Google Cloud Platform for Developers

Write operations

The Cloud Spanner SQL vocabulary does not include traditional DML operations such as INSERT, UPDATE, or DELETE. Instead, such operations must be performed using the Cloud Spanner APIs, usually through one of the many provided Cloud Spanner client libraries. The client specifies a number of mutations to be executed, where each mutation affects a single cell.

Cloud Spanner supports up to 20,000 mutations in a single transaction, and any affected indexes are counted in the total number of mutations. When a client performs a write operation, execution is automatically delegated to the leader. The leader then places a lock on the cells to be mutated, preventing other clients from reading or mutating this data until the transaction ...