Indexing fields


I have a question about indexing fields. At the moment, some of my fields are indexed while others are not. There are fields like "foo" (just an example) that are not indexed but "foo.raw" is.

I don't understand what determines if a field will be indexed and when a field won't be. Is there a way to index fields without having to completely remove the entire Elasticsearch index? If the "foo.raw" field is indexed, how can you force the "foo" field to be indexed as well.

Sorry if these questions seem silly.

Have you read the mapping documentation?