Hudi 实践 | 使用 Flink Hudi 构建流式数据湖

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摘要：本文介绍了 Flink Hudi 通过流计算对原有基于 mini-batch 的增量计算模型不断优化演进。用户可以通过 Flink SQL 将 CDC 数据实时写入 Hudi 存储，且在即将发布的 0.9 版本 Hudi 原生支持 CDC format。主要内容为：

1. 背景
2. 增量 ETL
3. 演示

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近实时

1. 分钟级别的大屏；

   
   

2. 各种 BI 分析 (OLAP)；

   
   

3. 机器学习分钟级别的特征提取。

增量计算

• 流处理的时延低，但是 SQL 的 pattern 比较固定，查询端的能力（索引、ad hoc）欠缺；

  
  

• 批处理的数仓能力丰富但是数据时延大。

核心问题

• UPSERT 能力：类似 KUDU 和 Hive ACID，Hudi 也提供了分钟级的更新能力；

  
  

• 增量消费：Hudi 通过湖存储的多 snapshots 提供增量拉取。

DB 数据入湖

• 用户既可以通过 Flink CDC connector 直接将 DB 数据导入 Hudi；

  
  

• 也可以先将 CDC 数据导入 Kafka，再通过 Kafka connector 导入 Hudi。

数据湖 CDC

• 表形态：查询最新的快照结果，同时提供高效的列存格式。

  
  

• 流形态：流式消费变更，可以指定任意点位流读之后的 changelog。

环境准备

• Flink SQL Client

  
  

• Hudi master 打包 hudi-flink-bundle jar

  
  

• Flink 1.13.1

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Flink SQL> CREATE TABLE debezium_source(>   id INT NOT NULL,>   ts BIGINT,>   name STRING,>   description STRING,>   weight DOUBLE> ) WITH (>   'connector' = 'filesystem',>   'path' = '/Users/chenyuzhao/workspace/hudi-demo/source.data',>   'format' = 'debezium-json'> );[INFO] Execute statement succeed.

Flink SQL> select * from debezium_source;+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+| op |          id |                   ts |                           name |                    description |                         weight |+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+| +I |         101 |                 1000 |                        scooter |          Small 2-wheel scooter |              3.140000104904175 || +I |         102 |                 2000 |                    car battery |                12V car battery |              8.100000381469727 || +I |         103 |                 3000 |             12-pack drill bits | 12-pack of drill bits with ... |              0.800000011920929 || +I |         104 |                 4000 |                         hammer |        12oz carpenter's hammer |                           0.75 || +I |         105 |                 5000 |                         hammer |        14oz carpenter's hammer |                          0.875 || +I |         106 |                 6000 |                         hammer |        16oz carpenter's hammer |                            1.0 || +I |         107 |                 7000 |                          rocks |          box of assorted rocks |              5.300000190734863 || +I |         108 |                 8000 |                         jacket | water resistent black wind ... |            0.10000000149011612 || +I |         109 |                 9000 |                     spare tire |             24 inch spare tire |             22.200000762939453 || -U |         106 |                 6000 |                         hammer |        16oz carpenter's hammer |                            1.0 || +U |         106 |                10000 |                         hammer |          18oz carpenter hammer |                            1.0 || -U |         107 |                 7000 |                          rocks |          box of assorted rocks |              5.300000190734863 || +U |         107 |                11000 |                          rocks |          box of assorted rocks |              5.099999904632568 || +I |         110 |                12000 |                         jacket | water resistent white wind ... |            0.20000000298023224 || +I |         111 |                13000 |                        scooter |           Big 2-wheel scooter  |              5.179999828338623 || -U |         110 |                12000 |                         jacket | water resistent white wind ... |            0.20000000298023224 || +U |         110 |                14000 |                         jacket | new water resistent white w... |                            0.5 || -U |         111 |                13000 |                        scooter |           Big 2-wheel scooter  |              5.179999828338623 || +U |         111 |                15000 |                        scooter |           Big 2-wheel scooter  |              5.170000076293945 || -D |         111 |                16000 |                        scooter |           Big 2-wheel scooter  |              5.170000076293945 |+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+Received a total of 20 rows

创建  Hudi 表，这里设置表的形态为 MERGE_ON_READ 并且打开 changelog 模式属性 changelog.enabled：

Flink SQL> CREATE TABLE hoodie_table(>   id INT NOT NULL PRIMARY KEY NOT ENFORCED,>   ts BIGINT,>   name STRING,>   description STRING,>   weight DOUBLE> ) WITH (>   'connector' = 'hudi',>   'path' = '/Users/chenyuzhao/workspace/hudi-demo/t1',>   'table.type' = 'MERGE_ON_READ',>   'changelog.enabled' = 'true',>   'compaction.async.enabled' = 'false'> );[INFO] Execute statement succeed.

