举个栗子说明elasticsearch 的 scripted metric aggregation

谁践踏了优雅 2023-05-29 02:03 5阅读 0赞

# 说明scripted metric aggregation 的用法。 #

POST /dd/doc/_bulk?refresh
    { "index":{ "_id":1}}
    { "name": "productA", "price": 1}
    { "index":{ "_id":2}}
    { "name": "productA", "price": 2}
    { "index":{ "_id":3}}
    { "name": "productB", "price": 3}
    { "index":{ "_id":4}}
    { "name": "productB", "price": 4}
    { "index":{ "_id":5}}
    { "name": "productC", "price": 5}
    { "index":{ "_id":6}}
    { "name": "productC", "price": 6}
    
    POST dd/_search?size=0
    { 
        "size": 0, 
        "query" : { 
            "match_all" : { }
        },
        "aggs": { 
            "profit": { 
                "scripted_metric": { 
                    "init_script" : "params._agg.transactions = []",
                    "map_script" : "params._agg.transactions.add(doc.price.value == -1 ? 0 : 2 * doc.price.value)", 
                    "combine_script" : "double profit = 0; for (t in params._agg.transactions) { profit += t } return profit",
                    "reduce_script" : "double profit = 0; for (a in params._aggs) { profit += a } return profit"
                }
            }
        }
    }
    ## 说明， 以上脚本作用，类似于sum . 
    脚本里面的语句语法是grovvy 语法， 
    init_script:  定义参数： 参数名字必须是 params.agg 开头然后跟着参数名字。 此处定义了一个数组变量transactions 
    
    map_script： 对每个分片中的每条数据，进行一样的操作。 操作在每个分片中进行。上面是在每个分片上，初始化数组。 
    
    combine_script： 同样是在每个分片中操作， 统计每个分片中，数组的和。 
    
    reduce_script： 最后把各个分片中统计的结果进行返回一个节点，然后进行求和，返回的结果，保存在params._aggs 中。
    
    ```shell
    
    # 其余例子：
    PUT /transactions/stock/_bulk?refresh
    { "index":{ "_id":1}}
    { "type": "sale","amount": 80}
    { "index":{ "_id":2}}
    { "type": "cost","amount": 10}
    { "index":{ "_id":3}}
    { "type": "cost","amount": 30}
    { "index":{ "_id":4}}
    { "type": "sale","amount": 130}
    
    如下是求盈利的总和。 
    cost 是成本
    sale 是销售价格
    
    
    POST ledger/_search?size=0
    { 
        "query" : { 
            "match_all" : { }
        },
        "aggs": { 
            "profit": { 
                "scripted_metric": { 
                    "init_script" : "params._agg.transactions = []",
                    "map_script" : "params._agg.transactions.add(doc.type.value == 'sale' ? doc.amount.value : -1 * doc.amount.value)", 
                    "combine_script" : "double profit = 0; for (t in params._agg.transactions) { profit += t } return profit",
                    "reduce_script" : "double profit = 0; for (a in params._aggs) { profit += a } return profit"
                }
            }
        }
    }