Allow reading events from a position with AppendStore::query() - #924
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The DCB spec says a store should provide a way to read events from a given starting position. AppendStore::query() always returned all matching events. query() now takes an optional `from` index (inclusive). It only limits what is read, the query itself and the append condition stay the same. This is the base for cutting off irrelevant history when building a decision model.
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DanielBadura
approved these changes
Oct 3, 2026
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The DCB spec says a store "SHOULD provide a way to read Events from a given starting Sequence Position".
AppendStore::query()always returned all matching events, so we didn't cover that yet.query()now takes an optionalfromindex, which is inclusive like in the reference implementation on dcb.events:It only limits what is read. What matches is still defined by tags and event types alone, and the append condition is unaffected. Combined with
onlyLastEvent, the last matching event is looked up first and dropped if it is beforefrom, the same in both stores.This is meant as the base for a split stream equivalent in DCB: the decision model builder looks up the last split event of a projection and reads from there, while the store doesn't need to know anything about split events.