Trait mz_transform::StatisticsOracle

source · 
pub trait StatisticsOracle: Debug + Send {
    // Required method
    fn cardinality_estimate(&self, id: GlobalId) -> Option<usize>;
}
Expand description

A trait for a type that can estimate statistics about a given GlobalId

Required Methods§

source

fn cardinality_estimate(&self, id: GlobalId) -> Option<usize>

Returns a cardinality estimate for the given identifier

Returning None means “no estimate”; returning Some(0) means estimating that the shard backing id is empty

Implementors§