This commit introduces a new execution mode for the query_string query, which
is intended down the road to be a replacement for the current _all field.
It now does auto-field-expansion and auto-leniency when the following criteria
are ALL met:
The _all field is disabled
No default_field has been set in the index settings
No default_field has been set in the request
No fields are specified in the request
Additionally, a user can force the "all-like" execution by setting the
all_fields parameter to true.
When executing in all field mode, the query_string query will look at all the
fields in the mapping that are not metafields and can be searched, and
automatically expand the list of fields that are going to be queried.
Relates to #19784
Lucene 6.2 introduces the new `Analyzer.normalize` API, which allows to apply
only character-level normalization such as lowercasing or accent folding, which
is exactly what is needed to process queries that operate on partial terms such
as `prefix`, `wildcard` or `fuzzy` queries. As a consequence, the
`lowercase_expanded_terms` option is not necessary anymore. Furthermore, the
`locale` option was only needed in order to know how to perform the lowercasing,
so this one can be removed as well.
Closes#9978
This change adds an option called `split_on_whitespace` which prevents the query parser to split free text part on whitespace prior to analysis. Instead the queryparser would parse around only real 'operators'. Default to true.
For instance the query `"foo bar"` would let the analyzer of the targeted field decide how the tokens should be splitted.
Some options are missing in this change but I'd like to add them in a follow up PR in order to be able to simplify the backport in 5.x. The missing options (changes) are:
* A `type` option which similarly to the `multi_match` query defines how the free text should be parsed when multi fields are defined.
* Simple range query with additional tokens like ">100 50" are broken when `split_on_whitespace` is set to false. It should be possible to preserve this syntax and make the parser aware of this special syntax even when `split_on_whitespace` is set to false.
* Since all this options would make the `query_string_query` very similar to a match (multi_match) query we should be able to share the code that produce the final Lucene query.
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`.
Lee Hinman
Adrien Grand
Jim Ferenczi
Isabel Drost-Fromm
Isabel Drost-Fromm
Christoph Büscher
Clinton Gormley