Adding a new analyzer into existing index in Elasticsearch (requires close/open the index). Tested with Elasticsearch 0.19.12.

gistfile1.js

// create an index with an analyzer "myindex"
curl -X PUT localhost:9200/myindex -d '
{
  "settings" : {`
    "index":{
      "number_of_replicas":0,
      "number_of_shards":1,
      "analysis":{
        "analyzer":{
          "first":{
            "type":"whitespace"
          }
        }
      }
    }
  }
}'

// verify analyzers for "myindex"
curl -XGET 'http://localhost:9200/_cluster/state?pretty&filter_nodes=true&filter_routing_table=true&filter_indices=myindex'

# {
#   "cluster_name" : "elasticsearch",
#   "blocks" : { },
#   "metadata" : {
#     "templates" : { },
#     "indices" : {
#       "myindex" : {
#         "state" : "open",
#         "settings" : {
#           "index.number_of_replicas" : "0",
#           "index.number_of_shards" : "1",
#           "index.analysis.analyzer.first.type" : "whitespace",
#           "index.version.created" : "191299"
#         },
#         "mappings" : { },
#         "aliases" : [ ]
#       }
#     }
#   }
# }

// try to add a new analyzer
curl -XPUT 'localhost:9200/myindex/_settings' -d '{
  "analysis" : {
    "analyzer":{
      "second":{
        "type":"custom",
        "tokenizer":"whitespace",
        "filter":["lowercase"]
      }
    }
  }
}'

# {"ok":true}

// but in fact index setting is not modified - the following is found in the log
[WARN ][cluster.metadata         ] [Captain Omen] [myindex] ignoring non dynamic index level settings for open indices: [index.analysis.analyzer.second.type, index.analysis.analyzer.second.tokenizer, index.analysis.analyzer.second.filter.0]

// close the index
curl -XPOST 'localhost:9200/myindex/_close'

# {"ok":true,"acknowledged":true}

// we can verify index is closed
curl -XGET 'http://localhost:9200/_cluster/state?pretty&filter_nodes=true&filter_routing_table=true&filter_indices=myindex'

# {
#   "cluster_name" : "elasticsearch",
#   "blocks" : {
#     "indices" : {
#       "myindex" : {
#         "4" : {
#           "description" : "index closed",  // <--- myindex is closed
#           "retryable" : false,
#           "levels" : [ "read", "write" ]
#         }
#       }
#     }
#   },
#   "metadata" : {
#     "templates" : { },
#     "indices" : {
#       "myindex" : {
#         "state" : "close",  // <--- state: close
#         "settings" : {
#           "index.number_of_replicas" : "0",
#           "index.number_of_shards" : "1",
#           "index.analysis.analyzer.first.type" : "whitespace",
#           "index.version.created" : "191299"
#         },
#         "mappings" : { },
#         "aliases" : [ ]
#       }
#     }
#   }
# }

// try to add a new analyzer again
curl -XPUT 'localhost:9200/myindex/_settings' -d '{
  "analysis" : {
    "analyzer":{
      "second":{
        "type":"custom",
        "tokenizer":"whitespace",
        "filter":["lowercase"]
      }
    }
  }
}'

# {"ok":true}

// we can add a new analyzer now
curl -XGET 'http://localhost:9200/_cluster/state?pretty&filter_nodes=true&filter_routing_table=true&filter_indices=myindex'

# {
#   "cluster_name" : "elasticsearch",
#   "blocks" : {
#     "indices" : {
#       "myindex" : {
#         "4" : {
#           "description" : "index closed",
#           "retryable" : false,
#           "levels" : [ "read", "write" ]
#         }
#       }
#     }
#   },
#   "metadata" : {
#     "templates" : { },
#     "indices" : {
#       "myindex" : {
#         "state" : "close",
#         "settings" : {
#           "index.number_of_replicas" : "0",
#           "index.number_of_shards" : "1",
#           "index.analysis.analyzer.first.type" : "whitespace",
#           "index.version.created" : "191299",
#           "index.analysis.analyzer.second.tokenizer" : "whitespace",
#           "index.analysis.analyzer.second.type" : "custom",
#           "index.analysis.analyzer.second.filter.0" : "lowercase"
#         },
#         "mappings" : { },
#         "aliases" : [ ]
#       }
#     }
#   }
# }

// open the index now
curl -XPOST 'localhost:9200/myindex/_open'

# {"ok":true,"acknowledged":true}

// now everything seems to be ok
curl -XGET 'http://localhost:9200/_cluster/state?pretty&filter_nodes=true&filter_routing_table=true&filter_indices=myindex'

# {
#   "cluster_name" : "elasticsearch",
#   "blocks" : { },
#   "metadata" : {
#     "templates" : { },
#     "indices" : {
#       "myindex" : {
#         "state" : "open",
#         "settings" : {
#           "index.number_of_replicas" : "0",
#           "index.number_of_shards" : "1",
#           "index.analysis.analyzer.first.type" : "whitespace",
#           "index.version.created" : "191299",
#           "index.analysis.analyzer.second.tokenizer" : "whitespace",
#           "index.analysis.analyzer.second.type" : "custom",
#           "index.analysis.analyzer.second.filter.0" : "lowercase"
#         },
#         "mappings" : { },
#         "aliases" : [ ]
#       }
#     }
#   }
# }

He nitingadekar
Opening and closing indices on AWS elasticsearch is not supported.
https://docs.aws.amazon.com/en_pv/elasticsearch-service/latest/developerguide/aes-supported-es-operations.html

As an update on opening and closing indicies on AWS ES/OpenSearch, this is supported as of V7.4

https://docs.aws.amazon.com/opensearch-service/latest/developerguide/supported-operations.html#version_7_4

But we still need to reindex. such settings doesnt apply to existing data :(