Is there a way to delete all the data from a topic or delete the topic before every run

Question

Is there a way to delete all the data from a topic or delete the topic before every run   Can I modify the KafkaConfig scala file to change the logRetentionHours property   Is there a way the messages gets deleted as soon as the consumer reads it   I am using producers to fetch the data from somewhere and sending the data to a particular topic where a consumer consumes  can I delete all the data from that topic on every run   I want only new data every time in the topic   Is there a way to reinitialize the topic somehow

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Tested with kafka 0 10  1  stop zookeeper  amp  Kafka server  2  then go to  kafka-logs  folder   there you will see list of kafka topic folders  delete folder with topic name 3  go to  zookeeper-data  folder   delete data inside that  4  start zookeeper  amp  kafka server again    Note   if you are deleting topic folder s inside kafka-logs but not from zookeeper-data folder  then you will see topics are still there

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As a dirty workaround  you can adjust per-topic runtime retention settings  e g  bin kafka-topics sh --zookeeper localhost 2181 --alter --topic my topic --config retention bytes 1  retention bytes 0 might also work   After a short while kafka should free the space  Not sure if this has any implications compared to re-creating the topic    ps  Better bring retention settings back  once kafka done with cleaning   You can also use retention ms to persist historical data

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We tried pretty much what the other answers are describing with moderate level of success  What really worked for us  Apache Kafka 0 8 1  is the class command  sh kafka-run-class sh kafka admin DeleteTopicCommand --topic yourtopic --zookeeper localhost 2181

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Don t think it is supported yet  Take a look at this JIRA issue  quot Add delete topic support quot   To delete manually   Shutdown the cluster Clean kafka log dir  specified by the log dir attribute in kafka config file   as well the zookeeper data Restart the cluster  For any given topic what you can do is  Stop kafka Clean kafka log specific to partition  kafka stores its log file in a format of  quot logDir topic-partition quot  so for a topic named  quot MyTopic quot  the log for partition id 0 will be stored in  tmp kafka-logs MyTopic-0 where  tmp kafka-logs is specified by the log dir attribute Restart kafka  This is NOT a good and recommended approach but it should work  In the Kafka broker config file the log retention hours per topic attribute is used to define The number of hours to keep a log file before deleting it for some specific topic  Also  is there a way the messages gets deleted as soon as the consumer reads it   From the Kafka Documentation    The Kafka cluster retains all published messages   whether or not they have been consumed   for a configurable period of time  For example if the log retention is set to two days  then for the two days after a message is published it is available for consumption  after which it will be discarded to free up space  Kafka s performance is effectively constant with respect to data size so retaining lots of data is not a problem  In fact the only metadata retained on a per-consumer basis is the position of the consumer in in the log  called the  quot offset quot   This offset is controlled by the consumer  normally a consumer will advance its offset linearly as it reads messages  but in fact the position is controlled by the consumer and it can consume messages in any order it likes  For example a consumer can reset to an older offset to reprocess   For finding the start offset to read in Kafka 0 8 Simple Consumer example they say  Kafka includes two constants to help  kafka api OffsetRequest EarliestTime   finds the beginning of the data in the logs and starts streaming from there  kafka api OffsetRequest LatestTime   will only stream new messages   You can also find the example code there for managing the offset at your consumer end      public static long getLastOffset SimpleConsumer consumer  String topic  int partition                                   long whichTime  String clientName        TopicAndPartition topicAndPartition   new TopicAndPartition topic  partition       Map lt TopicAndPartition  PartitionOffsetRequestInfo gt  requestInfo   new HashMap lt TopicAndPartition  PartitionOffsetRequestInfo gt         requestInfo put topicAndPartition  new PartitionOffsetRequestInfo whichTime  1        kafka javaapi OffsetRequest request   new kafka javaapi OffsetRequest requestInfo  kafka api OffsetRequest CurrentVersion   clientName       OffsetResponse response   consumer getOffsetsBefore request        if  response hasError              System out println  quot Error fetching data Offset Data the Broker  Reason   quot    response errorCode topic  partition             return 0            long   offsets   response offsets topic  partition       return offsets 0

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I use the utility below to cleanup after my integration test run   It uses the latest AdminZkClient api  The older api has been deprecated   import javax inject Inject import kafka zk  AdminZkClient  KafkaZkClient  import org apache kafka common utils Time  class ZookeeperUtils  Inject    config  AppConfig       val testTopic    users 1     val zkHost   config KafkaConfig zkHost   val sessionTimeoutMs   10   1000   val connectionTimeoutMs   60   1000   val isSecure   false   val maxInFlightRequests   10   val time  Time   Time SYSTEM    def cleanupTopic config  AppConfig           val zkClient   KafkaZkClient apply zkHost  isSecure  sessionTimeoutMs  connectionTimeoutMs  maxInFlightRequests  time      val zkUtils   new AdminZkClient zkClient       val pp   new Properties       pp setProperty  delete retention ms    10       pp setProperty  file delete delay ms    1000       zkUtils changeTopicConfig testTopic   pp            zkUtils deleteTopic testTopic       println  Waiting for topic to be purged  Then reset to retain records for the run       Thread sleep 60000L       val resetProps   new Properties       resetProps setProperty  delete retention ms    3000000       resetProps setProperty  file delete delay ms    4000000       zkUtils changeTopicConfig testTopic   resetProps             There is an option delete topic  But  it marks the topic for deletion  Zookeeper later deletes the topic  Since this can be unpredictably long  I prefer the retention ms approach

