diff --git a/404_Parent_Child/50_Has_child.asciidoc b/404_Parent_Child/50_Has_child.asciidoc index b448b202a..eb01e36f6 100644 --- a/404_Parent_Child/50_Has_child.asciidoc +++ b/404_Parent_Child/50_Has_child.asciidoc @@ -1,10 +1,7 @@ [[has-child]] -=== Finding Parents by Their Children - -The `has_child` query and filter can be used to find parent documents based on -the contents of their children.((("has_child query and filter")))((("parent-child relationship", "finding parents by their children"))) For instance, we could find all branches that -have employees born after 1980 with a query like this: +=== 通过子文档查询父文档 +`has_child` 的查询和过滤可以通过子文档的内容来查询父文档。((("has_child query and filter")))((("parent-child relationship", "finding parents by their children")))例如，我们根据如下查询，可查出所有80后员工所在的分公司： [source,json] ------------------------- GET /company/branch/_search @@ -24,16 +21,10 @@ GET /company/branch/_search } ------------------------- -Like the <>, the `has_child` query could -match several child documents,((("has_child query and filter", "query"))) each with a different relevance -score. How these scores are reduced to a single score for the parent document -depends on the `score_mode` parameter. The default setting is `none`, which -ignores the child scores and assigns a score of `1.0` to the parents, but it -also accepts `avg`, `min`, `max`, and `sum`. +类似于 <> ，`has_child` 查询可以匹配多个子文档((("has_child query and filter", "query")))，并且每一个子文档的评分都不同。但是由于每一个子文档都带有评分，这些评分如何规约成父文档的总得分取决于 `score_mode` 这个参数。该参数有多种取值策略：默认为 `none` ，会忽略子文档的评分，并且会给父文档评分设置为 `1.0` ； +除此以外还可以设置成 `avg` 、 `min` 、 `max` 和 `sum` 。 -The following query will return both `london` and `liverpool`, but `london` -will get a better score because `Alice Smith` is a better match than -`Barry Smith`: +下面的查询将会同时返回 `london` 和 `liverpool` ，不过由于 `Alice Smith` 要比 `Barry Smith` 更加匹配查询条件，因此 `london` 会得到一个更高的评分。 [source,json] ------------------------- @@ -53,19 +44,14 @@ GET /company/branch/_search } ------------------------- -TIP: The default `score_mode` of `none` is significantly faster than the other -modes because Elasticsearch doesn't need to calculate the score for each child -document. Set it to `avg`, `min`, `max`, or `sum` only if you care about the -score.((("parent-child relationship", "finding parents by their children", "min_children and max_children"))) +TIP: `score_mode` 为默认的 `none` 时，会显著地比其模式要快，这是因为Elasticsearch不需要计算每一个子文档的评分。只有当你真正需要关心评分结果时，才需要为 `source_mode` 设值，例如设成 `avg` 、 `min` 、 `max` 或 `sum` 。((("parent-child relationship", "finding parents by their children", "min_children and max_children"))) [[min-max-children]] -==== min_children and max_children +==== min_children 和 max_children -The `has_child` query and filter both accept the `min_children` and -`max_children` parameters,((("min_children parameter")))((("max_children parameter")))((("has_child query and filter", "min_children or max_children parameters"))) which will return the parent document only if the -number of matching children is within the specified range. +`has_child` 的查询和过滤都可以接受这两个参数：`min_children` 和 `max_children` 。 ((("min_children parameter")))((("max_children parameter")))((("has_child query and filter", "min_children or max_children parameters"))) 使用这两个参数时，只有当子文档数量在指定范围内时，才会返回父文档。 -This query will match only branches that have at least two employees: +如下查询只会返回至少有两个雇员的分公司： [source,json] ------------------------- @@ -82,21 +68,14 @@ GET /company/branch/_search } } ------------------------- -<1> A branch must have at least two employees in order to match. +<1> 至少有两个雇员的分公司才会符合查询条件。 -The performance of a `has_child` query or filter with the `min_children` or -`max_children` parameters is much the same as a `has_child` query with scoring -enabled. +带有 `min_children` 和 `max_children` 参数的 `has_child` 查询或过滤，和允许评分的 `has_child` 查询的性能非常接近。 .has_child Filter ************************** -The `has_child` filter works((("has_child query and filter", "filter"))) in the same way as the `has_child` query, except -that it doesn't support the `score_mode` parameter. It can be used only in -_filter context_—such as inside a `filtered` query--and behaves -like any other filter: it includes or excludes, but doesn't score. - -While the results of a `has_child` filter are not cached, the usual caching -rules apply to the filter _inside_ the `has_child` filter. +`has_child` 查询和过滤在运行机制上类似，((("has_child query and filter", "filter")))区别是 `has_child` 过滤不支持 `source_mode` 参数。`has_child` 过滤仅用于筛选内容--如内部的一个 `filtered` 查询--和其他过滤行为类似：包含或者排除，但没有进行评分。 +`has_child` 过滤的结果没有被缓存，但是 `has_child` 过滤内部的过滤方法适用于通常的缓存规则。 **************************