This message is used to select the transaction in which a
Read][google.spanner.v1.Spanner.Read] or
ExecuteSql][google.spanner.v1.Spanner.ExecuteSql] call runs.
See TransactionOptions][google.spanner.v1.TransactionOptions] for more
information about transactions.
Execute the read or SQL query in a temporary transaction. This
is the most efficient way to execute a transaction that
consists of a single SQL query.
Begin a new transaction and execute this read or SQL query in
it. The transaction ID of the new transaction is returned in [
ResultSetMetadata.transaction][google.spanner.v1.ResultSetMeta
data.transaction], which is a
Transaction][google.spanner.v1.Transaction].