Cloud spanner's mutation limit per commit 20,000. For a mutation delete using KeySet, does this count as one mutation, or does the size of the KeySet determine the number of mutations? For example:
List<Mutation> mutations = new ArrayList<>();
mutations.add(
Mutation.delete(
"Albums", KeySet.newBuilder().addKey(Key.of(2, 1)).addKey(Key.of(2, 3)).build()));
dbClient.write(mutations);
Does this count as one mutation, or two? If I'm doing a batch delete with KeySet, then do I need to page the keys into sets of 20K?
The size of the KeySet determines the number of mutations, with each key counting as a mutation.
Note that any indexes on the table will also multiply the mutation count for each key: https://cloud.google.com/spanner/quotas#note2.