Aglet

Triage a Timezone Mismatch in Event Data

Timezone mismatches often appear as records on the wrong day, unexpected ordering near midnight, or totals that disagree across views. Triage should inventory timestamp semantics, source offsets, conversion points, and affected windows. Use concrete events near boundaries so the scope reflects real clock transitions.

Establish what is happening

  1. Inventory timestamp meaning

    List every relevant timestamp, its declared type, stored precision, offset or zone information, and intended meaning such as occurrence, ingestion, or display time. Mark fields that are date-only or derived. Do not infer a zone from a server label without checking sample values.

  2. Probe boundary events

    Collect events just before and after midnight, daylight-saving transitions, and month or reporting cutoffs. Compare their stored values, interpreted instants, local dates, and display output. Preserve the original text and the conversion rule used at each boundary.

  3. Map affected outputs

    Trace timestamp use through filters, grouping, ordering, exports, and reports. Count shifted, duplicated, or omitted events by source and date window. Separate a display-only difference from a query boundary that changes the underlying population or aggregate.

What to carry forward

Produce a bounded timezone brief with field semantics, source offsets, boundary examples, affected outputs, and the earliest differing conversion. Triage is complete when another engineer can reproduce the shifted event. Keep the zone unresolved where source metadata or intended business time is missing.

Keep the decision with the work.

Use a Work Item in Aglet to record the problem, the evidence you have, and the next decision. Add an owner and priority, then keep updates in the discussion so the next person can follow the reasoning.

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