定海区住房和城乡建设局网站如何调用网站列表页
大纲
- 可控参数
 - 字段级规则
 - 生成方式
 - 数值控制
 - 时间戳控制
 
- 表级规则
 - 生成速度
 - 生成总量
 
- 结构
 - 生成环境
 - 定义行结构
 - 定义表信息
 
- 案例
 - 随机Int型
 - 顺序Int型
 - 随机型Int数组
 - 带时间戳的多列数据
 
- 完整代码
 - 参考资料
 
在研究Flink的水位线(WaterMark)技术之前,我们可能需要Flink接收到流式数据,比如接入Kafka等。这就要求引入其他组件,增加了学习的难度。而Flink自身提供了datagen连接器,它可以用于生成流式数据,让问题内聚在Flink代码内部,从而降低学习探索的难度。
 本节我们就介绍如何使用datagen生成数据。
可控参数
我们可以使用option方法控制生成的一些规则,主要分为“字段级规则”和“表级规则”。
字段级规则
顾名思义,字段级规则是指该规则作用于具体哪个字段,这就需要指明字段的名称——fields.col_name。
生成方式
字段的生成方式由下面的字符串形式来控制(#表示字段的名称,下同)
fields.#.kind
可选值有:
- random:随机方式,比如5,2,1,4,6……。
 - sequence:顺序方式,比如1,2,3,4,5,6……。
 
数值控制
如果kind是sequence,则数值控制使用:
- fields.#.start:区间的起始值。
 - fields.#.end:区间的结束值。
 
如果配置了这个两个参数,则会生成有限个数的数据。
如果kind是random,则数值控制使用:
- fields.#.min:随机算法会选取的最小值。
 - fields.#.max:随机算法会选取的最大值。
 
时间戳控制
fields.#.max-past仅仅可以用于TIMESTAMP和TIMESTAMP_LTZ类型的数据。它表示离现在时间戳最大的时间差,这个默认值是0。TIMESTAMP和TIMESTAMP_LTZ只支持random模式生成,这就需要控制随机值的区间。如果区间太小,我们生成的时间可能非常集中。后面我们会做相关测试。
表级规则
生成速度
rows-per-second表示每秒可以生成几条数据。
生成总量
number-of-rows表示一共可以生成多少条数据。如果这个参数不设置,则表示可以生成无界流。
结构
生成环境
我们需要流式环境,而datagen是Table API的连接器,于是使用流式执行环境创建一个流式表环境。
    stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)
 
定义行结构
    schame = Schema.new_builder().column('seed', DataTypes.INT()).build()
 
这个结构以及支持的生成模式是:
| Type | Supported Generators | 
|---|---|
| BOOLEAN | random | 
| CHAR | random / sequence | 
| VARCHAR | random / sequence | 
| BINARY | random / sequence | 
| VARBINARY | random / sequence | 
| STRING | random / sequence | 
| DECIMAL | random / sequence | 
| TINYINT | random / sequence | 
| SMALLINT | random / sequence | 
| INT | random / sequence | 
| BIGINT | random / sequence | 
| FLOAT | random / sequence | 
| DOUBLE | random / sequence | 
| DATE | random | 
| TIME | random | 
| TIMESTAMP | random | 
| TIMESTAMP_LTZ | random | 
| INTERVAL YEAR TO MONTH | random | 
| INTERVAL DAY TO MONTH | random | 
| ROW | random | 
| ARRAY | random | 
| MAP | random | 
| MULTISET | random | 
定义表信息
下面这个例子就是给seed字段按随机模式,生成seed_min和seed_max之间的数值,并且每秒生成rows_per_second行。
    table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('fields.seed.min', str(seed_min)) \.option('fields.seed.max', str(seed_max)) \.option('rows-per-second', str(rows_per_second)) \.build()
 
案例
随机Int型
每秒生成5行数据,每行数据中seed字段值随机在最小值0和最大值100之间。由于没有指定number-of-rows,生成的是无界流。
def gen_random_int():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 0seed_max = 100rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.INT()).build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('fields.seed.min', str(seed_min)) \.option('fields.seed.max', str(seed_max)) \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()
 
+----+-------------+
| op |        seed |
+----+-------------+
| +I |          25 |
| +I |          28 |
| +I |          73 |
| +I |          68 |
| +I |          40 |
| +I |          55 |
| +I |           6 |
| +I |          41 |
| +I |          16 |
| +I |          19 |
……
 
顺序Int型
每秒生成5行数据,每行数据中seed字段值从1开始递增,一直自增到10。由于设置了最大和最小值,生成的是有界流。
def gen_sequence_int():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 1seed_max = 10rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.INT()).build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'sequence') \.option('fields.seed.start', str(seed_min)) \.option('fields.seed.end', str(seed_max)) \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()
 
+----+-------------+
| op |        seed |
+----+-------------+
| +I |           1 |
| +I |           2 |
| +I |           3 |
| +I |           4 |
| +I |           5 |
| +I |           6 |
| +I |           7 |
| +I |           8 |
| +I |           9 |
| +I |          10 |
+----+-------------+
10 rows in set
 
随机型Int数组
每秒生成5行数据,每行数据中seed字段是一个Int型数组,数组里面的每个元素也是随机的。
def gen_random_int_array():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.ARRAY(DataTypes.INT())) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()
 
+----+--------------------------------+
| op |                           seed |
+----+--------------------------------+
| +I | [625785630, -933999461, -48... |
| +I | [2087310154, 1602723641, 19... |
| +I | [1299442620, -613376781, -8... |
| +I | [2051511574, 246258035, -16... |
| +I | [2029482070, -1496468635, -... |
| +I | [1230213175, -1506525784, 7... |
| +I | [501476712, 1901967363, -56... |
……
 
