sorting - Elasticsearch分组和按嵌套字段最小值的顺序

Question

我有一个产品结构，这些产品可以在不同的商店以不同的价格购买:

[{
  "name": "SomeProduct",
  "store_prices": [
    {
      "store": "FooStore1",
      "price": 123.45
    },
    {
      "store": "FooStore2",
      "price": 345.67
    }
  ]
},{
  "name": "OtherProduct",
  "store_prices": [
    {
      "store": "FooStore1",
      "price": 456.78
    },
    {
      "store": "FooStore2",
      "price": 234.56
    }
  ]
}]

我想显示以最低价格升序排列的产品列表，以这种方式限制在10个结果中:

SomeProduct:123.45 USD

其他产品:234.56 USD

这该怎么做？我尝试了https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-nested-aggregation.html中描述的嵌套聚合方法，但它仅返回所有产品的最低价格，而不返回每种产品的最低价格:

{
  "_source": [
    "name",
    "store_prices.price"
  ],
  "query": {
    "match_all": {}
  },
  "sort": {
    "store_prices.price": "asc"
  },
  "aggs": {
    "stores": {
      "nested": {
        "path": "store_prices"
      },
      "aggs": {
        "min_price": {"min": {"field": "store_prices.price"}}
      }
    }
  },
  "from": 0,
  "size": 10
}

在SQL中，可以使用以下查询描述我要执行的操作。恐怕我在“sql中”考虑的太多了:

SELECT
  p.name,
  MIN(s.price) AS price
FROM
  products p
INNER JOIN
  store_prices s ON s.product_id = p.id
GROUP BY
  p.id
ORDER BY
  price ASC
LIMIT 10

Answer 1

您需要一个nested sorting:

{
   "query": // HERE YOUR QUERY,
   "sort": {
     "store_prices.price": {
       "order" : "asc",
       "nested_path" : "store_prices",
       "nested_filter": {
          // HERE THE FILTERS WHICH ARE EVENTUALLY 
          // FILTERING OUT SOME OF YOUR STORES
       }
     }
   }
}

请注意，您必须在嵌套过滤器字段内重复最终的嵌套查询。然后，您可以在响应的score字段中找到价格。