db/kv, db/state: fall back to the backing tx when in-mem history is disabled - #24243
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…isabled TemporalMemBatch returns kv.ErrInMemHistoryDisabled instead of an ad-hoc error, so overlay read views can tell "no history in memory" apart from a reader failure. Both MemoryMutation and OverlayTemporalReadView treat that sentinel as a miss on GetAsOf and HistorySeek and read the backing temporal transaction; every other DomainReader error still reaches the caller.
lupin012
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September 22, 2026 20:27
lupin012
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September 22, 2026 20:27
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Closes #23500.
With in-memory history disabled,
TemporalMemBatchcannot answer historical reads. It now says sowith
kv.ErrInMemHistoryDisabledinstead of an ad-hoc error, so overlay read views can tell thatcondition apart from a reader failure:
GetAsOfandHistorySeekon bothMemoryMutationandOverlayTemporalReadViewtreat the sentinel as a miss and read the backing temporal transaction.Every other
DomainReadererror still reaches the caller.Receipt-domain reads keep coming from memory.
Note for review: for a
tsinside the not-yet-flushed window the backing transaction holds nohistory, so the fallback answers with the value as of the last flush. Restricting the fallback to
tsbelow the batch boundary would need a new accessor onTemporalMemBatch— happy to add it ifpreferred.