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Partitions & Retention

Time partitions​

Immutable tables are stored in UTC-day partitions (ts / 86_400_000). On disk:

<db>/data/t<table>/p<day>/c<channel>.seg

Partitions make three things cheap:

  • range scans touch only overlapping days,
  • retention = delete a directory,
  • late data is no special case — it merges into whichever day it belongs to (partitions are rewritable; there is no sealing window).

Mutable tables live in a single partition — their ts is a version, not an epoch to shard by.

Retention​

Declared per table, enforced by the background worker:

CREATE TABLE telemetry (speed DOUBLE) WITH (RETENTION 90 d);

Partitions older than the window are dropped whole. No row-level delete machinery exists — that is the point. Mutable tables have no retention.