title: How can I load data from BigQuery to Spanner?
body: <p>I'd like to run a daily job that does some aggregations based on a BigQuery setup. The output is a single table that I write back to BigQuery that is ~80GB over ~900M rows. I'd like to make this dataset available to an online querying usage pattern rather than for analysis.</p>
  
  <p>Querying the data would always be done on specific slices that should be easy to segment by primary or secondary keys. I think Spanner is possibly a good option here in terms of query performance and sharding, but I'm having trouble working out how to load that volume of data into it on a regular basis, and how to handle "switchover" between uploads because it doesn't support table renaming.</p>
  
  <p>Is there a way to perform this sort of bulk loading programatically? We already are using Apache Airflow internally for similar data processing and transfer tasks, so if it's possible to handle it in there that would be even better.</p>