The shard suggestion sort uses a different tie-break than the one that is used
to merge different shards responses. The former uses the internal document identifier
when scores are the same whereas the latter compares the surface form first.
Because of this discrepancy some suggestion outputs are linked to the wrong documents
because the merge sort reorders the shard suggestions differently. This change
fixes this bug by duplicating the Lucene collector in order to be able to apply the
same tiebreak strategy than the merge sort. This logic will be removed when
https://issues.apache.org/jira/browse/LUCENE-8529 is fixed.

Closes #34378

Relates #34508

Relates #34508

This commit adds a new ParentJoinAggregator that implements a join using global ordinals
in a way that can be reused by the `children` and the upcoming `parent` aggregation.
This new aggregator is a refactor of the existing ParentToChildrenAggregator with two main changes:
* It uses a dense bit array instead of a long array when the aggregation does not have any parent.
* It uses a single aggregator per bucket if it is nested under another aggregation.
For the latter case we use a `MultiBucketAggregatorWrapper` in the factory in order to ensure that each
instance of the aggregator handles a single bucket. This is more inlined with the strategy we use for other
aggregations like `terms` aggregation for instance since the number of buckets to handle should be low (thanks to the breadth_first strategy).
This change is also required for elastic#34210 which adds the `parent` aggregation in the parent-join module.

Relates elastic#34508

)

This commit adds a new ParentJoinAggregator that implements a join using global ordinals
in a way that can be reused by the `children` and the upcoming `parent` aggregation.
This new aggregator is a refactor of the existing ParentToChildrenAggregator with two main changes:
* It uses a dense bit array instead of a long array when the aggregation does not have any parent.
* It uses a single aggregator per bucket if it is nested under another aggregation.
For the latter case we use a `MultiBucketAggregatorWrapper` in the factory in order to ensure that each
instance of the aggregator handles a single bucket. This is more inlined with the strategy we use for other
aggregations like `terms` aggregation for instance since the number of buckets to handle should be low (thanks to the breadth_first strategy).
This change is also required for #34210 which adds the `parent` aggregation in the parent-join module.

Relates #34508

)

This commit adds a new ParentJoinAggregator that implements a join using global ordinals
in a way that can be reused by the `children` and the upcoming `parent` aggregation.
This new aggregator is a refactor of the existing ParentToChildrenAggregator with two main changes:
* It uses a dense bit array instead of a long array when the aggregation does not have any parent.
* It uses a single aggregator per bucket if it is nested under another aggregation.
For the latter case we use a `MultiBucketAggregatorWrapper` in the factory in order to ensure that each
instance of the aggregator handles a single bucket. This is more inlined with the strategy we use for other
aggregations like `terms` aggregation for instance since the number of buckets to handle should be low (thanks to the breadth_first strategy).
This change is also required for #34210 which adds the `parent` aggregation in the parent-join module.

Relates #34508

The shard suggestion sort uses a different tie-break than the one that is used
to merge different shards responses. The former uses the internal document identifier
when scores are the same whereas the latter compares the surface form first.
Because of this discrepancy some suggestion outputs are linked to the wrong documents
because the merge sort reorders the shard suggestions differently. This change
fixes this bug by duplicating the Lucene collector in order to be able to apply the
same tiebreak strategy than the merge sort. This logic will be removed when
https://issues.apache.org/jira/browse/LUCENE-8529 is fixed.

Closes #34378

Relates #34508

)

This commit adds a new ParentJoinAggregator that implements a join using global ordinals
in a way that can be reused by the `children` and the upcoming `parent` aggregation.
This new aggregator is a refactor of the existing ParentToChildrenAggregator with two main changes:
* It uses a dense bit array instead of a long array when the aggregation does not have any parent.
* It uses a single aggregator per bucket if it is nested under another aggregation.
For the latter case we use a `MultiBucketAggregatorWrapper` in the factory in order to ensure that each
instance of the aggregator handles a single bucket. This is more inlined with the strategy we use for other
aggregations like `terms` aggregation for instance since the number of buckets to handle should be low (thanks to the breadth_first strategy).
This change is also required for #34210 which adds the `parent` aggregation in the parent-join module.

Relates #34508