Why "snowball" analyser was removed in Elasticsearch 5.1

Question

I had Elasticsearch 2.4 and many of my indexes where using "snowball" analyzer, however today I updated to 5.1 and this analyzers stop working, Why did they where removed and how to convert my "snowball" analyzers to the equivalent in 5.1?

Answer 1

The main reason was because the snowball analyzer has been removed in Lucene 5 and replaced by the english analyzer (more info here)

The snowball token filter is still there, though, so nothing prevents you from building a custom analyzer mimicking the snowball analyzer:

{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_snowball": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": ["standard", "lowercase", "stop", "snowball"]
        }
      }
    }
  }
}