Struct VariantDecimal4 

pub struct VariantDecimal4 {
    integer: i32,
    scale: u8,
}

Represents a 4-byte decimal value in the Variant format.

This struct stores a decimal number using a 32-bit signed integer for the coefficient and an 8-bit unsigned integer for the scale (number of decimal places). Its precision is limited to 9 digits.

For valid precision and scale values, see the Variant specification: https://github.com/apache/parquet-format/blob/87f2c8bf77eefb4c43d0ebaeea1778bd28ac3609/VariantEncoding.md?plain=1#L418-L420

Example: Create a VariantDecimal4

// Create a value representing the decimal 123.4567
let decimal = VariantDecimal4::try_new(1234567, 4).expect("Failed to create decimal");

Fields

integer: i32

scale: u8

Implementations

impl VariantDecimal4

pub const MAX_PRECISION: u8 = arrow_schema::DECIMAL32_MAX_PRECISION

Maximum number of significant digits (9 for 4-byte decimals)

impl VariantDecimal4

pub fn try_new(integer: i32, scale: u8) -> Result<Self, ArrowError>

Attempts to create a new instance of this decimal type, failing if the value is too wide or the scale is too large.

pub fn integer(&self) -> i32

Returns the unscaled integer value of the decimal.

For example, if the decimal is 123.45, this will return 12345.

pub fn scale(&self) -> u8

Returns the scale of the decimal (how many digits after the decimal point).

For example, if the decimal is 123.45, this will return 2.

pub fn as_integer(&self) -> Option<i32>

Returns Some(i32) if scale is zero or integer of the decimal is divisible by 10^scale, None for other values.

Examples

use parquet_variant::VariantDecimal4;
//Return the integer if scale is 0
let d1 = VariantDecimal4::try_new(123, 0).unwrap();
assert_eq!(d1.as_integer(), Some(123));
// or if the integer is divisible by 10^scale
let d2 = VariantDecimal4::try_new(100, 2).unwrap();
assert_eq!(d2.as_integer(), Some(1));
// or the integer is negative and divisible by 10^scale
let d3 = VariantDecimal4::try_new(-100, 2).unwrap();
assert_eq!(d3.as_integer(), Some(-1));
// or if the integer is 0
let d4 = VariantDecimal4::try_new(0, 4).unwrap();
assert_eq!(d4.as_integer(), Some(0));
// but not if the integer is not divisible by 10^scale
let d5 = VariantDecimal4::try_new(123, 2).unwrap();
assert_eq!(d5.as_integer(), None);
// or the integer is negative and not divisible by 10^scale
let d6 = VariantDecimal4::try_new(-123, 2).unwrap();
assert_eq!(d6.as_integer(), None);

Trait Implementations

impl Clone for VariantDecimal4

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for VariantDecimal4

impl Debug for VariantDecimal4

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

Formats the value using the given formatter.

impl Display for VariantDecimal4

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

Formats the value using the given formatter.

impl From<VariantDecimal4> for VariantDecimal8

fn from(decimal: VariantDecimal4) -> Self

Converts to this type from the input type.

impl From<VariantDecimal4> for VariantDecimal16

fn from(decimal: VariantDecimal4) -> Self

Converts to this type from the input type.

impl From<VariantDecimal4> for Variant<'_, '_>

fn from(value: VariantDecimal4) -> Self

Converts to this type from the input type.

impl PartialEq for VariantDecimal4

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for VariantDecimal4

impl TryFrom<VariantDecimal8> for VariantDecimal4

type Error = ArrowError

The type returned in the event of a conversion error.

fn try_from(decimal: VariantDecimal8) -> Result<Self, ArrowError>

Performs the conversion.

impl TryFrom<VariantDecimal16> for VariantDecimal4

type Error = ArrowError

The type returned in the event of a conversion error.

fn try_from(decimal: VariantDecimal16) -> Result<Self, ArrowError>

Performs the conversion.

impl TryFrom<i32> for VariantDecimal4

type Error = ArrowError

The type returned in the event of a conversion error.

fn try_from(integer: i32) -> Result<Self, ArrowError>

Performs the conversion.

impl VariantDecimalType for VariantDecimal4

const MAX_PRECISION: u8 = Self::MAX_PRECISION

Maximum number of significant digits this decimal type can represent (9, 18, or 38)

const MAX_UNSCALED_VALUE: i32

The largest positive unscaled value that fits in Self::MAX_PRECISION digits.

type Native = i32

The underlying signed integer type (i32, i64, or i128)

fn try_new(integer: i32, scale: u8) -> Result<Self, ArrowError>

Creates a new decimal value from the given unscaled integer and scale, failing if the integer’s width, or the requested scale, exceeds MAX_PRECISION.

fn try_new_with_signed_scale( integer: i32, scale: i8, ) -> Result<Self, ArrowError>

Attempts to convert an unscaled arrow decimal value to the indicated variant decimal type.

fn integer(&self) -> i32

Returns the unscaled integer value

fn scale(&self) -> u8

Returns the scale (number of digits after the decimal point)

fn as_integer(&self) -> Option<i32>

Converts the decimal as an integer if possible,

fn is_valid_precision_and_scale(precision: &u8, scale: &i8) -> bool

True if the given precision and scale are valid for this variant decimal type.