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As of kafka 2 3 0 version  there is an alternate way to soft deletion of Kafka  old approach are deprecated      Update retention ms to 1 sec  1000ms  then set it again after a min  to default setting i e 7 days  168 hours  604 800 000 in ms    Soft deletion -   rentention ms 1000   using kafka-configs sh   bin kafka-configs sh --zookeeper 192 168 1 10 2181 --alter --entity-name kafka topic3p3r --entity-type topics  --add-config retention ms 1000 Completed Updating config for entity  topic  kafka topic3p3r     Setting to default - 7 days  168 hours   retention ms  604800000   bin kafka-configs sh --zookeeper 192 168 1 10 2181 --alter --entity-name kafka topic3p3r --entity-type topics  --add-config retention ms 604800000

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I use this script      bin bash topics  kafka-topics --list --zookeeper zookeeper 2181  for t in  topics  do      for p in retention ms retention bytes segment ms segment bytes  do         kafka-topics --zookeeper zookeeper 2181 --alter --topic  t --config   p  100     done done sleep 60 for t in  topics  do      for p in retention ms retention bytes segment ms segment bytes  do         kafka-topics --zookeeper zookeeper 2181 --alter --topic  t --delete-config   p      done done

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In manually deleting a topic from a kafka cluster   you just might check this out https   github com darrenfu bigdata issues 6 A vital step missed a lot in most solution is in deleting the  config topics  lt topic name gt  in ZK

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As I mentioned here Purge Kafka Queue   Tested in Kafka 0 8 2  for the quick-start example  First  Add one line to server properties file under config folder   delete topic enable true   then  you can run this command   bin kafka-topics sh --zookeeper localhost 2181 --delete --topic test

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Below are scripts for emptying and deleting a Kafka topic assuming localhost as the zookeeper server and Kafka Home is set to the install directory   The script below will empty a topic by setting its retention time to 1 second and then removing the configuration      bin bash echo  Enter name of topic to empty   read topicName   Kafka Home bin kafka-configs --zookeeper localhost 2181 --alter --entity-type topics --entity-name  topicName --add-config retention ms 1000 sleep 5   Kafka Home bin kafka-configs --zookeeper localhost 2181 --alter --entity-type topics --entity-name  topicName --delete-config retention ms   To fully delete topics you must stop any applicable kafka broker s  and remove it s directory s  from the kafka log dir  default   tmp kafka-logs  and then run this script to remove the topic from zookeeper  To verify it s been deleted from zookeeper the output of ls  brokers topics should no longer include the topic       bin bash echo  Enter name of topic to delete from zookeeper   read topicName   Kafka Home bin zookeeper-shell localhost 2181  lt  lt EOF rmr  brokers topics  topicName ls  brokers topics quit EOF

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Stop ZooKeeper and Kafka              In server properties  change log retention hours value  You can comment log retention hours and add log retention ms 1000  It would keep the record on Kafka Topic for only one second    Start zookeeper and kafka     Check on consumer console  When I opened the console for the first time  record was there  But when I opened the console again  the record was removed    Later on  you can set the value of log retention hours to your desired figure

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All data about topics and its partitions are stored in tmp kafka-logs   Moreover they are stored in a format topic-partionNumber  so if you want to delete a topic newTopic  you can    stop kafka delete the files rm -rf  tmp kafka-logs newTopic-

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For brew users  If you re using brew like me and wasted a lot of time searching for the infamous kafka-logs folder  fear no more   and please do let me know if that works for you and multiple different versions of Homebrew  Kafka etc       You re probably going to find it under   Location    usr local var lib kafka-logs    How to actually find that path   this is also helpful for basically every app you install through brew   1  brew services list     kafka      started matbhz    Users matbhz Library LaunchAgents homebrew mxcl kafka plist   2  Open and read that plist you found above  3  Find the line defining server properties location open it  in my case     usr local etc kafka server properties   4  Look for the log dirs line      log dirs  usr local var lib kafka-logs   5  Go to that location and delete the logs for the topics you wish  6  Restart Kafka with brew services restart kafka

[apache-kafka] Is there a way to delete all the data from a topic or delete the topic before every run?

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