spark-14-spark sql

作者: 西海岸虎皮猫大人 | 来源:发表于2020-10-05 18:33 被阅读0次

1.概述

shark基于spark,兼容hive,对hive依赖太强,废弃 -> spark sql
spark sql脱离hive,支持原生rdd,操作dataframe
spark on hive:
hive只存储,spark sql计算

Dataframe

相当于sql查询结果集
分布式数据容器,DataFrame底层即RDD
含数据结构信息,支持嵌套类型

数据来源

内置: json jdbc mysql hive hdfs parquet(压缩比高于json)
额外: avro(压缩) csv hbase es
es与hbase整合(重要)

谓词下推

两表join先条件过滤列裁剪

2 hello spark sql

/**
 * 不能读取嵌套格式的json,先拼成非嵌套格式
 * 读取json格式rdd
 */
public class GDataframeTest {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local").setAppName("sqltest");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);

        DataFrame json = sqlContext.read().format("json").load("./json");
        // 转rdd
        JavaRDD<Row> javaRDD = json.javaRDD();
        javaRDD.foreach(new VoidFunction<Row>() {
            public void call(Row row) throws Exception {
//                System.out.println(row);
//                System.out.println(row.get(0));
//                System.out.println(row.get(1));
                System.out.println(row.getAs("name"));
            }
        });
        // 另一种加载json的方式
//        DataFrame json = sqlContext.read().json("./json");
        // DataFrame中既有列的schema又有数据, 列按照ascii码排序
        // 写sql查询会按指定的顺序显示列
//        json.show();
//        json.printSchema();

        // select name, age from xxx where age > 18
        // 此方式不常用
/*        DataFrame df = json.select("name", "age").where(json.col("age").gt(18));
        df.show();*/
        // 显示行数
//        df.show(100);
        // 表相当于指针指向json源文件,底层操作spark job
        json.registerTempTable("t1");
        DataFrame sql = sqlContext.sql("select * from t1 where age > 18");
        sql.show();
        sc.stop();
    }
}

3 创建dataframe

反射方式将普通RDD转为DataFrame

public class IRDDToDF {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local").setAppName("RDD");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);
        JavaRDD<String> lineRDD = sc.textFile("person.txt");
        // Person需要实现序列化接口,访问级别需要是public
        // 涉及到节点传输需要序列化
        // 序列化版本号需要一致
        // driver端变量executor端拿不到的情况(无法序列化): transient修饰(拒绝反序列化) 静态变量
        final Person p = new Person();
        JavaRDD<Person> personRDD = lineRDD.map(new Function<String, Person>() {
            public Person call(String s) throws Exception {
                // Person p = new Person();
                p.setId(Integer.valueOf(s.split(",")[0]));
                p.setName(s.split(",")[1]);
                p.setAge(Integer.valueOf(s.split(",")[2]));
                return p;
            }
        });
        // 普通RDD转DataFrame,反射方式
        DataFrame df = sqlContext.applySchema(personRDD, Person.class);
        df.show();
        df.printSchema();
        df.registerTempTable("person");
        DataFrame sql = sqlContext.sql("select id, name, age from person where id = 2");
        // 按照ascii码顺序排序
        sql.show();

        JavaRDD<Row> javaRDD = df.javaRDD();
        JavaRDD<Person> map = javaRDD.map(new Function<Row, Person>() {
            public Person call(Row row) throws Exception {
                Person p = new Person();
                // 字段多时繁琐
                p.setId(Integer.valueOf(row.get(1).toString()));
                // p.setId(Integer.valueOf(row.getAs("id").toString()));
                p.setName(row.get(2).toString());
                p.setAge(Integer.valueOf((row.get(0).toString())));
                return p;
            }
        });
        map.foreach(new VoidFunction<Person>() {
            public void call(Person person) throws Exception {
                System.out.println(person.toString());
            }
        });
    }
}

