@Arslan6and6 2016-10-10T06:50:05.000000Z 字数 7383 阅读 1333

sparkSQL

spark

一.sparkSQL中的聚合函数

//hive数据库default中存在表 emp
hive (default)> create table emp(                                                                  > empno int,
              > ename string,
              > job string,
              > mgr int,
              > hiredate string,
              > sal double,
              > comm double,
              > deptno int
              > )
              > row format delimited fields terminated by '\t';
OK
Time taken: 1.248 seconds
hive (default)> show tables;
OK
tab_name
emp
Time taken: 0.024 seconds, Fetched: 1 row(s)

[beifeng@hadoop-senior spark-1.6.1-bin-2.5.0-cdh5.3.6]$ bin/spark-shell --master local[2] --jars /opt/modules/spark-1.6.1-bin-2.5.0-cdh5.3.6/inputJars/mysql-connector-java-5.1.27-bin.jar
//查询 hive     中存在的表
scala> sqlContext.sql("show tables").show
+---------+-----------+
|tableName|isTemporary|
+---------+-----------+
|      emp|      false|
+---------+-----------+
sqlContext.sql("select * from emp").show //或者 sqlContext.read.table("emp").show
+-----+------+---------+----+----------+------+------+------+
|empno| ename|      job| mgr|  hiredate|   sal|  comm|deptno|
+-----+------+---------+----+----------+------+------+------+
| 7369| SMITH|    CLERK|7902|1980-12-17| 800.0|  null|    20|
| 7499| ALLEN| SALESMAN|7698| 1981-2-20|1600.0| 300.0|    30|
| 7521|  WARD| SALESMAN|7698| 1981-2-22|1250.0| 500.0|    30|
| 7566| JONES|  MANAGER|7839|  1981-4-2|2975.0|  null|    20|
| 7654|MARTIN| SALESMAN|7698| 1981-9-28|1250.0|1400.0|    30|
| 7698| BLAKE|  MANAGER|7839|  1981-5-1|2850.0|  null|    30|
| 7782| CLARK|  MANAGER|7839|  1981-6-9|2450.0|  null|    10|
| 7788| SCOTT|  ANALYST|7566| 1987-4-19|3000.0|  null|    20|
| 7839|  KING|PRESIDENT|null|1981-11-17|5000.0|  null|    10|
| 7844|TURNER| SALESMAN|7698|  1981-9-8|1500.0|   0.0|    30|
| 7876| ADAMS|    CLERK|7788| 1987-5-23|1100.0|  null|    20|
| 7900| JAMES|    CLERK|7698| 1981-12-3| 950.0|  null|    30|
| 7902|  FORD|  ANALYST|7566| 1981-12-3|3000.0|  null|    20|
| 7934|MILLER|    CLERK|7782| 1982-1-23|1300.0|  null|    10|
+-----+------+---------+----+----------+------+------+------+
scala> val emp_df = sqlContext.sql("select * from emp")
emp_df: org.apache.spark.sql.DataFrame = [empno: int, ename: string, job: string, mgr: int, hiredate: string, sal: double, comm: double, deptno: int]

DSL语言

1.object DataFrame 中的 agg 聚合函数

//第一种写法
emp_df.agg("sal"->"avg", "comm"->"max").show
+-----------------+---------+
|         avg(sal)|max(comm)|
+-----------------+---------+
|2073.214285714286|   1400.0|
+-----------------+---------+
//第二种写法
scala> emp_df.agg(Map("sal"->"avg", "comm"->"max")).show
+-----------------+---------+
|         avg(sal)|max(comm)|
+-----------------+---------+
|2073.214285714286|   1400.0|
+-----------------+---------+
//第三种写法 df.agg(max($"age"), avg($"salary")) 
//即 DSL全称Domain Specific Language,中文解释为领域专用语言
scala> emp_df.agg(avg($"sal"), max($"comm")).show
+-----------------+---------+
|         avg(sal)|max(comm)|
+-----------------+---------+
|2073.214285714286|   1400.0|
+-----------------+---------+
//第四种
/* df.groupBy($"department", $"gender").agg(Map(
 *     "salary" -> "avg",
 *     "age" -> "max"))
scala> emp_df.groupBy($"deptno").agg(avg($"sal"), max($"comm")).show
+------+------------------+---------+
|deptno|          avg(sal)|max(comm)|
+------+------------------+---------+
|    10|2916.6666666666665|     null|
|    20|            2175.0|     null|
|    30|1566.6666666666667|   1400.0|
+------+------------------+---------+

