下面是一个使用Flink计算count distinct的Java代码示例: importorg.apache.flink.api.common.functions.AggregateFunction;importorg.apache.flink.api.java.tuple.Tuple2;publicclassCountDistinctimplementsAggregateFunction<Tuple2<String,Integer>,Tuple2<Integer,HashSet<String>>,Integer>{@OverridepublicTuple2<Integer,Ha...
java stream distinct count 报空指针 一、概述 为了避免编写代码的时出现很多的空指针异常。在很多情况下我们都需要做各种非空的判断。 比如如下代码: // 用户对象先获取地址对象,再用地址对象获取省的值 user.getAddress().getProvince(); 1. 2. 如果user为null或者user.getAddress()为null的时候,就会报空指...
一、需求:select count(distinct city_name) from tableA; 二、代码:用的是cardinality基数统计,高版本API 1 AggregationBuilders.cardinality(field).field(field);// 第一个field是聚合的别名,别名就是下面根据这个别名获取聚合结果 第二个是ES里的字段 1/**2* 查询去重后总量3*@paramreq4*@paramfield es里...
Thedistinct()method returns a stream of unique elements. It is a stateful intermediate operation and returns a new stream. This method useshashCode()andequals()to get the unique elements Thesorted()method returns a stream consisting of elements in the sorted natural order. This method can also ...
Step 1 - List unique distinct values The UNIQUE function returns a unique or unique distinct list. Function syntax: UNIQUE(array,[by_col],[exactly_once]) UNIQUE(B3:B8) returns {"France";"Germany";"Italy"} Step 2 - Count nonempty values in array The COUNTA function counts the non-empty...
异常描述:使用分页插件进行分页查询并去重。生成的SQL语句异常,DISTINCT 应拼接在 SELECT 关键字后,而不应该拼接在查询字段中(查看以下SQL3)。 Java 代码: 分页: Page<SysUser> sysUserPage = sysUserDao.getBaseMapper() .selectJoinPage( new Page<SysUser>(pageable.getIndex(), pageable.getSize()).setOpti...
("APPROX_COUNT_DISTINCT," + "ARRAY_AGG," + "AVG," + "BIT_" + //"BIT_AND," + //"BIT_OR," + //"BIT_XOR," + "BOOL_," + //"BOOL_AND," + //"BOOL_OR," + "CHECKSUM_AGG," + "COLLECT," + "CORR," + //"CORR_," + //"CORRELATION," + "COUNT," + //"COUNT_BI...
ES中对应的SQL的count（distinct列名）java实现⼀、需求：select count(distinct city_name) from tableA;⼆、代码：⽤的是cardinality基数统计，⾼版本API AggregationBuilders.cardinality(field).field(field); // 第⼀个field是聚合的别名，别名就是下⾯根据这个别名获取聚合结果第⼆个是ES⾥的字段 ...
public class DataStreamJob { public static void main(String[] args) throws Exception { final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env); DataStream<String> dataStream = env.fromElements("Alice",...
This method returns the count of elements in this stream. This is a special case of a reduction and is equivalent to: mapToLong(e > 1L).sum()This is a terminal operation.Examples package com.logicbig.example.intstream;import java.util.stream.IntStream;public class CountExample { public ...