ES 2.4 java API aggregation API

最新推荐文章于 2024-07-07 16:23:04 发布

翻译最新推荐文章于 2024-07-07 16:23:04 发布 · 1.5k 阅读

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本文介绍了Elasticsearch中三种主要的聚合类型：Bucketing（桶）、Metric（度量）及Pipeline（管道）。Bucketing用于创建桶，每个桶关联一个键和文档标准；Metric则针对一组文档进行度量值的跟踪和计算；Pipeline则是对其他聚合及其相关度量值进行聚合。此外还提供了具体示例，如terms、date_histogram和avg聚合。

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链接地址：https://www.elastic.co/guide/en/elasticsearch/client/java-api/2.4/_bucket_aggregations.html

聚合主要有三大类：

Bucketing

A family of aggregations that build buckets, where each bucket is associated with a key and a document criterion. When the aggregation is executed, all the buckets criteria are evaluated on every document in the context and when a criterion matches, the document is considered to "fall in" the relevant bucket. By the end of the aggregation process, we’ll end up with a list of buckets - each one with a set of documents that "belong" to it.

比如：属性的值得范围，分类之类的

Metric

Aggregations that keep track and compute metrics over a set of documents.

和数学运算相关，比如：求取平均值

Pipeline

Aggregations that aggregate the output of other aggregations and their associated metrics

关联其他聚合

SearchResponse sr = node.client().prepareSearch()
    .addAggregation(
        AggregationBuilders.terms("by_country").field("country")
        .subAggregation(AggregationBuilders.dateHistogram("by_year")
            .field("dateOfBirth")
            .interval((DateHistogramInterval.YEAR)
            .subAggregation(AggregationBuilders.avg("avg_children").field("children"))
        )
    )
    .execute().actionGet();

Terms aggregation (bucket)
Date Histogram aggregation (bucket)
Average aggregation (metric)

metric Aggregation几具体操作：

max、min、sun、avg

MetricsAggregationBuilder aggregation =
        AggregationBuilders
                .avg("agg")
                .field("height");

取结果

Avg agg = sr.getAggregations().get("agg");
double value = agg.getValue();

stats包括上述的外加一个count

而extende stats 不仅包括stats还包括平法差一类的，更全面

还有百分之几，范围什么的，可以根据自己的需求再看看这一方面的介绍，metric Aggregation

Bucket aggregations

global 全局的，filter 、filters、missing 没有值或者是null的统计、terms 分类、range、date range、histogram 直方图、date histogram 等等，具体的运用看Bucket aggregation的介绍。