The Cloud Spanner timestamp at which the transaction committed.
A timestamp in RFC3339 UTC "Zulu" format, with nanosecond resolution and up to nine fractional digits. Examples: "2014-10-02T15:01:23Z" and "2014-10-02T15:01:23.045123456Z".
The total number of mutations for the transaction. Knowing the mutationCount value can help you maximize the number of mutations in a transaction and minimize the number of API round trips. You can also monitor this value to prevent transactions from exceeding the system limit. If the number of mutations exceeds the limit, the server returns INVALID_ARGUMENT.