Open Spanner
Concepts

Retention

How long raw usage events are kept.

Meters can define event_retention_days. Retention controls how long raw usage events are kept for that meter.

Aggregated query results are calculated from retained events. If raw events are pruned, future queries over that old window cannot use the deleted events.

Automatic Pruning

Retention pruning runs in the API process when enabled:

OPEN_SPANNER_RETENTION_PRUNE_ENABLED=true
OPEN_SPANNER_RETENTION_PRUNE_INTERVAL=1h
OPEN_SPANNER_RETENTION_PRUNE_TIMEOUT=30m

Choose retention based on billing, audit, and reporting needs.

Query Model

How usage events become buckets.

Use Cases

Practical metering patterns you can build with Open Spanner.

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Automatic Pruning