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S3 sink connector by Confluent naming and data formats

The Apache Kafka Connect® S3 sink connector enables you to move data from an Aiven for Apache Kafka® cluster to Amazon S3 for long term storage. The following document describes advanced parameters defining the naming and data formats.

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Aiven provides two version of S3 sink connector: one developed by Aiven, another developed by Confluent.

This article is about the Confluent version. Documentation for the Aiven version is available in the dedicated page.

S3 naming format​

The Apache Kafka Connect® S3 sink connector by Confluent stores a series of files as objects in the specified S3 bucket. By default, each object is named using the pattern:

topics/<TOPIC_NAME>/partition=<PARTITION_NUMBER>/<TOPIC_NAME>+<PARTITIOIN_NUMBER>+<START_OFFSET>.<FILE_EXTENSION>

The placeholders are the following:

  • TOPIC_NAME: Name of the topic to be pushed to S3
  • PARTITION_NUMBER: Topic partitions number
  • START_OFFSET: File starting offset
  • FILE_EXTENSION: The file extension depends on serialization format defined. The bin extension is generated when serializing messages in binary format.

For example, a topic with 3 partitions generates initially the following files in the destination S3 bucket:

topics/<TOPIC_NAME>/partition=0/<TOPIC_NAME>+0+0000000000.bin
topics/<TOPIC_NAME>/partition=1/<TOPIC_NAME>+1+0000000000.bin
topics/<TOPIC_NAME>/partition=2/<TOPIC_NAME>+2+0000000000.bin

S3 data format​

By default, data is stored in binary format, one line per message. The connector creates a file every X messages, where X is defined by the flush.size parameter. Setting the flush.size parameter to 1 generates a file for each message in a topic.

In the above example, having a topic with 3 partitions and 10 messages, setting the flush.size parameter to 1 generates the following files (one per message) in the destination S3 bucket:

topics/<TOPIC_NAME>/partition=0/<TOPIC_NAME>+0+0000000000.bin
topics/<TOPIC_NAME>/partition=0/<TOPIC_NAME>+0+0000000001.bin
topics/<TOPIC_NAME>/partition=0/<TOPIC_NAME>+0+0000000002.bin
topics/<TOPIC_NAME>/partition=0/<TOPIC_NAME>+0+0000000003.bin
topics/<TOPIC_NAME>/partition=1/<TOPIC_NAME>+1+0000000000.bin
topics/<TOPIC_NAME>/partition=1/<TOPIC_NAME>+1+0000000001.bin
topics/<TOPIC_NAME>/partition=1/<TOPIC_NAME>+1+0000000002.bin
topics/<TOPIC_NAME>/partition=2/<TOPIC_NAME>+2+0000000000.bin
topics/<TOPIC_NAME>/partition=2/<TOPIC_NAME>+2+0000000001.bin
topics/<TOPIC_NAME>/partition=2/<TOPIC_NAME>+2+0000000002.bin

Find additional documentation on the dedicated page.