Cast milliseconds to DateTime - clickhouse

Question

I have Kafka integration objects:
CREATE TABLE topic_kafka
(
topic_data String
) ENGINE = Kafka()
SETTINGS
kafka_broker_list = 'kafka:9092',
kafka_topic_list = 'topic',
kafka_group_name = 'clickhouse_group',
kafka_format = 'JSONAsString',
kafka_num_consumers = 1;
CREATE TABLE topic
(
time DateTime64(3),
user_id Int32 NOT NULL,
version String
) ENGINE = MergeTree()
ORDER BY (user_id, time);
CREATE MATERIALIZED VIEW topic_consumer
TO topic AS
SELECT
JSONExtract(topic_data, 'time', 'Int64') as time,
toInt32(JSON_VALUE(topic_data, '$.data.user_id')) as user_id,
JSON_VALUE(topic_data, '$.data.version') as version
FROM topic_kafka;
And Kafka topic of json data with nested objects, like this:
{"time":1639387657456,"data":{"user_id":42,"version":"1.2.3"}}
The problem is that time has values 2282-12-31 00:00:00.000 in the topic table.
It also can be checked with the following query:
select cast (1639387657456 as DateTime64(3)) as dt
But for DML query below implicit date convertation works fine, as the documentation states:
insert into topic (time, user_id) values ( 1640811600000, 42)
I've found that such cast works fine too:
select cast (1639387657.456 as DateTime64(3)) as dt
Looks like I've missed something from the documentation.
What is the problem with view topic_consumer above? Is it ok to divide milliseconds by 1000 to convert it to DateTime explicitly?

Answer 1

fromUnixTimestamp64Milli
https://clickhouse.com/docs/en/sql-reference/functions/type-conversion-functions/#tounixtimestamp64nano
select fromUnixTimestamp64Milli(toInt64(1640811600000));
┌─fromUnixTimestamp64Milli(toInt64(1640811600000))─┐
│ 2021-12-29 21:00:00.000 │
└──────────────────────────────────────────────────┘