1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
CREATE DATABASE IF NOT EXISTS common;;
USE common;;
CREATE TABLE IF NOT EXISTS common.demo_rabbitmq_entry
(
`id` UInt32,
`body` String,
`update_at` DateTime
) ENGINE = RabbitMQ
SETTINGS
rabbitmq_host_port = 'rabbitmq:5672',
rabbitmq_exchange_name = 'clickhouse-exchange',
rabbitmq_routing_key_list = 'my_routing_key',
rabbitmq_format = 'JSONEachRow',
rabbitmq_exchange_type = 'fanout',
rabbitmq_num_consumers = 1,
rabbitmq_persistent = 1,
rabbitmq_queue_base = 'demo',
rabbitmq_username = 'guest',
rabbitmq_password = 'guest';
CREATE DATABASE IF NOT EXISTS source;;
USE source;;
CREATE TABLE IF NOT EXISTS source.event (
`id` UInt32,
`body` String,
`update_at` DateTime
) ENGINE = ReplicatedReplacingMergeTree('/clickhouse/tables/source/event', '{replica}', update_at)
ORDER BY update_at;;
CREATE MATERIALIZED VIEW IF NOT EXISTS source.v_event_to_rabbitmq TO common.demo_rabbitmq_entry
AS
SELECT
"id",
"body",
"update_at"
FROM source.event;
CREATE DATABASE IF NOT EXISTS sink;;
USE sink;;
CREATE TABLE IF NOT EXISTS sink.event (
`id` UInt32,
`body` String,
`update_at` DateTime
) ENGINE = ReplicatedReplacingMergeTree('/clickhouse/tables/sink/event', '{replica}', update_at)
ORDER BY update_at;;
CREATE MATERIALIZED VIEW IF NOT EXISTS sink.v_rabbitmq_to_event TO sink.event
AS
SELECT
id AS id,
body AS body,
now() AS update_at
FROM common.demo_rabbitmq_entry;
INSERT INTO source.event
(id, body, update_at)
VALUES(1, 'foo-bar', now());
|
問題：RabbitMQ Engine 消費/推送兩個物化視圖，使用同一個來源表與目標表會發生什麼事？
解答：可以看到當到第「7」步驟後，會再次觸發上方的第「2」步驟，這將導致一個無限循環，因為訊息的循環傳遞會一直觸發。需要注意避免無限循環。