二、自定义函数

//注册UDF自定义函数
scala> sqlContext.udf.register(
     |     "comm_trans", //函数名
     |     (comm: Double) => {  //匿名函数
     |       if (comm.toString == "null") {
     |         0.0
     |       } else {
     |         comm
     |       }
     |     }
     | )
res22: org.apache.spark.sql.UserDefinedFunction = UserDefinedFunction(<function1>,DoubleType,List(DoubleType))
scala> sqlContext.sql("select empno, ename, sal, comm_trans(comm) cm from emp").show
+-----+------+------+------+
|empno| ename|   sal|    cm|
+-----+------+------+------+
| 7369| SMITH| 800.0|  null|
| 7499| ALLEN|1600.0| 300.0|
| 7521|  WARD|1250.0| 500.0|
| 7566| JONES|2975.0|  null|
| 7654|MARTIN|1250.0|1400.0|
| 7698| BLAKE|2850.0|  null|
| 7782| CLARK|2450.0|  null|
| 7788| SCOTT|3000.0|  null|
| 7839|  KING|5000.0|  null|
| 7844|TURNER|1500.0|   0.0|
| 7876| ADAMS|1100.0|  null|
| 7900| JAMES| 950.0|  null|
| 7902|  FORD|3000.0|  null|
| 7934|MILLER|1300.0|  null|
+-----+------+------+------+

image_1arqrs333iok1jp71unob06b89.png-85.7kB

image_1arqs2rpt1dnik8k107cih41lngm.png-82.9kB

scala> sqlContext.sql("select deptno, avg(sal) avg_sal from emp group by deptno").show
+------+------------------+
|deptno|           avg_sal|
+------+------------------+
|    10|2916.6666666666665|
|    20|            2175.0|
|    30|1566.6666666666667|
+------+------------------+

package com.ibeifeng.bigdata.spark.app.sql
import org.apache.spark.sql.Row
import org.apache.spark.sql.expressions.{MutableAggregationBuffer, UserDefinedAggregateFunction}
import org.apache.spark.sql.types._
/**
 * Created by XuanYu on 2016/8/6.
 */
object AvgSalUDAF extends UserDefinedAggregateFunction{
  /**
   * 指定输入字段的名称和类型
   */
  override def inputSchema: StructType = StructType(
    StructField("sal", DoubleType, true) :: Nil
  )
  /**
   * 更新缓冲数据的值
   * @param buffer
   * @param input
   */
  override def update(buffer: MutableAggregationBuffer, input: Row): Unit = {
    // 获取缓冲数据
    val salTotal = buffer.getDouble(0)
    val salCount = buffer.getInt(1)
    // 获取传递进来的数据
    val inputSal = input.getDouble(0)
    // 更新缓冲数据
    buffer.update(0, salTotal + inputSal)
    buffer.update(1, salCount + 1)
  }
  /**
   * 依据需求定义缓冲数据字段的名称和类型
   */
  override def bufferSchema: StructType = StructType(
    StructField("sal_total", DoubleType, true) ::
    StructField("sal_count", IntegerType, true) :: Nil
  )
  /**
   * 从字面看，是合并
   * Merges two aggregation buffers
   *  and stores the updated buffer values back to `buffer1`.
   *
   *  This is called when we merge two partially aggregated data together.
   *
   * @param buffer1
   * @param buffer2
   */
  override def merge(buffer1: MutableAggregationBuffer, buffer2: Row): Unit = {
    // 获取缓冲数据
    val salTotal1 = buffer1.getDouble(0)
    val salCount1 = buffer1.getInt(1)
    // 获取缓冲数据
    val salTotal2 = buffer2.getDouble(0)
    val salCount2 = buffer2.getInt(1)
    // 更新缓冲数据
    buffer1.update(0, salTotal1 + salTotal2)
    buffer1.update(1, salCount1 + salCount2)
  }
  /**
   * 对缓冲数据的字段值进行初始化
   * @param buffer
   */
  override def initialize(buffer: MutableAggregationBuffer): Unit = {
    buffer.update(0, 0.0)
    buffer.update(1, 0)
  }
  /**
   * 确定唯一性
   */
  override def deterministic: Boolean = true
  /**
   *
   * @param buffer
   * @return
   */
  override def evaluate(buffer: Row): Any = {
    val salTotal = buffer.getDouble(0)
    val salCount = buffer.getInt(1)
    // return
    salTotal / salCount
  }
  /**
   * 指定输出数据的类型
   */
  override def dataType: DataType = DoubleType
}

