Short definitions of the terms used across the Apache Iggy docs, with links to where each one is explained.
A one-line definition of each term, with a link to the page that explains it.
Append-only log. An ordered list of messages that only grows at the end. Messages can't be changed once written, and you can read from any earlier point to replay them. See Concepts.
Auto-commit. An option on a poll. The server saves the consumer's position as it returns the messages, before the consumer has processed them. See Polling messages.
Connection string. A single value such as iggy://user:password@localhost:8090 that tells a client how to connect. The Rust SDK and the SDKs that wrap it (Python, C++ and PHP) accept one. See Connection strings.
Consumer. A client that reads messages on its own rather than as part of a consumer group. Its position is kept separately from every other consumer's.
Consumer group. A set of consumers that share a topic's partitions, with each partition read by one member at a time. See Consumer groups.
Durability. A topic setting, replicated or persisted, that decides what must be done before a write is reported as successful. See Durability.
Offset. The position of a message within a partition, starting at 0. See Concepts.
Partition. Where a topic's messages are actually stored. A topic's messages are spread across its partitions. See Partition.
Partitioning. How a producer picks the partition for a message: a fixed partition, round robin, or a hash of a message key. See Getting started.
Payload. The body of a message. The server stores it as bytes without interpreting it, so the format is up to you. See Serialising messages.
Personal access token. A token you create on the server and use in place of a username and password, for example in a scraper or a script. See Connection strings.
Primary and replica. In a cluster, the primary orders writes and the replicas copy them. If the primary fails, the replicas elect a new one. See Viewstamped Replication.
Retention policy. Topic settings that delete old messages by age or by size. See Topic options.
Segment. Part of a partition, stored on disk as a data file and an index file. Retention deletes old segments whole. See Segment.
Shard. One thread in the server that owns a set of partitions. See Architecture.
Stream. A container for related topics. For example, a dev stream and a production stream can each have their own orders topic. See Stream.
Topic. A named set of partitions for one kind of message, such as orders or user events. See Topic.
User headers. Optional key and value pairs sent with a message, kept separate from the payload. See Serialising messages.
VSR. Viewstamped Replication, the protocol Apache Iggy uses to keep replicas in step. See Viewstamped Replication.