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Replay, Backfill and Correction

How a defect discovered after the fact is corrected without taking the platform down or letting a consumer read a half-corrected table.

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Trigger
Trigger
New Derived Metric
New Derived Metric
Incident or Defect
bad enrichment logic
Incident or Defect...
Change Approval
data owner sign-off
Change Approval...
Source of truth
Source of truth
Event Hubs Retention
last 7 d
Event Hubs Retention...
Bronze Capture
ADLS · 7 y
Bronze Capture...
Offset Range Selector
by event_time
Offset Range Selector...
Replay job
Replay job
Pinned Code Version
git SHA
Pinned Code Version...
Isolated Replay Job
separate Databricks pool
Isolated Replay Job...
Shadow Checkpoint
no production offsets
Shadow Checkpoint...
Shadow write
Shadow write
Delta Shadow Branch
Delta Shadow Branch
ADX Shadow Table
_replay suffix
ADX Shadow Table...
No Consumer Reads
shadow is invisible
No Consumer Reads...
Verify
Verify
Row and Metric Reconciliation
Row and Metric Reconciliation
Variance Gate
below 0.1%
Variance Gate...
Discard and Re-run
Discard and Re-run
Cut over
Cut over
Materialized View Rebuild
Materialized View Rebuild
Atomic Table Swap
rename in ADX
Atomic Table Swap...
Consumer Notice
restated window
Consumer Notice...
variance high
variance high
re-run
re-run
Replay, Backfill and Correction
Replay, Backfill and Correction
Application we own
Application we own
Risk / gap
Risk / gap
Decision point
Decision point
Queue / topic
Queue / topic
Data store
Data store
Security / platform
Security / platform
failure / alternate
failure / alternate
Production consumers never read a shadow table; the swap is the only moment they see a change.
Production consumers never read a shadow table; the swap is the only moment they see a change.
v 1.0 · owner Platform Operations · date 2026-08
v 1.0 · owner Platform Operations · date 2026-08
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Why replay is first-class

  • Bronze retention is what turns a processing defect into a rerun instead of a data loss event
  • Replay uses a pinned code version so the correction is reproducible and auditable
  • Shadow tables mean production consumers never observe an intermediate state

Cut-over discipline

  • Reconciliation gates the swap: variance above 0.1% discards the run rather than publishing it
  • The swap is an atomic rename; materialized views rebuild behind it
  • Consumers receive a restatement notice naming the affected time window

Cost and limits

  • Replay runs on a separate compute pool so it cannot slow the live pipeline
  • A full 30-day replay is roughly 105 TB of reprocessing and is a planned activity, not an on-call one
  • Beyond 90 days the data is in archive tier and rehydration time dominates the runbook