Bidirectional async sync

What it is

Edits flow both ways, asynchronously, with PostGIS as the source of truth:

• Outbound (PostGIS → AGOL): AFTER triggers write to an outbox table in the same transaction as the feature write. A standalone worker drains the outbox and pushes to AGOL via the GeoServices REST API (applyEdits, append, addFeatures, updateFeatures, deleteFeatures).
• Inbound (AGOL → PostGIS): AGOL Feature Service webhooks deliver to an inbound_queue; a worker applies them with optimistic concurrency keyed on agol_version.
• Transactional integrity: outbox writes share the feature-write transaction — if the transaction rolls back, the queued edit is cancelled too.
• Lock-safe draining: the worker reads the outbox with FOR UPDATE SKIP LOCKED.

Why it matters

Neither side blocks the other. Editors in ArcGIS Online and editors working in Postgres see their changes converge asynchronously, with explicit conflict handling rather than silent overwrites.

See it (control surface)

-- push pending outbound edits now (instead of waiting for the worker)
SELECT agol_fdw.push_outbox();

-- apply pending inbound edits delivered via webhooks
SELECT agol_fdw.apply_inbound();

-- do both, plus a reconcile audit, in one call
SELECT agol_fdw.sync_now();

Related

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