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This KIP dives deeper into the idea of Shareable State Stores, the ability to use data within a state store across multiple applications without duplicating it on topic level.

Status

Current state: Under DiscussionAccepted

Discussion thread: https://lists.apache.org/thread/n0rbdpbwn9p92xd6mn5m73tlmbqp1627

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addReadOnlyStateStore(final StoreBuilder<?> storeBuilder,
                      final String sourceName,
                      final TimestampExtractor timestampExtractor,
                      final Deserializer<KIn> keyDeserializer,
                      final Deserializer<VIn> valueDeserializer,
                      final String topic,
                      final String processorName,
                      final ProcessorSupplier<KIn, VIn, Void, Void> stateUpdateSupplier)

The method signature is aligned with the one for adding global state stores. Similarly, there is an overloaded method which doesn't take the TimestampExtractor:

addReadOnlyStateStore(final StoreBuilder<?> storeBuilder,
                      final String sourceName timestampExtractor,
                      final Deserializer<KIn> keyDeserializer,
                      final Deserializer<VIn> valueDeserializer,
                      final String topic,
                      final String processorName,
                      final ProcessorSupplier<KIn, VIn, Void, Void> stateUpdateSupplier)

This method The first method would be a wrapper around the following calls:

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Logging on the passed-in StoreBuilder will be disabled to prevent changes to the compacted topic.

The source name is constructed as <store_name>-readonly-log 

The processor name is constructed as <store_name>-processor 

Compatibility, Deprecation, and Migration Plan

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