> ## Documentation Index > Fetch the complete documentation index at: https://docs.causeloop.ai/llms.txt > Use this file to discover all available pages before exploring further. # Trigger Backfill > Trigger a REAL backfill sync run for a connector. Task LB4: this used to return a fake "queued" job with a made-up `estimated_completion` timestamp -- nothing ever executed, `progress` never advanced past 0.0, and `result_url` was always null. Replaced with the exact same real-execution path `POST /connectors/{id}/sync` uses (`run_sync()` via `services/connector_sync.py`), just with `trigger="backfill"` and an explicit `since` override instead of `trigger="manual"`'s cursor-based incremental read. The response IS the real `sync_run` record (same shape `trigger_sync` returns) -- no separate "job" concept, no fabricated ETA. It's immediately queryable via `GET .../sync-runs` (this run appears with `trigger="backfill"`) and `GET .../sync-runs/{run_id}`, and on failure (e.g. SSRF-blocked or unreachable DSN) the run is persisted with `status="failed"` and a real `error` -- never a fake queued success. since-semantics: the historical window comes from the connector's own `backfill_days` config (set at `POST /connectors` time, default 30 -- see `ConnectorCreate`/`allowed_fields` above), not a request body -- there's nothing left for a caller to override, so the endpoint takes no body. `backfill_days` (1..730 per `_validate_backfill_days`) -> `since = now - backfill_days` (an explicit lower bound that OVERRIDES `last_synced_at` for this one run -- see `run_sync`'s docstring for why a backfill intentionally re-walks a window that may predate the cursor). Missing/`None`/`0` (a legacy connector predating this validation, or an explicit "unset" 0) resolves to the documented create-time default of 30 days, NOT a full/unbounded read: an unbounded historical read is NOT reachable via this endpoint (contrast `db_adapter.db_fetch_rows`'s own "None -> full read" semantics, which apply only when a provider is called directly with `since=None` -- this handler never passes that through). Out-of-range/non-numeric stored values are defensively clamped into [1, 730] with a warning; they should never occur post-validation but stored data can predate it. ## OpenAPI ````yaml /openapi.json post /v1/connectors/{connector_id}/backfill openapi: 3.1.0 info: description: Causeloop Platform Backend title: Causeloop API version: 1.0.0 servers: [] security: [] paths: /v1/connectors/{connector_id}/backfill: post: tags: - connectors summary: Trigger Backfill description: >- Trigger a REAL backfill sync run for a connector. Task LB4: this used to return a fake "queued" job with a made-up `estimated_completion` timestamp -- nothing ever executed, `progress` never advanced past 0.0, and `result_url` was always null. Replaced with the exact same real-execution path `POST /connectors/{id}/sync` uses (`run_sync()` via `services/connector_sync.py`), just with `trigger="backfill"` and an explicit `since` override instead of `trigger="manual"`'s cursor-based incremental read. The response IS the real `sync_run` record (same shape `trigger_sync` returns) -- no separate "job" concept, no fabricated ETA. It's immediately queryable via `GET .../sync-runs` (this run appears with `trigger="backfill"`) and `GET .../sync-runs/{run_id}`, and on failure (e.g. SSRF-blocked or unreachable DSN) the run is persisted with `status="failed"` and a real `error` -- never a fake queued success. since-semantics: the historical window comes from the connector's own `backfill_days` config (set at `POST /connectors` time, default 30 -- see `ConnectorCreate`/`allowed_fields` above), not a request body -- there's nothing left for a caller to override, so the endpoint takes no body. `backfill_days` (1..730 per `_validate_backfill_days`) -> `since = now - backfill_days` (an explicit lower bound that OVERRIDES `last_synced_at` for this one run -- see `run_sync`'s docstring for why a backfill intentionally re-walks a window that may predate the cursor). Missing/`None`/`0` (a legacy connector predating this validation, or an explicit "unset" 0) resolves to the documented create-time default of 30 days, NOT a full/unbounded read: an unbounded historical read is NOT reachable via this endpoint (contrast `db_adapter.db_fetch_rows`'s own "None -> full read" semantics, which apply only when a provider is called directly with `since=None` -- this handler never passes that through). Out-of-range/non-numeric stored values are defensively clamped into [1, 730] with a warning; they should never occur post-validation but stored data can predate it. operationId: trigger_backfill_v1_connectors__connector_id__backfill_post parameters: - in: path name: connector_id required: true schema: title: Connector Id type: string responses: '202': content: application/json: schema: {} description: Successful Response '422': content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' description: Validation Error security: - HTTPBearer: [] components: schemas: HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' title: Detail type: array title: HTTPValidationError type: object ValidationError: properties: ctx: title: Context type: object input: title: Input loc: items: anyOf: - type: string - type: integer title: Location type: array msg: title: Message type: string type: title: Error Type type: string required: - loc - msg - type title: ValidationError type: object securitySchemes: HTTPBearer: scheme: bearer type: http ````