Trait MergeOperator 

pub trait MergeOperator: Send + Sync {
    // Required method
    fn merge(
        &self,
        key: &Bytes,
        existing_value: Option<Bytes>,
        new_value: Bytes,
    ) -> Bytes;

    // Provided method
    fn merge_batch(
        &self,
        key: &Bytes,
        existing_value: Option<Bytes>,
        operands: &[Bytes],
    ) -> Bytes { ... }
}

Trait for merging existing values with new values.

Merge operators must be associative: merge(merge(a, b), c) == merge(a, merge(b, c)). This ensures consistent merging behavior regardless of the order of operations.

Required Methods

fn merge( &self, key: &Bytes, existing_value: Option<Bytes>, new_value: Bytes, ) -> Bytes

Merges an existing value with a new value to produce a merged result.

Arguments

• key - The key associated with the values being merged
• existing_value - The current value stored in the database (if any)
• new_value - The new value to merge with the existing value

Returns

The merged value.

Provided Methods

fn merge_batch( &self, key: &Bytes, existing_value: Option<Bytes>, operands: &[Bytes], ) -> Bytes

Merges a batch of operands with an optional existing value.

The default implementation applies pairwise merging. Implementations can override this for better performance by constructing a single merge result once for multiple input values.

Arguments

• key - The key associated with the values being merged
• existing_value - The current value stored in the database (if any)
• operands - A slice of operands to merge, ordered from oldest to newest

Implementors