# Concept: Sync run

A **sync run** is one execution of the pipeline for a product: fetch licences and transactions from Atlassian, check them against the expected contract (recording anomalies), synthesise the canonical lifecycle events, persist them, and deliver them to every enabled destination.

Runs are recorded in the run log with a status (`running`, `completed`, `failed`). Only **one run per product** can be `running` at a time — a database-level lock closes the race between a scheduled sync and a manual one; a second start is refused with "already running".

A run only ever looks at a narrow recent window. To load older history you use a **backfill**, which walks a long date range in resumable steps.

State is saved **only on a successful run** — a failed run leaves the previous state untouched, so it can be safely retried from where it was.

Related: [Product](/concepts/product) · [Destination](/concepts/connection)