Trait AggregateFunction 

pub trait AggregateFunction: Send + Sync {
    // Required methods
    fn name(&self) -> &str;
    fn metadata(&self) -> FunctionMetadata;
    fn argument_specs(&self) -> Vec<ArgSpec>;
    fn on_bind(&self, params: &AggregateBindParams) -> Result<BindResponse>;
    fn initial_state(&self) -> Vec<u8> ;
    fn update(
        &self,
        states: &mut HashMap<i64, Vec<u8>>,
        group_ids: &Int64Array,
        columns: &[ArrayRef],
    ) -> Result<()>;
    fn combine(&self, target: Vec<u8>, source: Vec<u8>) -> Result<Vec<u8>>;
    fn finalize(
        &self,
        output_schema: &SchemaRef,
        group_ids: &Int64Array,
        states: &[Option<Vec<u8>>],
    ) -> Result<RecordBatch>;

    // Provided methods
    fn window(
        &self,
        _partition: &RecordBatch,
        _output_schema: &SchemaRef,
        _frames: &[Vec<(i64, i64)>],
        _filter_mask: Option<&[bool]>,
    ) -> Result<ArrayRef> { ... }
    fn streaming_chunk(
        &self,
        _chunk: &RecordBatch,
        _partition_key_count: usize,
        _order_key_count: usize,
        _states: &mut HashMap<Vec<u8>, Vec<u8>>,
    ) -> Result<ArrayRef> { ... }
    fn finalize_with_args(
        &self,
        output_schema: &SchemaRef,
        group_ids: &Int64Array,
        states: &[Option<Vec<u8>>],
        _args: &Arguments,
    ) -> Result<RecordBatch> { ... }
}

An aggregate VGI function.

Required Methods

fn name(&self) -> &str

fn metadata(&self) -> FunctionMetadata

fn argument_specs(&self) -> Vec<ArgSpec>

fn on_bind(&self, params: &AggregateBindParams) -> Result<BindResponse>

Resolve the (single-column result) output schema.

fn initial_state(&self) -> Vec<u8>

The serialized initial state for a fresh group.

fn update( &self, states: &mut HashMap<i64, Vec<u8>>, group_ids: &Int64Array, columns: &[ArrayRef], ) -> Result<()>

Fold the batch’s rows into the per-group states map. states is pre-loaded (initial state for new groups) for every group id present in group_ids. columns are the input columns with the group-id column already stripped.

fn combine(&self, target: Vec<u8>, source: Vec<u8>) -> Result<Vec<u8>>

Merge source state into target state, returning the new target.

fn finalize( &self, output_schema: &SchemaRef, group_ids: &Int64Array, states: &[Option<Vec<u8>>], ) -> Result<RecordBatch>

Build the single-column output batch: one row per group_ids entry. states[i] is the loaded state for group_ids[i] (None if unseen).

Provided Methods

fn window( &self, _partition: &RecordBatch, _output_schema: &SchemaRef, _frames: &[Vec<(i64, i64)>], _filter_mask: Option<&[bool]>, ) -> Result<ArrayRef>

Evaluate the windowed aggregate for each output row. frames[i] is the list of (begin, end) sub-frames for output row i over the partition’s input columns; returns the output column (one element per row), matching output_schema. Only supports_window functions override this; the default errors.

fn streaming_chunk( &self, _chunk: &RecordBatch, _partition_key_count: usize, _order_key_count: usize, _states: &mut HashMap<Vec<u8>, Vec<u8>>, ) -> Result<ArrayRef>

Process one chunk of a streaming-partitioned session. The chunk’s columns are [partition_key_cols.., order_key_cols.., value_cols..]. states is the cross-chunk per-partition state map (partition-key bytes → opaque state bytes), loaded and persisted by the framework. Returns a same-length output column. Only streaming_partitioned functions override this; the default errors.

fn finalize_with_args( &self, output_schema: &SchemaRef, group_ids: &Int64Array, states: &[Option<Vec<u8>>], _args: &Arguments, ) -> Result<RecordBatch>

Like Self::finalize, but with access to the bind-time arguments (stashed at aggregate_bind, reloaded here). Override for ConstParam(phase= "finalize") aggregates like vgi_percentile. The default ignores them.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors