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一、kafka的基本操作
1.1、创建topic
sh kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test
参数说明:
–create
是创建主题的的动作指令。–zookeeper
指定kafka所连接的zookeeper服务地址。–replicator-factor
指定了副本因子(即副本数量); 表示该topic需要在不同的broker中保存几份,这里设置成1,表示在两个broker中保存两份Partitions分区数。–partitions
指定分区个数;多通道,类似车道。–topic
指定所要创建主题的名称,比如test。
成功则显示:
Created topic "test".
1.2、查看topic
sh kafka-topics.sh --list --zookeeper localhost:2181
显示:
test
1.3、查看topic属性
sh kafka-topics.sh --describe --zookeeper localhost:2181 --topic test
显示:
Topic:test PartitionCount:1 ReplicationFactor:1 Configs: Topic: test Partition: 0 Leader: 0 Replicas: 0 Isr: 0
1.4、发送消息
sh kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic test
发送端输入:
>hello>where are you>let's go
1.5、消费消息
sh kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --topic test--from-beginning
消费端显示:
hellowhere are youlet's go^CProcessed a total of 3 messages
二、kafka-topics.sh 使用方式
创建、修改、删除以及查看等功能。
2.1、查看帮助
/bin目录下的每一个脚本工具,都有着众多的参数选项,不可能所有命令都记得住,这些脚本都可以使用 --help 参数来打印列出其所需的参数信息。
$ sh kafka-topics.sh --helpCommand must include exactly one action: --list, --describe, --create, --alter or --deleteOption Description ------ ----------- --alter Alter the number of partitions, replica assignment, and/or configuration for the topic. --config <String: name=value> A topic configuration override for the topic being created or altered.The following is a list of valid configurations: cleanup.policy compression.type delete.retention.ms file.delete.delay.ms flush.messages flush.ms follower.replication.throttled. replicas index.interval.bytes leader.replication.throttled.replicas max.message.bytes message.downconversion.enable message.format.version message.timestamp.difference.max.ms message.timestamp.type min.cleanable.dirty.ratio min.compaction.lag.ms min.insync.replicas preallocate retention.bytes retention.ms segment.bytes segment.index.bytes segment.jitter.ms segment.ms unclean.leader.election.enable See the Kafka documentation for full details on the topic configs. --create Create a new topic. --delete Delete a topic --delete-config <String: name> A topic configuration override to be removed for an existing topic (see the list of configurations under the --config option). --describe List details for the given topics. --disable-rack-aware Disable rack aware replica assignment --force Suppress console prompts --help Print usage information. --if-exists if set when altering or deleting topics, the action will only execute if the topic exists --if-not-exists if set when creating topics, the action will only execute if the topic does not already exist --list List all available topics. --partitions <Integer: # of partitions> The number of partitions for the topic being created or altered (WARNING: If partitions are increased for a topic that has a key, the partition logic or ordering of the messages will be affected --replica-assignment <String: A list of manual partition-to-broker broker_id_for_part1_replica1 : assignments for the topic being broker_id_for_part1_replica2 , created or altered. broker_id_for_part2_replica1 : broker_id_for_part2_replica2 , ...> --replication-factor <Integer: The replication factor for each replication factor> partition in the topic being created.--topic <String: topic> The topic to be create, alter or describe. Can also accept a regular expression except for --create option--topics-with-overrides if set when describing topics, only show topics that have overridden configs --unavailable-partitions if set when describing topics, only show partitions whose leader is not available --under-replicated-partitions if set when describing topics, only show under replicated partitions --zookeeper <String: hosts> REQUIRED: The connection string for the zookeeper connection in the form host:port. Multiple hosts can be given to allow fail-over.
2.2、副本数量规则
副本数量不能大于broker的数量。
kafka 创建主题的时候其副本数量不能大于broker的数量,否则创建主题 topic 失败。
sh kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 2 --partitions 1 --topic test1
报错:
Error while executing topic command : Replication factor: 2 larger than available brokers: 1.
