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场景：
需求想要实现mysql同步到clickhouse，seatunnel部署见前面文档linux环境seatunnel安装运行-CSDN博客。
官方说明文档
Clickhouse | Apache SeaTunnel
mysql同步配置
server-id=1
log_bin=/var/lib/mysql/bin.log
binlog_format=ROW
#binlog-do-db 具体要同步的数据库
binlog-do-db=gisqbpm
gtid-mode=on
enforce-gtid-consistency=on
验证MYSQL同步clckhouse
mysql数据库测试表
CREATE TABLE `test` (
`id_` varchar(255) NOT NULL,
`name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id_`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
clikhouse库测试表
-- gisqbpm.test definition
CREATE TABLE gisqbpm.test
(`id_` String,
`name` Nullable(String),
`_sign` Int8 MATERIALIZED 1,
`_version` UInt64 MATERIALIZED 1,
INDEX _version _version TYPE minmax GRANULARITY 1
)
ENGINE = ReplacingMergeTree(_version)
ORDER BY tuple(id_)
SETTINGS index_granularity = 8192;
在config中创建mysqltoclickhouse.conf
touch mysqltoclickhouse.conf配置如下
env {
execution.parallelism = 1
job.mode = "STREAMING"
checkpoint.interval = 2000
}
source {
MySQL-CDC {
base-url = "jdbc:mysql://192.168.85.128:3307/gisqbpm"
username = "root"
password = "wxy123456"
table-names = ["gisqbpm.test"]
}
}sink {
Clickhouse {
host = "192.168.85.128:8123"
database = "gisqbpm"
table = "test"
username = "default"
password = "wxy123456“
}
}
验证一：INSERT
mysql添加一条数据
INSERT INTO `gisqbpm`.`test`(`id_`, `name`) VALUES ('1', '李淳风');
select * from gisqbpm.test;
在clickhouse中也同步添加一条数据
验证二：UPDATE
mysql修改一条数据
update test set name='李淳风1' where id_='1';
select * from gisqbpm.test;
clickhouse显示如下，而是新增一个数据
验证三：DELETE
mysql删除一条数据
clickhouse发现是添加了一个数据
结论一：
这个是网上常见的案列，但都是往往写了一个添加操作就没了，奶奶个腿啊，这么多的坑竟然不说，妈的这放到生产环境不要气死人？同步时修改和删除变成添加和实际逻辑不一样。咨询了社区大佬，给我提供了一些意见，好吧那我就再验证一下
经过大佬点播，又看了一下官方文档确实有写，要通过主键去删除和更新！！！！
二：修改配置再次验证
env {
execution.parallelism = 1
job.mode = "STREAMING"
checkpoint.interval = 2000
}
source {
MySQL-CDC {
base-url = "jdbc:mysql://192.168.85.128:3307/gisqbpm"
username = "root"
password = "wxy123456"
table-names = ["gisqbpm.test"]
}
}sink {
Clickhouse {
host = "192.168.85.128:8123"
database = "gisqbpm"
table = "test"
username = "default"
password = "wxy123456"
primary_key="id_"
support_upsert=true
}
}
验证一：INSERT
mysql插入一条数据
clickhouse也同步显示添加一条数据
验证二：DELETE
mysql删除一条数据
clickhouse也同步删除一条数据
验证三：UPDATE
mysql修改一条数据
clickhouse没有变化，服务此时也挂了
错误一：
错误如下 Caused by: org.apache.seatunnel.connectors.seatunnel.clickhouse.exception.ClickhouseConnectorException: ErrorCode:[COMMON-10], ErrorDescription:[Flush data operation that in sink connector failed] - Clickhouse execute batch statement error
重启后再次执行修改操作
mysql修改一条数据
clickhouse显示是新增一条数据
结论二：
这种方式同样也是不能完美解决同步问题，修改变成了添加，而且中途服务还挂了，稳定性也有风险。
三：修改配置再次验证
env {
execution.parallelism = 1
job.mode = "STREAMING"
checkpoint.interval = 2000
}
source {
MySQL-CDC {
base-url = "jdbc:mysql://192.168.85.128:3307/gisqbpm"
username = "root"
password = "wxy123456"
table-names = ["gisqbpm.test"]
}
}sink {
Clickhouse {
host = "192.168.85.128:8123"
database = "gisqbpm"
table = "test"
username = "default"
password = "wxy123456"
primary_key="id_"
support_upsert=true
allow_experimental_lightweight_delete = true
}
}
这个是官方文档提供的配置测试一下
错误二：
Caused by: java.sql.BatchUpdateException: Code: 62. DB::Exception: Syntax error: failed at position 1 ('DELETE'): DELETE FROM "test" WHERE "id_" = '1' settings allow_experimental_lightweight_delete = true. Expected one of: Query, Query
结论三
经测试在mysql中添加一条数据，clickhouse也同步添加一条数据，但是mysql中通过主键修改一条数据，clickhouse变成添加一条数据，mysql删除一条数据，clickhosue直接报错且服务挂掉
总结：
1.seatunel同步mysql到clickhouse中存在很大的问题，生产环境如果有修改和删除操作同步到clickhouse时趁早换方案！！！
2.从操作来看seatunel对全库同步的场景也不是很友好，我100张表那就要创建100个sink对应的表非常麻烦！！
3.MaterializeMySQL的方式都比这个靠谱，至少服务不会挂！！！
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