The query was fetching all rows for a (sandbox_id, tier) pair and
filtering by timestamp in Go. For repeatedly-paused sandboxes the
24h tier can accumulate up to 30 days of data, causing up to 120x
over-fetching for a 6h range request.
Add AND ts >= $3 to the query so Postgres filters on the primary key
(sandbox_id, tier, ts) directly. Drop the redundant Go-side loop.
Maps each user-facing range to the appropriate underlying ring buffer
tier and applies a time cutoff filter. No new ring buffers needed —
5m/10m read from the 10m tier, 1h/2h from the 2h tier, 6h/12h/24h
from the 24h tier.
Samples /proc/{fc_pid}/stat (CPU%), /proc/{fc_pid}/status (VmRSS), and
stat() on CoW files at 500ms intervals per running sandbox. Three tiered
ring buffers downsample into 30s and 5min averages for 10min/2h/24h
retention. Metrics are flushed to DB on pause (all tiers) and destroy
(24h only). New GetSandboxMetrics and FlushSandboxMetrics RPCs on the
host agent, proxied through GET /v1/sandboxes/{id}/metrics?range= on
the control plane. Returns live data for running sandboxes, DB data for
paused, and 404 for stopped.