动态Schema创建DataFrame

public class JDynamicSchema {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local").setAppName("RDD");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);
        JavaRDD<String> lineRDD = sc.textFile("person.txt");
        JavaRDD<Row> rowRDD = lineRDD.map(new Function<String, Row>() {
            public Row call(String s) throws Exception {
                return RowFactory.create(
                        s.split(",")[0],
                        s.split(",")[1],
                        Integer.valueOf(s.split(",")[2]));
            }
        });
        List<StructField> asList = Arrays.asList(
                DataTypes.createStructField("id", DataTypes.StringType, true),
                DataTypes.createStructField("name", DataTypes.StringType, true),
                DataTypes.createStructField("age", DataTypes.IntegerType, true)
        );
        StructType schema = DataTypes.createStructType(asList);
        DataFrame df = sqlContext.createDataFrame(rowRDD, schema);
        df.show();
    }
}

读取Parquet文件创建DF

public class KParquest {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local").setAppName("parquet");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);
        JavaRDD<String> lineRDD = sc.textFile("json");
        DataFrame df = sqlContext.read().json(lineRDD);
        df.show();
        // 创建parquet文件
        // 覆盖
        df.write().mode(SaveMode.Overwrite).format("parquet").save("parquet");
//        df.write().mode(SaveMode.Ignore).parquet("parquest");
        DataFrame load = sqlContext.read().format("parquet").load("parquet");
        load.show();
        sc.stop();
    }
}

读取mysql数据生成DF

public class LDFFromMysql {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local").setAppName("mysql");
        // 默认200分区,数据量大时可以调大
        // 聚合join时会将操作分配到响应的分区
        conf.set("spark.sql.shuffle.partitions", "1");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);
        Map<String, String> options = new HashMap<String, String>();
        options.put("url", "jdbc:mysql://127.0.0.1:3306/spark");
        options.put("driver", "com.mysql.jdbc.Driver");
        options.put("user", "root");
        options.put("password", "root");
        options.put("dbtable", "person");

        DataFrame person = sqlContext.read().format("jdbc").options(options).load();
        person.show();
        // 临时表指针指向数据库
        person.registerTempTable("person");

        // 第二种方式
        DataFrameReader reader = sqlContext.read().format("jdbc");
        reader.option("url", "jdbc:mysql://127.0.0.1:3306/spark");
        reader.option("driver", "com.mysql.jdbc.Driver");
        reader.option("user", "root");
        reader.option("password", "root");
        reader.option("dbtable", "score");
        DataFrame score = reader.load();
        score.show();
        score.registerTempTable("score");
        DataFrame result = sqlContext.sql("select person.age, score.score from person, score where person.id = score.id");
        result.show();

        // DF结果保存到mysql
        Properties properties = new Properties();
        properties.setProperty("user", "root");
        properties.setProperty("password", "root");
        result.write().mode(SaveMode.Overwrite).jdbc("jdbc:mysql://127.0.0.1:3306/spark", "result", properties);
        System.out.println("finish");

        sc.stop();
    }
}

4 spark on hive

# hive配置文件copy到spark-shell节点(node-02)
scp hive-site.xml node-02:/opt/spark/conf
# hdfs相关配置
# /opt/spark/conf/spark-env.sh
-----------
export HADOOP_HOME=/opt/hadoop
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
-----------

# hive服务端节点(node-01)开启hive
hive --service metastore
# hive客户端节点(node-03)指定hive脚本
hive
# 执行hive脚本
select count(*) from jizhan

# node-02执行spark-shell
./spark-shell --master spark://node-01:7877,node-02:7877
# 导包
import org.apache.spark.sql.hive.HiveContext
# 创建hive上下文
val hiveContext = new HiveContext(sc)
# spark执行hive sql
hiveContext.sql("select count(*) from jizhan").show()
# 与node-03 hive脚本对比可见spark执行效率明显优于hive

提交spark on hive jar

/**
 * 读取Hive中数据创建DF
 */
public class MDFFromHive {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setAppName("hive");
        JavaSparkContext sc = new JavaSparkContext(conf);
        HiveContext hiveContext = new HiveContext(sc);
        hiveContext.sql("USE spark");
        hiveContext.sql("DROP TABLE IF EXISTS student_infos");
        hiveContext.sql("CREATE TABLE IF NOT EXISTS student_infos (name STRING, age INT) row format delimited fields terminated by '\t'");
        hiveContext.sql("load data local inpath '/root/test/student_infos' into table student_infos");
        hiveContext.sql("drop table if exists student_scores");
        hiveContext.sql("CREATE TABLE IF NOT EXISTS student_scores (name STRING, score INT) row format delimited fields terminated by '\t'");
        hiveContext.sql("load data local inpath '/root/test/student_scores' into table student_scores");

