kafka-connect-jdbc 不从源获取连续的时间戳

Question

我使用 kafka-connect-jdbc-4.0.0.jar 和 postgresql-9.4-1206-jdbc41.jar

kafka connect的connector配置

{
  "connector.class": "io.confluent.connect.jdbc.JdbcSourceConnector",
  "mode": "timestamp",
  "timestamp.column.name": "updated_at",
  "topic.prefix": "streaming.data.v2",
  "connection.password": "password",
  "connection.user": "user",
  "schema.pattern": "test",
  "query": "select * from view_source",
  "connection.url": "jdbc:postgresql://host:5432/test?currentSchema=test"
}

我使用 jdbc 驱动程序针对 postgresql 数据库 ("PostgreSQL 9.6.9") 配置了两个连接器，一个源和另一个接收器一切正常

我对连接器如何收集源数据有疑问，查看日志我发现在执行查询之间有 21 秒的时间差

11/1/2019 9:20:18[2019-01-11 08:20:18,985] DEBUG Checking for next block of results from TimestampIncrementingTableQuerier{name='null', query='select * from view_source', topicPrefix='streaming.data.v2', timestampColumn='updated_at', incrementingColumn='null'} (io.confluent.connect.jdbc.source.JdbcSourceTask)
11/1/2019 9:20:18[2019-01-11 08:20:18,985] DEBUG TimestampIncrementingTableQuerier{name='null', query='select * from view_source', topicPrefix='streaming.data.v2', timestampColumn='updated_at', incrementingColumn='null'} prepared SQL query: select * from view_source WHERE "updated_at" > ? AND "updated_at" < ? ORDER BY "updated_at" ASC (io.confluent.connect.jdbc.source.TimestampIncrementingTableQuerier)
11/1/2019 9:20:18[2019-01-11 08:20:18,985] DEBUG executing query select CURRENT_TIMESTAMP; to get current time from database (io.confluent.connect.jdbc.util.JdbcUtils)
11/1/2019 9:20:18[2019-01-11 08:20:18,985] DEBUG Executing prepared statement with timestamp value = 2019-01-11 08:17:07.000 end time = 2019-01-11 08:20:18.985 (io.confluent.connect.jdbc.source.TimestampIncrementingTableQuerier)
11/1/2019 9:20:19[2019-01-11 08:20:19,070] DEBUG Resetting querier TimestampIncrementingTableQuerier{name='null', query='select * from view_source', topicPrefix='streaming.data.v2', timestampColumn='updated_at', incrementingColumn='null'} (io.confluent.connect.jdbc.source.JdbcSourceTask)

11/1/2019 9:20:49[2019-01-11 08:20:49,499] DEBUG Checking for next block of results from TimestampIncrementingTableQuerier{name='null', query='select * from view_source', topicPrefix='streaming.data.v2', timestampColumn='updated_at', incrementingColumn='null'} (io.confluent.connect.jdbc.source.JdbcSourceTask)
11/1/2019 9:20:49[2019-01-11 08:20:49,500] DEBUG TimestampIncrementingTableQuerier{name='null', query='select * from view_source', topicPrefix='streaming.data.v2', timestampColumn='updated_at', incrementingColumn='null'} prepared SQL query: select * from view_source WHERE "updated_at" > ? AND "updated_at" < ? ORDER BY "updated_at" ASC (io.confluent.connect.jdbc.source.TimestampIncrementingTableQuerier)
11/1/2019 9:20:49[2019-01-11 08:20:49,500] DEBUG executing query select CURRENT_TIMESTAMP; to get current time from database (io.confluent.connect.jdbc.util.JdbcUtils)
11/1/2019 9:20:49[2019-01-11 08:20:49,500] DEBUG Executing prepared statement with timestamp value = 2019-01-11 08:20:39.000 end time = 2019-01-11 08:20:49.500 (io.confluent.connect.jdbc.source.TimestampIncrementingTableQuerier)

第一个查询收集 08:17:07.000 和 08:20:18.985 之间的数据，但第二个查询收集 08:20:39.000 和 08:20:49.500 之间的数据。两者之间有 21 秒的差异其中可能有记录...

11/1/2019 9:20:18[2019-01-11 08:20:18,985] DEBUG Executing prepared statement with timestamp value = 2019-01-11 08:17:07.000 end time = 2019-01-11 08:20:18.985 
11/1/2019 9:20:49[2019-01-11 08:20:49,500] DEBUG Executing prepared statement with timestamp value = 2019-01-11 08:20:39.000 end time = 2019-01-11 08:20:49.500

我假设其中一个数据是获得的最后一条记录，另一个值是当时的时间戳

我找不到关于这个的解释连接器是否正常工作？您是否应该假设您不会总是收集所有信息？

Answer 1

JDBC 连接器不保证检索每条消息。为此，您需要基于日志的更改数据捕获。对于由 Debezium 和 Kafka Connect 提供的 Postgres。您可以阅读更多相关信息 here.

免责声明：我在 Confluent 工作，并撰写了以上博客

编辑：这也是 ApacheCon 2020 上上述博客的录音：https://rmoff.dev/no-more-silos

kafka-connect-jdbc 不从源获取连续的时间戳

kafka-connect-jdbc does not fetch consecutive timestamp from source

postgresql

jdbc

apache-kafka

apache-kafka-connect

confluent-platform