ALL

All replica nodes must acknowledge the write.

This write consistency level provides the highest consistency, the highest latency, and the lowest availability of any level.

QUORUM

A quorum of replica nodes across all datacenters must acknowledge the write.

Cross-datacenter communication may incur extra latency.

ONE

At least one replica node must acknowledge the write.

Use for high availability and low consistency.

Note: Astra DB does not support write consistency level ONE.

TWO

At least two replica nodes must acknowledge the write.

Similar to ONE.

THREE

At least three replica nodes must acknowledge the write.

Similar to TWO.

ANY

At least one replica node must acknowledge the write, or if no replica nodes are available, a coordinator node must store a hint. If all replica nodes are down at write time, the data will not be available until the replica nodes for that partition have recovered.

This write consistency level provides the lowest latency, the highest write availability, and the lowest consistency.

Note: Astra DB does not support write consistency level ANY.

LOCAL_QUORUM

A quorum of replica nodes in the local datacenter must acknowledge the write. Avoids latency of cross-datacenter communication.

Use LOCAL_QUORUM to maintain consistency within a single datacenter in a multiple-datacenter cluster.

EACH_QUORUM

A quorum of replica nodes in the each datacenter must acknowledge the write.

Use EACH_QUORUM in multi-datacenter clusters to strictly maintain consistency at the same level in each datacenter. Writes will fail if any datacenter fails to achieve a quorum.

LOCAL_ONE

At least one replica node in the local datacenter must acknowledge the write.

Use LOCAL_ONE to a consistency level of ONE without cross-datacenter communication.

Note: Astra DB does not support write consistency level LOCAL_ONE.

SERIAL

Write consistency level SERIAL is a special case for compare and set operations like INSERT, UPDATE, and DELETE operations that use an IF clause.

Use to achieve linearizable consistency for lightweight transactions.

LOCAL_SERIAL

Write consistency level LOCAL_SERIAL is the same as SERIAL, but confined to the local datacenter.

Use to achieve linearizable consistency for lightweight transactions.