string (bytes format)

id may be used to identify the transaction in subsequentsessions.read,ExecuteSql,Commit, orsessions.rollback calls.

Single-use read-only transactions do not have IDs, because single-use transactions do not support multiple requests.

A base64-encoded string.

string (Timestamp format)

For snapshot read-only transactions, the read timestamp chosen for the transaction. Not returned by default: seeTransactionOptions.ReadOnly.return_read_timestamp.

A timestamp in RFC3339 UTC "Zulu" format, accurate to nanoseconds. Example:"2014-10-02T15:01:23.045123456Z".

Uses RFC 3339, where generated output will always be Z-normalized and use 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted. Examples:"2014-10-02T15:01:23Z","2014-10-02T15:01:23.045123456Z" or"2014-10-02T15:01:23+05:30".

object (MultiplexedSessionPrecommitToken)

A precommit token is included in the response of a sessions.beginTransaction request if the read-write transaction is on a multiplexed session and a mutationKey was specified in thesessions.beginTransaction. The precommit token with the highest sequence number from this transaction attempt should be passed to theCommit request for this transaction.