        DataFrame df = hiveContext.sql("select si.name, si.age, ss.score " +
            "from student_infos si " +
            "join student_scores ss " +
            "on si.name = ss.name " +
            "where ss.score >= 80");
        df.registerTempTable("good_student");
        DataFrame result = hiveContext.sql("select * from good_student");
        result.show();

        // 结果保存到hive
        hiveContext.sql("drop table if exists result");
        df.write().mode(SaveMode.Overwrite).saveAsTable("result");
        DataFrame table = hiveContext.table("result");
        Row[] rows = table.collect();
        for(Row row : rows) {
            System.out.println(row);
        }
        sc.stop();
    }
}

导出jar文件(注意无需导出依赖的jar包),上传至node-02 /opt/spark/lib目录

# 执行spark jar
cd /opt/spark/bin
./spark-submit --master node-01:7877,node-02:7877 ../lib/test.jar

5 UDF | UDAF | 开窗函数

UDF - 用户自定义函数

public class NUDF {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local");
        conf.setAppName("udf");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);
        // 根据list创建javaRDD
        JavaRDD<String> parallelize = sc.parallelize(Arrays.asList("zhangsan","lisi","wangwu"));
        // 根据javaRDD创建rowRDD
        JavaRDD<Row> rowRDD = parallelize.map(new Function<String, Row>() {
            private static final long serialVersionUID = 1L;
            public Row call(String s) throws Exception {
                return RowFactory.create(s);
            }
        });

        /**
         * 动态创建Schema方式加载DF
         */
        List<StructField> fields = new ArrayList<StructField>();
        fields.add(DataTypes.createStructField("name", DataTypes.StringType,true));
        StructType schema = DataTypes.createStructType(fields);

        DataFrame df = sqlContext.createDataFrame(rowRDD,schema);

        df.registerTempTable("user");

        /**
         * 根据UDF函数参数的个数来决定是实现哪一个UDF  UDF1，UDF2。。。。UDF1xxx
         */
        sqlContext.udf().register("StrLen", new UDF1<String,Integer>() {
            private static final long serialVersionUID = 1L;
            public Integer call(String t1) throws Exception {
                return t1.length();
            }
        }, DataTypes.IntegerType);
        sqlContext.sql("select name ,StrLen(name) as length from user").show();

//      sqlContext.udf().register("StrLen",new UDF2<String, Integer, Integer>() {
//          private static final long serialVersionUID = 1L;
//          @Override
//          public Integer call(String t1, Integer t2) throws Exception {
//              return t1.length()+t2;
//          }
//      } ,DataTypes.IntegerType );
//      sqlContext.sql("select name ,StrLen(name,10) as length from user").show();


        sc.stop();
    }
}

UDAF - 用户自定义聚合函数

image.png

public class OUDAF {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setMaster("local").setAppName("udaf");
        JavaSparkContext sc = new JavaSparkContext(conf);
        SQLContext sqlContext = new SQLContext(sc);
        // 有可能分布在多个分区中
        JavaRDD<String> parallelize = sc.parallelize(
                Arrays.asList("zhangsan","lisi","wangwu","zhangsan","zhangsan","lisi"));
        JavaRDD<Row> rowRDD = parallelize.map(new Function<String, Row>() {
            private static final long serialVersionUID = 1L;
            public Row call(String s) throws Exception {
                return RowFactory.create(s);
            }
        });

