elasticsearch routing on specific field - elasticsearch

Question

hi I want to set custom routing on specific field "userId" on my Es v2.0.
But it giving me error.I don't know how to set custom routing on ES v2.0
Please guys help me out.Thanks in advance.Below is error message, while creating custom routing with existing index.
{
"error": {
"root_cause": [
{
"type": "mapper_parsing_exception",
"reason": "Mapping definition for [_routing] has unsupported parameters: [path : userId]"
}
],
"type": "mapper_parsing_exception",
"reason": "Mapping definition for [_routing] has unsupported parameters: [path : userId]"
},
"status": 400
}

Answer 1

In ES 2.0, the _routing.path meta-field has been removed. So now you need to do it like this instead:
In your mapping, you can only specify that routing is required (but you cannot specify path anymore):
PUT my_index
{
"mappings": {
"my_type": {
"_routing": {
"required": true
},
"properties": {
"name": {
"type": "string"
}
}
}
}
}
And then when you index a document, you can specify the routing value in the query string like this:
PUT my_index/my_type/1?routing=bar
{
"name": "foo"
}

Answer 2

You can still use custom routing based on a field from the data being indexed. You can setup a simple pipeline and then use the pipeline every time you index a document, or you can also change the index settings to use the pipeline whenever the index receives a document indexing request.
Read about the pipeline here
Do read above and below the docs for more clarity. It's not meant for setting custom routing, but can be used for the purpose. Custom routing was disabled for a good reason that the field to be used can turn out to have null values leading to unexpected behavior. Hence take care of that issue by yourself.
For routing, here is a sample pipeline PUT :
PUT localhost:9200/_ingest/pipeline/nameRouting
Content-Type: application/json
{
"description" : "Set's the routing value from name field in document",
"processors" : [
{
"set" : {
"field": "_routing",
"value": "{{_source.name}}"
}
}
]
}
The index settings will be :
{
"settings" : {
"index" : {
"default_pipeline" : "nameRouting"
}
}
}