44 lines
1.3 KiB
Plaintext
44 lines
1.3 KiB
Plaintext
[[breaking_20_parent_child_changes]]
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=== Parent/Child changes
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Parent/child has been rewritten completely to reduce memory usage and to
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execute `has_child` and `has_parent` queries faster and more efficient. The
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`_parent` field uses doc values by default. The refactored and improved
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implementation is only active for indices created on or after version 2.0.
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In order to benefit from all the performance and memory improvements, we
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recommend reindexing all existing indices that use the `_parent` field.
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==== Parent type cannot pre-exist
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A mapping type is declared as a child of another mapping type by specifying
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the `_parent` meta field:
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[source,js]
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--------------------------
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DELETE *
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PUT my_index
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{
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"mappings": {
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"my_parent": {},
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"my_child": {
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"_parent": {
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"type": "my_parent" <1>
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}
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}
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}
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}
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--------------------------
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<1> The `my_parent` type is the parent of the `my_child` type.
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The mapping for the parent type can be added at the same time as the mapping
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for the child type, but cannot be added before the child type.
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==== `top_children` query removed
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The `top_children` query has been removed in favour of the `has_child` query.
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It wasn't always faster than the `has_child` query and the results were usually
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inaccurate. The total hits and any aggregations in the same search request
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would be incorrect if `top_children` was used.
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