Spotting data gaps in history

Recognize missing inserts, feed outages, and reboot gaps in dashboard charts before they skew freeze audits.

Saved history is only as complete as the polling pipeline. Power loss at the Arduino, relay downtime, auth misconfiguration, or Supabase insert failures all leave gaps. Learning to distinguish **missing data** from **flat temperature** prevents false confidence during cold snaps and billing disputes over CSV completeness.

Chart with a visible gap versus a flat line segment labeled differently
True gaps show missing timestamps; flat segments may be valid stable readings—learn the visual difference.

Common gap causes

  1. Feed unreachable — relay down or IP change; start with stale reading debug.
  2. MCU reboot — short blank period after watchdog reset.
  3. Insert skipped — upstream fetch failed per history insert rules.
  4. Account/session — signed-out loads do not save; see session lifecycle.

Visual patterns

  • Vertical whitespace in charts when time axis jumps forward.
  • Repeated identical values can mean stuck cache—check feed caching.
  • Single-zone flat while others move suggests mapping or sensor fault.

Workflow

Cross-check live JSON with curl, then browse history dashboard. Export via CSV subscription and filter timestamp column for discontinuities—techniques in spreadsheet charting.