* Introduce ParentJoinFieldMapper, a field mapper that creates parent/child relation within documents of the same index
This change adds a new field mapper named ParentJoinFieldMapper. This mapper is a replacement for the ParentFieldMapper but instead of using the types in the mapping
it uses an internal field to materialize parent/child relation within a single index.
This change also adds a fetch sub phase that automatically retrieves the join name (parent or child name) and the parent id for child documents in the response hit fields.
The compatibility with `has_parent`, `has_child` queries and `children` agg will be added in a follow up.
Relates #20257
Removes the need for the `_UNRELEASED` suffix on versions by detecting if a version should be unreleased or not based on the versions around it. This should make it simpler to automate the task of adding a new version label.
This commit moves the handling of nested and parent/child inner hits to specialized classes that can be defined outside of ES core.
InnerHitBuilderContext is now used by the parent query (nested or hasChild, ...) to build the sub context from the InnerHitBuilder definition.
BWC is also ensured so that nodes in previous versions can still send/receive inner hits to/from this version.
Relates #20257
This change removes the field data specialization needed for the parent field and replaces it with
a simple DocValuesIndexFieldData. The underlying global ordinals are retrieved via a new function called
IndexOrdinalsFieldData#getOrdinalMap.
The children aggregation is also modified to use a simple WithOrdinals value source rather than the deleted WithOrdinals.Parent.
Relates #20257
This commit renames all rest test files to use the .yml extension
instead of .yaml. This way the extension used within all of
elasticsearch for yaml is consistent.
* Add parent-join module
This change adds a new module named `parent-join`.
The goal of this module is to provide a replacement for the `_parent` field but as a first step this change only moves the `has_child`, `has_parent` queries and the `children` aggregation to this module.
These queries and aggregations are no longer in core but they are deployed by default as a module.
Relates #20257
Jim Ferenczi
Nik Everett
javanna
Ryan Ernst
Christoph Büscher