Client-side timestamps | ScyllaDB Docs

Client-side timestamps¶

ScyllaDB/Cassandra uses timestamps to serialize write operations. That is, values with a more current timestamp are considered to be the most up-to-date version of that information. By default, timestamps are assigned by the driver on the client-side using a monotonically increasing timestamp generator. This behavior can be overridden by configuring the driver to use a server-side timestamps or assigning a timestamp directly to a CassStatement or CassBatch.

Monotonically Increasing Timestamp Generator¶

The monotonic timestamp generator guarantees that all writes that share this generator will be given monotonically increasing timestamps. This generator produces microsecond timestamps with the sub-millisecond part generated using an atomic counter. That guarantees that no more than 1000 timestamps will be generated for a given millisecond clock tick even when shared by multiple sessions.

Warning: If the rate of 1000 timestamps per millisecond is exceeded, this generator will produce duplicate timestamps.

CassCluster* cluster = cass_cluster_new();

CassTimestampGen* timestamp_gen = cass_timestamp_gen_monotonic_new();

cass_cluster_set_timestamp_gen(cluster, timestamp_gen);

/* ... */

/* Connect sessions */

/* Timestamp generators must be freed */
cass_timestamp_gen_free(timestamp_gen);

cass_cluster_free(cluster);

All sessions that connect using this cluster object will share this same timestamp generator.

Per Statement/Batch timestamps¶

Timestamps can also be assigned to individuals CassStatement or CassBatch requests.

CassStatement* statement = cass_statement_new("INSERT INTO * ...", 2);

/* Add a timestamp to the statement */
cass_statement_set_timestamp(statement, 123456789);

CassBatch* batch = cass_batch_new(CASS_BATCH_TYPE_LOGGED);

/* Add a timestamp to the batch */
cass_batch_set_timestamp(batch, 123456789);

/* Add statements to batch */

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