How to define dynamically / override the _default_ mapping in elasticsearch? - elasticsearch

Question

Use case :
The index/indices will be built dynamically from a template, so that
it will pick some custom settings (number of shards/replicas/ etc).
Generate dynamically the types and their mappings, enabling for them all the timestamp
& ttl fields. Also define the same parent type for all types, except
the parent type itself (I know its name).
{
"template": "*",
"settings": {
...................
},
"mappings": {
"_default_": {
"_parent": {
"type": "ParentType"
},
"_timestamp": {
"enabled": true,
"store": true
},
"_ttl": {
"enabled": true
}
}
}
}
How could I disable the _parent field for the ParentType type itself ?

Answer 1

After a little big of digging on the docs, I found out that you can override __default__ mappings using this work around.
{
"mappings": {
"_default_": {
"_parent": {
"type": "my_parent_type" # 1
}
},
"my_parent_type": {
"_parent": {
"type": "_dummy" # 2
}
}
}
}
1) This mapping configuration will be inherited by all your types including my_parent_typetype. Step 2 explains how to override your parent type _parent meta-field.
2) I found here https://www.elastic.co/guide/en/elasticsearch/reference/current/default-mapping.html that you can override any of the mappings from __default__ when you provide a specific mapping for the type in question.
In this case we are assigning the _parent mapping of my_parent_type to a _dummy parent type that does not have to exists in your index.
Note: ElasticSearch 2.x documentation states:
The _parent.type setting can only point to a type that doesn’t exist yet. This means that a type cannot become a parent type after it is has been created.
For this reason, you have to make sure you index first, a document that is not my_parent_type type, otherwise you'll get an at indexing time.
I hope this helps.