How it works...

During indexing, when Elasticsearch processes a fields property of type multifield, it reprocesses the same field for every subfield defined in the mapping.

To access the subfields of a multifield, we have a new path built on the base field plus the subfield name. If we consider the preceding example, we have the following:

• name: This points to the default multifield subfield-field (the keyword one)
• name.tk: This points to the standard analyzed (tokenizated) text field
• name.code: This points to a field analyzed with a code extractor analyzer

As you may have noticed in the preceding example, we have changed the analyzer to introduce a code extractor analyzer that allows you to extract the item code from a string.

Using the multifield, if we index a string such as Good Item to buy - ABC1234, we'll have the following:

• name = Good Item to buy - ABC1234 (useful for sorting)
• name.tk= ["good", "item", "to", "buy", "abc1234"] (useful for searching)
  • name.code = ["ABC1234"] (useful for searching and faceting)