Background

We want better visibility into checkpoint duration over time so we can spot regressions and characterise checkpoint behaviour across workloads. Averages hide the tail; percentiles make slow checkpoints visible.

Goal

Create Grafana dashboards that plot checkpoint duration percentiles, sourced from the FTDC-derived WiredTiger stats.

Percentiles

Use 0.5, 0.9, 0.95 and 0.99.

Metrics

Two stats are needed because the metric was renamed over time, so both should be plotted:

quantiles(
  "quantile",
  0.50, 0.90, 0.95, 0.99,
  (mongodb.serverStatus.wiredTiger.transaction.transaction_checkpoint_most_recent_time_msecs) / 1000
)

quantiles(
  "quantile",
  0.50, 0.90, 0.95, 0.99,
  (mongodb.serverStatus.wiredTiger.checkpoint.most_recent_time_msecs) / 1000
)

Definition of Done

• Grafana dashboard(s) display p50/p90/p95/p99 of checkpoint duration (in seconds) for both metric names above.
• Dashboard link(s) shared on this ticket.