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Add HServer cluster support
HStreamDB’s computing node HServer is designed to be stateless as a whole, so it is very suitable for rapid horizontal expansion. The HServer cluster mode of v0.6 mainly includes the following features:
- Automatic node health detection and failure recovery
- Scheduling and balancing client requests or computing tasks according to the node load conditions
Add shared-subscription mode
In the previous version, one subscription only allowed one client to consume simultaneously, which limited the client’s consumption capacity in the scenarios with a large amount of data. Therefore, in order to support the expansion of the client’s consumption capacity, HStreamDB v0.6 adds a shared-subscription mode, which allows multiple clients to consume in parallel on one subscription.
HStreamDB currently supports the “at least once” consumption semantics. After the client consumes each data, it needs to reply to the ACK. If the Ack of a certain piece of data is not received within the timeout, HServer will automatically re-deliver the data to the available consumers.
Members in the same consumer group share the consumption progress. HStream will maintain the consumption progress according to the condition of the client’s Ack. The client can resume consumption from the previous location at any time.
Add statistical function
HStreamDB v0.6 also adds a basic data statistics function to support the statistics of key indicators such as stream write rate and consumption rate. Users can view the corresponding statistical indicators through HStream CLI, as shown in the figure below.
