Function getOrCreateTableSnapshot

apps/sim/lib/table/snapshot-cache.ts:152–188

(
  table: TableDefinition,
  requestId: string
)

 * across the upload. Concurrent misses write the same version-pinned key (idempotent).
 */
export async function getOrCreateTableSnapshot(
  table: TableDefinition,
  requestId: string
): Promise<TableSnapshotRef> {
  const shapeHash = schemaFingerprint(table)
  const version = await readRowsVersion(table.id)
  const key = snapshotKey(table.workspaceId, table.id, version, shapeHash)

  const head = await headObject(key, SNAPSHOT_STORAGE_CONTEXT)
  if (head) {
    logger.info(`[${requestId}] Snapshot hit`, { tableId: table.id, version, size: head.size })
    return { key, size: head.size, version }
  }

  logger.info(`[${requestId}] Snapshot miss; materializing`, { tableId: table.id, version })
  const size = await materialize(table, key)

  const after = await readRowsVersion(table.id)
  if (after !== version) {
    // The table mutated mid-scan: the bytes under `key` may be torn. Re-key to the new version and
    // rebuild once (or reuse if a concurrent writer already stored it); drop the stale object.
    logger.info(`[${requestId}] rows_version advanced during materialize; re-keying`, {
      tableId: table.id,
      from: version,
      to: after,
    })
    const newKey = snapshotKey(table.workspaceId, table.id, after, shapeHash)
    const newHead = await headObject(newKey, SNAPSHOT_STORAGE_CONTEXT)
    const newSize = newHead ? newHead.size : await materialize(table, newKey)
    await deleteFile({ key, context: SNAPSHOT_STORAGE_CONTEXT }).catch(() => {})
    void deletePreviousVersion(table, after, shapeHash)
    return { key: newKey, size: newSize, version: after }
  }

  void deletePreviousVersion(table, version, shapeHash)
  return { key, size, version }
}