[2022-11-24 14:08:18,745] ERROR org.apache.kafka.common.errors.InvalidReplicationFactorException: Replication factor: 2 larger than available brokers: 1.
(kafka.admin.TopicCommand$)
注意:副本数量和分区数量的区别。
2.3、创建主题
创建主题时候,有3个参数是必填的:
–partitions
(分区数量)、–topic
(主题名) 、–replication-factor
(复制系数),
同时还需使用 --create 参数表明本次操作是想要创建一个主题操作。
sh kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test1
返回显示:
Created topic "test1".
另外在创建主题的时候,还可以附加以下两个选项:–if-not-exists 和 --if-exists . 第一个参数表明仅当该主题不存在时候,创建; 第二个参数表明当修改或删除这个主题时候,仅在该主题存在的时候去执行操作。
2.4、查看broker上所有的主题
–list。
sh kafka-topics.sh --list --zookeeper localhost:2181
结果显示:
__consumer_offsets
test
test1
2.5、查看指定主题 topic 的详细信息
–describe。
sh kafka-topics.sh --describe --zookeeper localhost:2181 --topic test1
结果显示:
Topic:test1 PartitionCount:1 ReplicationFactor:1 Configs:
Topic: test1 Partition: 0 Leader: 0 Replicas: 0 Isr: 0
2.6、修改主题信息之增加主题分区数量
–alter。
sh kafka-topics.sh --zookeeper localhost:2181 --topic test1 --alter --partitions 2
结果显示:
WARNING: If partitions are increased for a topic that has a key, the partition logic or ordering of the messages will be affected
Adding partitions succeeded!
查看主题信息:
sh kafka-topics.sh --describe --zookeeper localhost:2181 --topic test1
可以看到已经成功的将主题的分区数量从1修改为了2。
Topic:test1 PartitionCount:2 ReplicationFactor:1 Configs: Topic: test1 Partition: 0 Leader: 0 Replicas: 0 Isr: 0 Topic: test1 Partition: 1 Leader: 0 Replicas: 0 Isr: 0
当去修改一个不存在的topic信息时(比如修改主题 test2,当前这主题是不存在的)。
sh kafka-topics.sh --zookeeper localhost:2181 --topic test2 --alter --partitions 2
会报错:
Error while executing topic command : Topic test2 does not exist on ZK path localhost:2181
[2022-11-24 14:21:33,564] ERROR java.lang.IllegalArgumentException: Topic test2 does not exist on ZK path localhost:2181
at kafka.admin.TopicCommand$.alterTopic(TopicCommand.scala:123)
at kafka.admin.TopicCommand$.main(TopicCommand.scala:65)
at kafka.admin.TopicCommand.main(TopicCommand.scala)
(kafka.admin.TopicCommand$)
注意:不要使用 --alter 去尝试减少分区的数量,如果非要减少分区的数量,只能删除整个主题 topic, 然后重新创建。
2.7、删除主题
–delete。
sh kafka-topics.sh --zookeeper localhost:2181 --delete --topic test1
日志信息提示,主题 test1已经被标记删除状态,但是若delete.topic.enable 没有设置为 true , 则将不会有任何作用。
Topic test1 is marked for deletion.
Note: This will have no impact if delete.topic.enable is not set to true.
可以测试一些:
# 一个终端启动生产者:sh kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic test1# 另一个终端启动消费者:sh kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --topic test1--from-beginning
发现此时还是可以发送消息和接收消息。如果要支持能够删除主题的操作,则需要在 /bin 的同级目录 /config目录下的文件server.properties中,修改配置delete.topic.enable=true(如果置为false,则kafka broker 是不允许删除主题的)。
然后就重启kafka:
# 停止:sh kafka-server-stop.sh -daemon ../config/server.properties# 启动:sh kafka-server-start.sh -daemon ../config/server.properties
再次删除就可以了。
sh kafka-topics.sh --zookeeper localhost:2181 --delete --topic test1
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