Database Is Back but History Is Still Missing? Inspect Store-and-Forward
Restoring a database connection does not guarantee that queued history has been written successfully. Inspect backlog, throughput, and rejected records. A green connection indicator describes connectivity, not completion of recovery.
Buffer and quarantine behavior are platform-specific.
What is happening?
Store-and-forward systems buffer data and later deliver it to storage. Capacity, disk persistence, serialization, schema compatibility, and quarantine handling determine what happens during and after an outage. Data types and destinations may have separate processing paths.
Check these five things
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Record outage duration, queue size, and storage status.
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Check whether the backlog is decreasing after reconnection.
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Inspect quarantined or rejected records and their specific errors.
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Compare storage capacity and incoming rate with the recovery plan.
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Validate repaired records through supported product procedures.
Worked example
A model collects 100 records per second but forwards only 80 after recovery. Connectivity is restored, yet the queue grows by 20 records per second. Even a faster forwarding rate must exceed new arrivals enough to clear the accumulated backlog.
Quick diagnostic reference
| State | Question |
|---|---|
| Connected | Can a session open? |
| Backlog shrinking | Is recovery progressing? |
| Quarantine growing | Which records are rejected? |
The mistake to avoid
Clearing a queue may make the status look healthy by deleting evidence and unsent history. Preserve records and diagnose the rejection before choosing any authorized data-loss action.
How to verify the fix
Confirm backlog completion, resolved quarantine, and expected records across the outage interval. Document any unrecoverable gap explicitly rather than presenting a continuous chart as proof of complete history.
Field-work boundary: These are educational diagnostic guides. Use the exact equipment manuals and approved site procedures. Electrical testing and machinery changes belong to qualified, authorized personnel; control hazardous energy and validate affected functions before release.
Technical reference
Inductive Automation: Store and Forward. The examples and diagnostic tables above are original teaching material; they do not replace the product manual.