Offset
An offset is a position or displacement measured relative to a reference point, such as within an ordered sequence, memory region, or layout.
Kafka Streams in Action, Second Edition
An offset is a nonnegative integer that identifies a record's logical position within a Kafka partition and advances sequentially as records are appended.
- How it is used
- Tracks consumer read progress and supplies the starting position for broker fetch requests.
- How deep it goes
- Defines offsets, traces fetching and commits, and descends into index-based physical record lookup.
- Examples
- Uses sequential consumer batches, offset commits, partition logs, and a Spring Kafka produce callback.
- What you can do after
- Operate/configure consumer progress by selecting fetch positions and committing processed offsets.
Read how Kafka Streams in Action, Second Edition explains offset →
Apache Kafka in Action
An offset is a position marker identifying a record's location within a Kafka partition or a connector's processed source sequence.
- How it is used
- Tracks record positions and consumer progress within Kafka partitions, and processed positions in Kafka Connect source streams.
- How deep it goes
- Explains assignment, gaps, reading positions, reset choices, and storage trade-offs without detailing an offset-management implementation.
- Examples
- Uses a console consumer reading from the beginning, a rebuilding cache, transactional database writes, and database or file source positions.
- What you can do after
- Operate/configure it: choose a starting position and an offset-storage approach suited to consumer recovery.
Kafka for Architects
A Kafka offset is a monotonically increasing integer that identifies a record's position within a partition or ordered record stream.
- How it is used
- Identifies records within partitions and tracks where consumer groups resume reading.
- How deep it goes
- Defines partition positions and elaborates commit timing, explicit positioning, lag, and failure handling without descending into broker internals.
- Examples
- Uses local-store population, out-of-order worker completion, poison records, and database update timestamps to show offset decisions.
- What you can do after
- Operate/configure consumer positioning and commits; diagnose lag or a repeatedly failing record using offsets.
Akka in Action, Second Edition
An offset is a position marker identifying how far a stream consumer has progressed through an ordered sequence of records.
- How it is used
- Tracks consumer progress so projections and Kafka streams can resume processing after restarts.
- How deep it goes
- Explains stored per-tag and per-group positions through projection tables, commits, restarts, and delivery guarantees.
- Examples
- Uses cargo journal projections with per-tag offset rows and a Kafka plain consumer printing record offsets.
- What you can do after
- Operate/configure Kafka consumers and projections to persist progress and select restart delivery behavior.
Related concepts
- strideproduced by · A stride is the step interval between successive positions or elements accessed, selected, or processed along a dimension or sequence.
- consumer groupused by · A consumer group is a logical set of message consumers that cooperatively processes a shared stream by distributing its partitions among group members.
- fetch requestused by · A fetch request is a Kafka protocol request that asks a broker to return records from a topic partition beginning at a specified offset.
- relative positioningused by · Relative positioning offsets an element from its normal position while preserving its space in normal document flow.
- __consumer_offsetspart of · __consumer_offsets is Kafka’s internal topic for storing committed offsets that record consumer groups’ reading positions.
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