flink-python/pyflink/examples/table/windowing/over_window.py

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import logging
import sys

from pyflink.common.time import Instant

from pyflink.common import Types
from pyflink.datastream import StreamExecutionEnvironment
from pyflink.table import (DataTypes, TableDescriptor, Schema, StreamTableEnvironment)
from pyflink.table.expressions import col, row_interval, CURRENT_ROW
from pyflink.table.window import Over


def tumble_window_demo():
    env = StreamExecutionEnvironment.get_execution_environment()
    env.set_parallelism(1)
    t_env = StreamTableEnvironment.create(stream_execution_environment=env)

    # define the source with watermark definition
    ds = env.from_collection(
        collection=[
            (Instant.of_epoch_milli(1000), 'Alice', 110.1),
            (Instant.of_epoch_milli(4000), 'Bob', 30.2),
            (Instant.of_epoch_milli(3000), 'Alice', 20.0),
            (Instant.of_epoch_milli(2000), 'Bob', 53.1),
            (Instant.of_epoch_milli(5000), 'Alice', 13.1),
            (Instant.of_epoch_milli(3000), 'Bob', 3.1),
            (Instant.of_epoch_milli(7000), 'Bob', 16.1),
            (Instant.of_epoch_milli(10000), 'Alice', 20.1)
        ],
        type_info=Types.ROW([Types.INSTANT(), Types.STRING(), Types.FLOAT()]))

    table = t_env.from_data_stream(
        ds,
        Schema.new_builder()
              .column_by_expression("ts", "CAST(f0 AS TIMESTAMP(3))")
              .column("f1", DataTypes.STRING())
              .column("f2", DataTypes.FLOAT())
              .watermark("ts", "ts - INTERVAL '3' SECOND")
              .build()
    ).alias("ts", "name", "price")

    # define the sink
    t_env.create_temporary_table(
        'sink',
        TableDescriptor.for_connector('print')
                       .schema(Schema.new_builder()
                               .column('name', DataTypes.STRING())
                               .column('total_price', DataTypes.FLOAT())
                               .build())
                       .build())

    # define the over window operation
    table = table.over_window(
        Over.partition_by(col("name"))
            .order_by(col("ts"))
            .preceding(row_interval(2))
            .following(CURRENT_ROW)
            .alias('w')) \
        .select(col('name'), col('price').max.over(col('w')))

    # submit for execution
    table.execute_insert('sink') \
         .wait()
    # remove .wait if submitting to a remote cluster, refer to
    # https://nightlies.apache.org/flink/flink-docs-stable/docs/dev/python/faq/#wait-for-jobs-to-finish-when-executing-jobs-in-mini-cluster
    # for more details


if __name__ == '__main__':
    logging.basicConfig(stream=sys.stdout, level=logging.INFO, format="%(message)s")

    tumble_window_demo()