Incremental sync pattern is invalid for eventually consistent cluster

[basilevs]

blog/posts/2026-03-31-mongodb-query-documents-updated-after-specific-time/README.md

Lines 113 to 133 in ef9de12

	## Incremental Sync Pattern
	A common pattern for syncing data to another system:
	```javascript
	async function syncChanges(lastSyncTime) {
	const cursor = db.collection("products").find(
	{ updatedAt: { $gt: lastSyncTime } },
	{ sort: { updatedAt: 1 } }
	);
	const changes = await cursor.toArray();
	// process changes...
	const newSyncTime = changes.length > 0
	? changes[changes.length - 1].updatedAt
	: lastSyncTime;
	return newSyncTime;
	}
	```

This will not work correclty even with Read concern: "linearizable".

What are compatible read and write concerns?