Document representing a query. A query contains a set of objects that define criteria
used to select records. A query can contain one of the following:
- match_all_query - returns all records.
- term_query - matches records where a field (or fields) exactly match some simple value (including null).
- text_query - matches records where a field (or fields) contain a search phrase.
- boolean_query - formulates a complex boolean expression using query objects as criteria.
- filtered_query - allows for filtering of records based on both a query and a filter.