Struct SizeStatistics

pub struct SizeStatistics {
    pub unencoded_byte_array_data_bytes: Option<i64>,
    pub repetition_level_histogram: Option<Vec<i64>>,
    pub definition_level_histogram: Option<Vec<i64>>,
}

A structure for capturing metadata for estimating the unencoded, uncompressed size of data written. This is useful for readers to estimate how much memory is needed to reconstruct data in their memory model and for fine grained filter pushdown on nested structures (the histograms contained in this structure can help determine the number of nulls at a particular nesting level and maximum length of lists).

Fields

unencoded_byte_array_data_bytes: Option<i64>

The number of physical bytes stored for BYTE_ARRAY data values assuming no encoding. This is exclusive of the bytes needed to store the length of each byte array. In other words, this field is equivalent to the (size of PLAIN-ENCODING the byte array values) - (4 bytes * number of values written). To determine unencoded sizes of other types readers can use schema information multiplied by the number of non-null and null values. The number of null/non-null values can be inferred from the histograms below.

For example, if a column chunk is dictionary-encoded with dictionary [“a”, “bc”, “cde”], and a data page contains the indices [0, 0, 1, 2], then this value for that data page should be 7 (1 + 1 + 2 + 3).

This field should only be set for types that use BYTE_ARRAY as their physical type.

repetition_level_histogram: Option<Vec<i64>>

When present, there is expected to be one element corresponding to each repetition (i.e. size=max repetition_level+1) where each element represents the number of times the repetition level was observed in the data.

This field may be omitted if max_repetition_level is 0 without loss of information.

definition_level_histogram: Option<Vec<i64>>

Same as repetition_level_histogram except for definition levels.

This field may be omitted if max_definition_level is 0 or 1 without loss of information.

Implementations

impl SizeStatistics

pub fn new<F1, F2, F3>( unencoded_byte_array_data_bytes: F1, repetition_level_histogram: F2, definition_level_histogram: F3, ) -> SizeStatistics

where F1: Into<Option<i64>>, F2: Into<Option<Vec<i64>>>, F3: Into<Option<Vec<i64>>>,

Trait Implementations

impl Clone for SizeStatistics

fn clone(&self) -> SizeStatistics

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for SizeStatistics

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

Formats the value using the given formatter.

impl Default for SizeStatistics

fn default() -> SizeStatistics

Returns the “default value” for a type.

impl Hash for SizeStatistics

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for SizeStatistics

fn cmp(&self, other: &SizeStatistics) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for SizeStatistics

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for SizeStatistics

fn partial_cmp(&self, other: &SizeStatistics) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl TSerializable for SizeStatistics

fn read_from_in_protocol<T: TInputProtocol>( i_prot: &mut T, ) -> Result<SizeStatistics>

Reads the struct from the input Thrift protocol

fn write_to_out_protocol<T: TOutputProtocol>( &self, o_prot: &mut T, ) -> Result<()>

Writes the struct to the output Thrift protocol

impl Eq for SizeStatistics

impl StructuralPartialEq for SizeStatistics