expand "doggy" to also use "dog" at index time for docs or search time for queries. No need to do both.