Struct ColumnStatistics 

pub struct ColumnStatistics {
    pub codec: ColumnCodec,
    pub count: u64,
    pub min: Option<f64>,
    pub max: Option<f64>,
    pub sum: Option<f64>,
    pub cardinality: Option<u32>,
    pub compressed_bytes: u64,
    pub uncompressed_bytes: u64,
}

Per-column statistics computed at flush time.

Stored in partition metadata for predicate pushdown and approximate query answers without decompression.

Fields

codec: ColumnCodec

Codec used for this column in this partition.

count: u64

Number of non-null values.

min: Option<f64>

Minimum value (as f64 for numeric columns, 0.0 for non-numeric).

max: Option<f64>

Maximum value.

sum: Option<f64>

Sum of values (for numeric columns).

cardinality: Option<u32>

Number of distinct values (for symbol/tag columns).

compressed_bytes: u64

Compressed size in bytes for this column.

uncompressed_bytes: u64

Uncompressed size in bytes.

Implementations

impl ColumnStatistics

pub fn new(codec: ColumnCodec) -> Self

Create empty statistics with just the codec.

pub fn from_i64( values: &[i64], codec: ColumnCodec, compressed_bytes: u64, ) -> Self

Compute statistics for an i64 column.

pub fn from_f64( values: &[f64], codec: ColumnCodec, compressed_bytes: u64, ) -> Self

Compute statistics for an f64 column.

pub fn from_symbols( values: &[u32], cardinality: u32, codec: ColumnCodec, compressed_bytes: u64, ) -> Self

Compute statistics for a symbol column.

pub fn compression_ratio(&self) -> f64

Compression ratio (uncompressed / compressed). Returns 1.0 if no data.

Trait Implementations

impl Clone for ColumnStatistics

fn clone(&self) -> ColumnStatistics

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ColumnStatistics

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ColumnStatistics

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ColumnStatistics

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

where __S: Serializer,

Serialize this value into the given Serde serializer.