tmq_websocket_assgnment_example.py

import taos
import taosws


def prepare():
    conn = taos.connect()
    conn.execute("drop topic if exists tmq_assignment_demo_topic")
    conn.execute("drop database if exists tmq_assignment_demo_db")
    conn.execute("create database if not exists tmq_assignment_demo_db wal_retention_period 3600")
    conn.select_db("tmq_assignment_demo_db")
    conn.execute(
        "create table if not exists tmq_assignment_demo_table (ts timestamp, c1 int, c2 float, c3 binary(10)) tags(t1 int)")
    conn.execute(
        "create topic if not exists tmq_assignment_demo_topic as select ts, c1, c2, c3 from tmq_assignment_demo_table")
    conn.execute("insert into d0 using tmq_assignment_demo_table tags (0) values (now-2s, 1, 1.0, 'tmq test')")
    conn.execute("insert into d0 using tmq_assignment_demo_table tags (0) values (now-1s, 2, 2.0, 'tmq test')")
    conn.execute("insert into d0 using tmq_assignment_demo_table tags (0) values (now, 3, 3.0, 'tmq test')")


def taosws_get_assignment_and_seek_demo():
    prepare()
    consumer = taosws.Consumer(conf={
        "td.connect.websocket.scheme": "ws",
        # should disable snapshot,
        # otherwise it will cause invalid params error
        "experimental.snapshot.enable": "false",
        "group.id": "0",
    })
    consumer.subscribe(["tmq_assignment_demo_topic"])

    # get topic assignment
    assignments = consumer.assignment()
    for assignment in assignments:
        print(assignment.to_string())

    # poll
    consumer.poll(1)
    consumer.poll(1)

    # get topic assignment again
    after_poll_assignments = consumer.assignment()
    for assignment in after_poll_assignments:
        print(assignment.to_string())

    # seek to the beginning
    for assignment in assignments:
        for a in assignment.assignments():
            consumer.seek(assignment.topic(), a.vg_id(), a.offset())

    # now the assignment should be the same as before poll
    assignments = consumer.assignment()
    for assignment in assignments:
        print(assignment.to_string())


if __name__ == '__main__':
    taosws_get_assignment_and_seek_demo()