getMutationCount
public long getMutationCount()
The number of mutations that were executed by the transaction. Insert and update operations
count with the multiplicity of the number of columns they affect. For example, inserting a new
record may count as five mutations, if values are inserted into five columns. Delete and delete
range operations count as one mutation regardless of the number of columns affected. Deleting a
row from a parent table that has the ON DELETE CASCADE annotation is also counted as one
mutation regardless of the number of interleaved child rows present. The exception to this is
if there are secondary indexes defined on rows being deleted, then the changes to the secondary
indexes are counted individually. For example, if a table has 2 secondary indexes, deleting a
range of rows in the table counts as 1 mutation for the table, plus 2 mutations for each row
that is deleted because the rows in the secondary index might be scattered over the key-space,
making it impossible for Cloud Spanner to call a single delete range operation on the secondary
indexes. Secondary indexes include the foreign keys backing indexes.