        List<StructField> fields = new ArrayList<StructField>();
        fields.add(DataTypes.createStructField("name", DataTypes.StringType, true));
        StructType schema = DataTypes.createStructType(fields);
        // 动态schema创建dataframe
        DataFrame df = sqlContext.createDataFrame(rowRDD, schema);
        df.registerTempTable("user");
        /**
         * 注册一个UDAF函数,实现统计相同值得个数
         * 注意：这里可以自定义一个类继承UserDefinedAggregateFunction类也是可以的
         */
        sqlContext.udf().register("StringCount",new UserDefinedAggregateFunction() {
            private static final long serialVersionUID = 1L;
            /**
             * 初始化一个内部的自己定义的值,在Aggregate之前每组数据的初始化结果
             * 给每个分区的每个key做初始值(包括reduce端的每个key)
             */
            @Override
            public void initialize(MutableAggregationBuffer buffer) {
                buffer.update(0, 0);
            }
            /**
             * 更新 可以认为一个一个地将组内的字段值传递进来 实现拼接的逻辑
             * buffer.getInt(0)获取的是上一次聚合后的值
             * 相当于map端的combiner，combiner就是对每一个map task的处理结果进行一次小聚合
             * 大聚和发生在reduce端.
             * 这里即是:在进行聚合的时候，每当有新的值进来，对分组后的聚合如何进行计算
             */
            @Override
            public void update(MutableAggregationBuffer buffer, Row arg1) {
                // row即每一条数据
                // 计数,落地
                buffer.update(0, buffer.getInt(0)+1);

            }
            /**
             * 合并 update操作，可能是针对一个分组内的部分数据，在某个节点上发生的 但是可能一个分组内的数据，会分布在多个节点上处理
             * 此时就要用merge操作，将各个节点上分布式拼接好的串，合并起来
             * buffer1.getInt(0) : 大聚合的时候 上一次聚合后的值
             * buffer2.getInt(0) : 这次计算传入进来的update的结果
             * 这里即是：最后在分布式节点完成后需要进行全局级别的Merge操作
             */
            @Override
            public void merge(MutableAggregationBuffer buffer1, Row buffer2) {
                // row即map端每个分区处理后的结果
                // reduce端拉取不同节点数据聚合
                buffer1.update(0, buffer1.getInt(0) + buffer2.getInt(0));
            }
            /**
             * 在进行聚合操作的时候所要处理的数据的结果的类型
             */
            @Override
            public StructType bufferSchema() {
                return DataTypes.createStructType(Arrays.asList(DataTypes.createStructField("bffer", DataTypes.IntegerType, true)));
            }
            /**
             * 最后返回一个和dataType方法的类型要一致的类型，返回UDAF最后的计算结果
             */
            @Override
            public Object evaluate(Row row) {
                return row.getInt(0);
            }
            /**
             * 指定UDAF函数计算后返回的结果类型
             */
            @Override
            public DataType dataType() {
                return DataTypes.IntegerType;
            }
            /**
             * 指定输入字段的字段及类型
             */
            @Override
            public StructType inputSchema() {
                return DataTypes.createStructType(Arrays.asList(DataTypes.createStructField("namexxx", DataTypes.StringType, true)));
            }
            /**
             * 确保一致性 一般用true,用以标记针对给定的一组输入，UDAF是否总是生成相同的结果。
             */
            @Override
            public boolean deterministic() {
                return true;
            }

        });

        sqlContext.sql("select name ,StringCount(name) as strCount from user group by name").show();


        sc.stop();
    }
}

开窗函数

# 提交spark jar任务
./spark-submit --master spark://node-01:7877,node-02:7877 --class cn.dfun.demo.spark.PWindowFun ../lib/test.jar

/**
 * 开窗函数
 * 按照某字段分组,按照另一字段排序
 * 开窗函数需要使用hiveContext执行
 */
public class PWindowFun {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf();
        conf.setAppName("windowfun");
        conf.set("spark.sql.shuffle.partitions","1");
        JavaSparkContext sc = new JavaSparkContext(conf);
        HiveContext hiveContext = new HiveContext(sc);
        hiveContext.sql("use spark");
        hiveContext.sql("drop table if exists sales");
        hiveContext.sql("create table if not exists sales (riqi string,leibie string,jine Int) "
                + "row format delimited fields terminated by '\t'");
        hiveContext.sql("load data local inpath '/root/test/sales' into table sales");

        DataFrame result = hiveContext.sql("select riqi,leibie,jine "
                + "from ("
                + "select riqi,leibie,jine,"
                + "row_number() over (partition by leibie order by jine desc) rank " // 按照类别分组,按照金额降序排列
                + "from sales) t "
                + "where t.rank<=3");
        result.show(100);
        /**
         * 将结果保存到hive表sales_result
         */
        result.write().mode(SaveMode.Overwrite).saveAsTable("sales_result");
        sc.stop();
    }
}