Enum ConsistencyMode 

pub enum ConsistencyMode {
    Default,
    Consistent,
    Stale,
}

Most of the read query endpoints support multiple levels of consistency. Since no policy will suit all clients’ needs, these consistency modes allow the user to have the ultimate say in how to balance the trade-offs inherent in a distributed system.

Variants

Default

If not specified, the default is strongly consistent in almost all cases. However, there is a small window in which a new leader may be elected during which the old leader may service stale values. The trade-off is fast reads but potentially stale values. The condition resulting in stale reads is hard to trigger, and most clients should not need to worry about this case. Also, note that this race condition only applies to reads, not writes.

Consistent

This mode is strongly consistent without caveats. It requires that a leader verify with a quorum of peers that it is still leader. This introduces an additional round-trip to all server nodes. The trade-off is increased latency due to an extra round trip. Most clients should not use this unless they cannot tolerate a stale read.

Stale

This mode allows any server to service the read regardless of whether it is the leader. This means reads can be arbitrarily stale; however, results are generally consistent to within 50 milliseconds of the leader. The trade-off is very fast and scalable reads with a higher likelihood of stale values. Since this mode allows reads without a leader, a cluster that is unavailable will still be able to respond to queries.

Trait Implementations

impl Clone for ConsistencyMode

fn clone(&self) -> ConsistencyMode

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ConsistencyMode

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ConsistencyMode

fn default() -> Self

Return ConsistencyMode::Default

impl<'de> Deserialize<'de> for ConsistencyMode

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for ConsistencyMode

fn eq(&self, other: &ConsistencyMode) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for ConsistencyMode

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ConsistencyMode