Sometimes when we are working with our mapping, it is necessary to store some additional data to be used for display purpose, ORM facilities, permissions, or simply to track them in the mapping.
ElasticSearch allows storing every kind of JSON data we want in the mapping, with the special _meta field.
The _meta mapping field can be populated with every data we want. For example:
{
"order": {
"_meta": {
"attr1": ["value1", "value2"],
"attr2": {
"attr3": "value3"
}
}
}
}When ElasticSearch processes a mapping and finds a _meta field, it stores it in the global mapping status aligned in all the cluster nodes.
The _meta field is only for storing purposes; it's not indexed and searchable.
