Source ordering

Use sequenceBy to keep the newest source record when changes arrive out of order:

import { col, defineDataset } from "@sixb/core"

export const people = defineDataset("crm.people", {
  schema: [col("id", "string"), col("name", "string"), col("updatedAt", "timestamp")],
  primaryKey: "id",
  sequenceBy: "updatedAt",
})

Use the source's revision or timestamp, not fetch/receipt time. Syncs and webhooks submit complete rows or sequenced deletes:

import { change } from "@sixb/core"

change.upsert({ id: "42", name: "Sam", updatedAt: "2026-09-09T10:00:00.123Z" })
change.delete({ id: "42" }, { sequence: "2026-09-09T10:01:00.000Z" })

Merge behavior

Repeated keys are processed in submission order. Deletions retain durable ordering state, even for absent keys; new deletion state creates a version without requiring a visible row change.

Sequence values

V1 constraints

• Snapshot syncs reconcile. Returned rows become ordered upserts; omitted keys stay. Deletion requires a sequenced delete.
• Empty snapshots initialize. A first successful snapshot creates an addressable version even with no rows. Later empty snapshots reuse the existing version and retain its rows.
• Bounded retries. Sequenced writes retry known concurrency conflicts up to 3 total attempts, reusing staged changes without re-fetching. Explicit version guards stay strict.
• SQL pipeline output. SQL transforms cannot write to sequenced datasets; use a separate output dataset.
• Immutable configuration. Create a new dataset and backfill to adopt or change sequenceBy.
• Explicit derivation. Derived datasets must declare their own sequenceBy and primary key.

For content equality, object-key order is ignored; array order matters. Nullable columns treat omitted, undefined, and null equally. Integer, decimal, date, and timestamp columns use canonical values. On a sequenced dataset, every timestamp column must use a valid Date or timezone-explicit ISO string with at most 3 fractional digits, including columns other than sequenceBy. Higher precision is rejected before staging so content comparison never silently discards it.