带时间戳的多列数据
每秒生成5行数据,每行数据中seed字段值随机在最小值0和最大值100之间;timestamp字段随机在当前时间戳和“当前时间戳+max-past”之间。
def gen_random_int_and_timestamp():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 0seed_max = 100rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.INT()) \.column('timestamp', DataTypes.TIMESTAMP()) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('fields.seed.min', str(seed_min)) \.option('fields.seed.max', str(seed_max)) \.option('fields.timestamp.kind', 'random') \.option('fields.timestamp.max-past', '0') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()
 
由于max-past值为0,所以我们看到上例中每秒生成的timestamp 都极接近。
+----+-------------+----------------------------+
| op |        seed |                  timestamp |
+----+-------------+----------------------------+
| +I |          66 | 2023-11-02 13:53:29.082000 |
| +I |           9 | 2023-11-02 13:53:29.146000 |
| +I |          12 | 2023-11-02 13:53:29.146000 |
| +I |          52 | 2023-11-02 13:53:29.146000 |
| +I |          29 | 2023-11-02 13:53:29.146000 |
| +I |          63 | 2023-11-02 13:53:30.066000 |
| +I |          25 | 2023-11-02 13:53:30.066000 |
| +I |          21 | 2023-11-02 13:53:30.066000 |
| +I |          24 | 2023-11-02 13:53:30.066000 |
| +I |           6 | 2023-11-02 13:53:30.066000 |
| +I |          62 | 2023-11-02 13:53:31.067000 |
| +I |          57 | 2023-11-02 13:53:31.067000 |
| +I |          44 | 2023-11-02 13:53:31.067000 |
| +I |           6 | 2023-11-02 13:53:31.067000 |
| +I |          16 | 2023-11-02 13:53:31.067000 |
……
 
如果我们把max-past放大到比较大的数值,timestamp也将大幅度变化。
.option('fields.timestamp.max-past', '10000')
 
+----+-------------+----------------------------+
| op |        seed |                  timestamp |
+----+-------------+----------------------------+
| +I |          89 | 2023-11-02 13:57:17.342000 |
| +I |          35 | 2023-11-02 13:57:10.915000 |
| +I |          32 | 2023-11-02 13:57:11.045000 |
| +I |          74 | 2023-11-02 13:57:18.407000 |
| +I |          24 | 2023-11-02 13:57:13.603000 |
| +I |          82 | 2023-11-02 13:57:12.139000 |
| +I |          41 | 2023-11-02 13:57:16.129000 |
| +I |          95 | 2023-11-02 13:57:16.592000 |
| +I |          80 | 2023-11-02 13:57:14.364000 |
| +I |          60 | 2023-11-02 13:57:18.994000 |
| +I |          56 | 2023-11-02 13:57:19.330000 |
| +I |          10 | 2023-11-02 13:57:18.876000 |
| +I |          43 | 2023-11-02 13:57:12.449000 |
| +I |          73 | 2023-11-02 13:57:13.183000 |
| +I |          17 | 2023-11-02 13:57:18.736000 |
| +I |          46 | 2023-11-02 13:57:21.368000 |
……
 
完整代码
from pyflink.datastream import StreamExecutionEnvironment,RuntimeExecutionMode
from pyflink.table import StreamTableEnvironment, TableDescriptor, Schema, DataTypesdef gen_random_int():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 0seed_max = 100rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.INT()).build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('fields.seed.min', str(seed_min)) \.option('fields.seed.max', str(seed_max)) \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_sequence_int():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 1seed_max = 10rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.INT()).build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'sequence') \.option('fields.seed.start', str(seed_min)) \.option('fields.seed.end', str(seed_max)) \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_sequence_string():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 0seed_max = 100rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.STRING()).build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'sequence') \.option('fields.seed.start', str(seed_min)) \.option('fields.seed.end', str(seed_max)) \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_random_char():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.CHAR(4)).build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_random_int_and_timestamp():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)seed_min = 0seed_max = 100rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.INT()) \.column('timestamp', DataTypes.TIMESTAMP()) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('fields.seed.min', str(seed_min)) \.option('fields.seed.max', str(seed_max)) \.option('fields.timestamp.kind', 'random') \.option('fields.timestamp.max-past', '10000') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_random_int_array():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.ARRAY(DataTypes.INT())) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_random_map():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.MAP(DataTypes.STRING(), DataTypes.INT())) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_random_multiset():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.MULTISET(DataTypes.STRING())) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()def gen_random_row():stream_execute_env = StreamExecutionEnvironment.get_execution_environment()stream_execute_env.set_runtime_mode(RuntimeExecutionMode.STREAMING)stream_table_env = StreamTableEnvironment.create(stream_execution_environment=stream_execute_env)rows_per_second = 5schame = Schema.new_builder().column('seed', DataTypes.ROW([DataTypes.FIELD("id", DataTypes.BIGINT()), DataTypes.FIELD("data", DataTypes.STRING())])) \.build()table_descriptor = TableDescriptor.for_connector('datagen') \.schema(schame) \.option('fields.seed.kind', 'random') \.option('rows-per-second', str(rows_per_second)) \.build()stream_table_env.create_temporary_table('source', table_descriptor)table = stream_table_env.from_path('source')table.execute().print()if __name__ == '__main__':gen_random_int_and_timestamp()
 
参考资料
- https://nightlies.apache.org/flink/flink-docs-release-1.19/docs/connectors/table/datagen/
 
