Both Couchbase Server and Elasticsearch enable you to flexibly model data by using JSON documents to represent your application objects. These documents generally contain all the information about a data entity, and can be as complex as you choose. You can use nested data and structures such as arrays and hashes to provide additional information about your object. You also do not need to perform schema migrations for JSON documents. Instead you can flexibly write new data fields or values to represent new information in your documents.

Be aware that Elasticsearch automatically creates a mapping which defines what is searchable in your documents. So how you design your documents for search is influenced by Elasticsearch mappings. This guide is not intended to be an exhaustive description on how to model documents for use in Elasticsearch or how to modifying mapping in Elasticsearch.

There are a few document design considerations you should have in mind if you are going to use Couchbase Server with Elasticsearch. For instance, imagine you have a document to represent a product as follows:

Imagine your inventory system changes and you want to change your product SKU so that it is an integer. With the flexibility of JSON, you can update the schema for your product to look like this in Couchbase Server:

By design, there may be some cases where you do not want to update all your products to have integer SKUs. This may be an intentional design choice if your application logic does not depend on it, or you may want to change your application logic to handle both string and integer SKUs.

When you use Elasticsearch, it will generate a default mapping used to index items; this mapping describes how particular fields should be indexed. By default, Elasticsearch builds a mapping based on documents transmitted to it and it will make assumptions and generalizations about all documents based on the initial documents it receives. Each default mapping will assume specific data types for each field. Be aware that even though you can change a field type for a document in Couchbase Server, it can cause problems for Elasticsearch if you do not also update the default mapping. If you change the field type in Couchbase Server, Elasticsearch will not index the new documents containing the different field type and you will not receive the document ID as a search query. In this case, because we change the SKU from a string to an integer, all the products we add to our system with the integer SKU will not be indexed by Elasticsearch using the default mapping.

To resolve this, whenever you update a document schema you probably want to update all documents which contain that field. In our example, we update the SKU field so that all documents have integers for SKUs. Elasticsearch will receive all updates to existing products and then index them. For more general information about data modeling for Couchbase Server, see the Modeling Data section in the Couchbase Developer Guide,.

{
    "object1" : [
        {
            "name" : "blue",
            "count" : 4
        },
        {
            "name" : "green",
      "count" : 6
     }
    ]
}