Indexes in OpenSearch

When saving a document to OpenSearch, it is indexed and placed in a user-specified index, making it available for search and analysis. One may think of an index as a data table in a traditional DBMS.

In OpenSearch, a document is a set of fields where each field is a key: value pair. The index stores optimized documents to enable quickly searching documents by field. Such optimization is achieved with each document field having a specific type. This is how the field data is effectively stored in the index. For more information about this type of optimization, see the OpenSearch documentation.

Unlike a traditional DBMS, to save the document in the index, OpenSearch does not require the explicit specification of the schema, i.e., links between document fields and their types. Even though it is the recommended approach, you can save documents to the index without explicitly specifying the field types; OpenSearch will try to determine the type automatically for each field in the document. As a result, you can quickly add documents to OpenSearch storage and start working with them.

To learn more about how indexes work, see the OpenSearch documentation.

In multihost clusters, index sharding and replication are supported. This makes it easier to scale the cluster and improves fault tolerance.