* Make fields optional in multi_match query and rely on index.query.default_field by default
This commit adds the ability to send `multi_match` query without providing any `fields`.
When no fields are provided the `multi_match` query will use the fields defined in the index setting `index.query.default_field`
(which in turns defaults to `*`).
The same behavior is already implemented in `query_string` and `simple_query_string` so this change just applies
the heuristic to `multi_match` queries.
Relying on `index.query.default_field` rather than `*` is safer for big mappings that break the 1024 field expansion limit added in 7.0 for all
text queries. For these kind of mappings the admin can change the `index.query.default_field` in order to make sure that exploratory queries using
`multi_match`, `query_string` or `simple_query_string` do not throw an exception.
Add fuzzy_transpositions parameter to multi_match and query_string queries.
Add fuzzy_transpositions, fuzzy_prefix_length and fuzzy_max_expansions
parameters to simple_query_string query.
* Add support for auto_generate_synonyms_phrase_query in match_query, multi_match_query, query_string and simple_query_string
This change adds a new parameter called auto_generate_synonyms_phrase_query (defaults to true).
This option can be used in conjunction with synonym_graph token filter to generate phrase queries
when multi terms synonyms are encountered.
For example, a synonym like "ny, new york" would produce the following boolean query when "ny city" is parsed:
((ny OR "new york") AND city)
Note how the multi terms synonym "new york" produces a phrase query.
Currently `fuzziness` is not supported for the `cross_fields` type
of the `multi_match` query since it complicates the logic that
blends the term queries that cross_fields uses internally. At the
moment using this combination is silently ignored, which can lead to
confusions. Instead we should throw an exception in this case.
The same is true for phrase and phrase_prefix type.
Closes#7764
The `multi_match` query groups terms that have the same analyzer together and
then applies the boost of the first query in each group. This is not necessary
given that boosts for each term are already applied another way.
This commit makes queries and filters parsed the same way using the
QueryParser abstraction. This allowed to remove duplicate code that we had
for similar queries/filters such as `range`, `prefix` or `term`.