查询

Flink SQL> select * from hoodie_table/*+ OPTIONS('read.streaming.enabled'='true')*/;+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+| op |          id |                   ts |                           name |                    description |                         weight |+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+| +I |         101 |                 1000 |                        scooter |          Small 2-wheel scooter |              3.140000104904175 || +I |         102 |                 2000 |                    car battery |                12V car battery |              8.100000381469727 || +I |         103 |                 3000 |             12-pack drill bits | 12-pack of drill bits with ... |              0.800000011920929 || +I |         104 |                 4000 |                         hammer |        12oz carpenter's hammer |                           0.75 || +I |         105 |                 5000 |                         hammer |        14oz carpenter's hammer |                          0.875 || +I |         106 |                 6000 |                         hammer |        16oz carpenter's hammer |                            1.0 || +I |         107 |                 7000 |                          rocks |          box of assorted rocks |              5.300000190734863 || +I |         108 |                 8000 |                         jacket | water resistent black wind ... |            0.10000000149011612 || +I |         109 |                 9000 |                     spare tire |             24 inch spare tire |             22.200000762939453 || -U |         106 |                 6000 |                         hammer |        16oz carpenter's hammer |                            1.0 || +U |         106 |                10000 |                         hammer |          18oz carpenter hammer |                            1.0 || -U |         107 |                 7000 |                          rocks |          box of assorted rocks |              5.300000190734863 || +U |         107 |                11000 |                          rocks |          box of assorted rocks |              5.099999904632568 || +I |         110 |                12000 |                         jacket | water resistent white wind ... |            0.20000000298023224 || +I |         111 |                13000 |                        scooter |           Big 2-wheel scooter  |              5.179999828338623 || -U |         110 |                12000 |                         jacket | water resistent white wind ... |            0.20000000298023224 || +U |         110 |                14000 |                         jacket | new water resistent white w... |                            0.5 || -U |         111 |                13000 |                        scooter |           Big 2-wheel scooter  |              5.179999828338623 || +U |         111 |                15000 |                        scooter |           Big 2-wheel scooter  |              5.170000076293945 || -D |         111 |                16000 |                        scooter |           Big 2-wheel scooter  |              5.170000076293945 |

Flink SQL> select * from hoodie_table;2021-08-20 20:51:25,052 INFO  org.apache.hadoop.conf.Configuration.deprecation             [] - mapred.job.map.memory.mb is deprecated. Instead, use mapreduce.map.memory.mb+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+| op |          id |                   ts |                           name |                    description |                         weight |+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+| +U |         110 |                14000 |                         jacket | new water resistent white w... |                            0.5 || +I |         101 |                 1000 |                        scooter |          Small 2-wheel scooter |              3.140000104904175 || +I |         102 |                 2000 |                    car battery |                12V car battery |              8.100000381469727 || +I |         103 |                 3000 |             12-pack drill bits | 12-pack of drill bits with ... |              0.800000011920929 || +I |         104 |                 4000 |                         hammer |        12oz carpenter's hammer |                           0.75 || +I |         105 |                 5000 |                         hammer |        14oz carpenter's hammer |                          0.875 || +U |         106 |                10000 |                         hammer |          18oz carpenter hammer |                            1.0 || +U |         107 |                11000 |                          rocks |          box of assorted rocks |              5.099999904632568 || +I |         108 |                 8000 |                         jacket | water resistent black wind ... |            0.10000000149011612 || +I |         109 |                 9000 |                     spare tire |             24 inch spare tire |             22.200000762939453 |+----+-------------+----------------------+--------------------------------+--------------------------------+--------------------------------+Received a total of 10 rows

聚合

Bounded Source 读模式下计算 count(*)：

Flink SQL> select count (*) from hoodie_table;+----+----------------------+| op |               EXPR$0 |+----+----------------------+| +I |                    1 || -U |                    1 || +U |                    2 || -U |                    2 || +U |                    3 || -U |                    3 || +U |                    4 || -U |                    4 || +U |                    5 || -U |                    5 || +U |                    6 || -U |                    6 || +U |                    7 || -U |                    7 || +U |                    8 || -U |                    8 || +U |                    9 || -U |                    9 || +U |                   10 |+----+----------------------+Received a total of 19 rows

Streaming 读模式下计算 count(*)：

Flink SQL> select count (*) from hoodie_table/*+OPTIONS('read.streaming.enabled'='true')*/;+----+----------------------+| op |               EXPR$0 |+----+----------------------+| +I |                    1 || -U |                    1 || +U |                    2 || -U |                    2 || +U |                    3 || -U |                    3 || +U |                    4 || -U |                    4 || +U |                    5 || -U |                    5 || +U |                    6 || -U |                    6 || +U |                    7 || -U |                    7 || +U |                    8 || -U |                    8 || +U |                    9 || -U |                    9 || +U |                    8 || -U |                    8 || +U |                    9 || -U |                    9 || +U |                    8 || -U |                    8 || +U |                    9 || -U |                    9 || +U |                   10 || -U |                   10 || +U |                   11 || -U |                   11 || +U |                   10 || -U |                   10 || +U |                   11 || -U |                   11 || +U |                   10 || -U |                   10 || +U |                   11 || -U |                   11 || +U |                   10 |

为给行业带来更多实时计算赋能实践的思路，鼓励广大热爱技术的开发者加深对 Flink 的掌握，Apache Flink 社区联手阿里云、英特尔、阿里巴巴人工智能治理与可持续发展实验室 (AAIG)、Occlum 联合举办 "第三届 Apache Flink 极客挑战赛暨 AAIG CUP" 活动，即日起正式启动。

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