What are the limitations / considerations in scaling down spanner nodes? Since there is a tight coupling of nodes to data stored - is it fair to say that it is highly scalable but not elastic? The following is a quote from the quizlet case study on GCP website...
"it might be impossible to reduce the number of nodes on your database, even if you previously ran the database with that number of nodes."
The word "might" needs some expanding
On
To expand on the "might" -- we restrict the reduction of nodes to meet a 2T/node limit for the instance. You can scale up and down, as long as the down-sizing doesn't cross that threshold.
Hope this helps!
A few things we would recommend to scale down effectively is by deleting unused data (databases, tables, global index, rows etc.). This data will be cleaned within ~7 days, allowing you to potentially run with lower node counts.