const reader = new DocumentClientQueryReadable(
  new DocumentClient(), {
  TableName: 'someTable',
  KeyConditionExpression: 'key = :primaryKey',
  ExpressionAttributeValues: {
    ':primaryKey': 'someValue'
  }
})
const transformOutput = new Transform({
  objectMode: true,
  transform (chunk: DocumentClient.QueryOutput, encoding: string, callback: (error?: Error, data?: any) => void): void {
    callback(undefined, JSON.stringify(chunk) + '\n')
  }
})

reader
  .pipe(transformOutput)
  .pipe(process.stdout)

const client = new DocumentClient()
const reader = new DocumentClientScanReadable(client, {
  TableName: 'someTable'
});
const transformOutput = new Transform({
  objectMode: true,
  transform (chunk: DocumentClient.ScanOutput, encoding: string, callback: (error?: Error, data?: any) => void): void {
    callback(undefined, JSON.stringify(chunk) + '\n')
  }
})

reader
  .pipe(transformOutput)
  .pipe(process.stdout)