import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.sql.catalog.Database;
import org.apache.spark.sql.catalog.Table;

public class test18 {
    public static void main(String[] args) throws Exception {
        SparkSession spark = SparkSession
                .builder()
                .config("spark.driver.host", "localhost")
                .appName("CatalogApiTest")
                .master("local")
                .getOrCreate();

        spark.sparkContext().setLogLevel("ERROR");

        //1：数据库元数据信息
        //显示所有的数据库
        spark.catalog().listDatabases().show();
//        +-------+----------------+--------------------+
//        |   name|     description|         locationUri|
//        +-------+----------------+--------------------+
//        |default|default database|/apps/hive/warehouse|
//        +-------+----------------+--------------------+

        System.out.println("当前库:"+spark.catalog().currentDatabase());
        //当前库:default

        //获取某个数据库的信息
        Database aDefault1 = spark.catalog().getDatabase("default");
        System.out.println(aDefault1);
        //Database[name='default', description='default database', path='/apps/hive/warehouse']

        //检查某个数据库是否存在
        System.out.println("twq库是否存在:"+spark.catalog().databaseExists("twq"));
        //twq库是否存在:false

        //创建数据库
        spark.sql("CREATE DATABASE IF NOT EXISTS twq " +
                "COMMENT 'Test database' LOCATION 'hdfs://kncloud02:8020/user/oozie/oozie_test/dir8/spark-db'");

        //设置当前要操作的数据库
        spark.catalog().setCurrentDatabase("twq");

        System.out.println("当前库:"+spark.catalog().currentDatabase());
        //当前库:twq

        //2：表元数据相关信息
        //查看某个数据库中所有表信息
        spark.catalog().listTables("twq").show();
//        +----+--------+-----------+---------+-----------+
//        |name|database|description|tableType|isTemporary|
//        +----+--------+-----------+---------+-----------+
//        +----+--------+-----------+---------+-----------+

        Dataset<Row> sessionDF = spark.read().parquet(Utils.BASE_PATH + "/trackerSession");
        //创建一张表
        sessionDF.createTempView("trackerSession");
        //查看某个数据库中所有表信息
        spark.catalog().listTables("twq").show();
//        +--------------+--------+-----------+---------+-----------+
//        |          name|database|description|tableType|isTemporary|
//        +--------------+--------+-----------+---------+-----------+
//        |trackersession|    null|       null|TEMPORARY|       true|
//        +--------------+--------+-----------+---------+-----------+

        Dataset<Row> sessionRecords = spark.sql("select * from trackerSession");
        sessionRecords.show();
//        +--------------------+-------------------+-------+------------+---------+--------------------+--------------+-----------+---------------+------------+
//        |          session_id|session_server_time| cookie|cookie_label|       ip|         landing_url|pageview_count|click_count|         domain|domain_label|
//        +--------------------+-------------------+-------+------------+---------+--------------------+--------------+-----------+---------------+------------+
//        |520815c9-bdd4-40c...|2017-09-04 12:00:00|cookie1|          固执|127.0.0.3|https://www.baidu...|             1|          2|  www.baidu.com|      level1|
//        |912a4b47-6984-476...|2017-09-04 12:45:01|cookie1|          固执|127.0.0.3|https://tieba.bai...|             1|          2|tieba.baidu.com|           -|
//        |79534f7c-b4dc-4bc...|2017-09-04 12:00:01|cookie2|         有偏见|127.0.0.4|https://www.baidu...|             3|          1|  www.baidu.com|      level1|
//        +--------------------+-------------------+-------+------------+---------+--------------------+--------------+-----------+---------------+------------+

        System.out.println("log表是否存在:"+spark.catalog().tableExists("log"));
        //log表是否存在:false

        System.out.println("trackerSession表是否存在:"+spark.catalog().tableExists("trackerSession"));
        //trackerSession表是否存在:true

        //查看某个数据库中所有表信息
        Dataset<Table> aDefault = spark.catalog().listTables("default");
        aDefault.show(false);
//        +--------------+--------+-----------+---------+-----------+
//        |name          |database|description|tableType|isTemporary|
//        +--------------+--------+-----------+---------+-----------+
//        |trackersession|null    |null       |TEMPORARY|true       |
//        +--------------+--------+-----------+---------+-----------+

        //获取某个表的信息
        Table trackerSession = spark.catalog().getTable("trackerSession");
        System.out.println(trackerSession);
        //Table[name='trackerSession', tableType='TEMPORARY', isTemporary='true']

        //表的缓存
        spark.catalog().cacheTable("trackerSession");
        spark.catalog().uncacheTable("trackerSession");

        //3：表的列的元数据信息
        spark.catalog().listColumns("trackerSession").show();
//        +-------------------+-----------+--------+--------+-----------+--------+
//        |               name|description|dataType|nullable|isPartition|isBucket|
//        +-------------------+-----------+--------+--------+-----------+--------+
//        |         session_id|       null|  string|    true|      false|   false|
//        |session_server_time|       null|  string|    true|      false|   false|
//        |             cookie|       null|  string|    true|      false|   false|
//        |       cookie_label|       null|  string|    true|      false|   false|
//        |                 ip|       null|  string|    true|      false|   false|
//        |        landing_url|       null|  string|    true|      false|   false|
//        |     pageview_count|       null|     int|    true|      false|   false|
//        |        click_count|       null|     int|    true|      false|   false|
//        |             domain|       null|  string|    true|      false|   false|
//        |       domain_label|       null|  string|    true|      false|   false|
//         +-------------------+-----------+--------+--------+-----------+--------+

        spark.stop();
    }
}

有个疑问：已经设置了当前库twq，为什么表在twq和default两个库有都有，且表的database信息为null