sqlContext.udf.register(
  "avg_sal",
  AvgSalUDAF
)

scala> sqlContext.sql("select deptno, avg(sal) avg_sal, avg_sal(sal) as_self from emp group by deptno").show
+------+------------------+------------------+
|deptno|           avg_sal|           as_self|
+------+------------------+------------------+
|    10|2916.6666666666665|2916.6666666666665|
|    20|            2175.0|            2175.0|
|    30|1566.6666666666667|1566.6666666666667|
+------+------------------+------------------+

import  org.apache.spark.sql.types._
Data type   Value type in Scala API to access or create a data type
ByteType    Byte    ByteType
ShortType   Short   ShortType
IntegerType Int IntegerType
LongType    Long    LongType
FloatType   Float   FloatType
DoubleType  Double  DoubleType
DecimalType java.math.BigDecimal    DecimalType
StringType  String  StringType
BinaryType  Array[Byte] BinaryType
BooleanType Boolean BooleanType
TimestampType   java.sql.Timestamp  TimestampType
DateType    java.sql.Date   DateType
ArrayType   scala.collection.Seq    ArrayType(elementType, [containsNull])
Note: The default value of containsNull is true.
MapType scala.collection.Map    MapType(keyType, valueType, [valueContainsNull])
Note: The default value of valueContainsNull is true.
StructType  org.apache.spark.sql.Row    StructType(fields)
Note: fields is a Seq of StructFields. Also, two fields with the same name are not allowed.
StructField The value type in Scala of the data type of this field (For example, Int for a StructField with the data type IntegerType)  StructField(name, dataType, nullable)

窗口函数之 ROW_NUMBER() OVER(标记条件) 标记字段

//此处ROW_NUMBER() OVER(PARTITION BY deptno ORDER BY sal DESC) rnk 的意思为给每行标记行标，标记条件为OVER()内的条件，即按照 dept 分组后按照组内的 sal 降序排列，给各个组的每行标记行号
SELECT
empno, ename, sal, deptno,
ROW_NUMBER() OVER(PARTITION BY deptno ORDER BY sal DESC) rnk
FROM
emp;
empno   ename   sal deptno  rnk
7839    KING    5000.0  10  1
7782    CLARK   2450.0  10  2
7934    MILLER  1300.0  10  3
7788    SCOTT   3000.0  20  1
7902    FORD    3000.0  20  2
7566    JONES   2975.0  20  3
7876    ADAMS   1100.0  20  4
7369    SMITH   800.0   20  5
7698    BLAKE   2850.0  30  1
7499    ALLEN   1600.0  30  2
7844    TURNER  1500.0  30  3
7521    WARD    1250.0  30  4
7654    MARTIN  1250.0  30  5
7900    JAMES   950.0   30  6

sparkSQL

一.sparkSQL中的聚合函数

1.object DataFrame 中的 agg 聚合函数

二、自定义函数

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