Struct VirtualNode

#[repr(transparent)]
pub struct VirtualNode(u16);

VirtualNode (a.k.a. Vnode) is a minimal partition that a set of keys belong to. It is used for consistent hashing.

Tuple Fields

0: u16

Implementations

impl VirtualNode

pub const COUNT_FOR_COMPAT: usize = 256usize

The total count of virtual nodes, for compatibility purposes ONLY.

Typical use cases:

• As the default value for the session configuration.
• As the vnode count for all streaming jobs, fragments, and tables that were created before the variable vnode count support was introduced.
• As the vnode count for singletons.

impl VirtualNode

pub const COUNT_FOR_TEST: usize = 256usize

The total count of virtual nodes, for testing purposes.

pub const MAX_FOR_TEST: VirtualNode

The maximum value of the virtual node, for testing purposes.

impl VirtualNode

pub const MAX_COUNT: usize = 32_768usize

The maximum count of virtual nodes that fits in VirtualNodeInner.

Note that the most significant bit is not used. This is because we use signed integers (i16) for the scalar representation, where overflow can be confusing in terms of ordering.

pub const MAX_REPRESENTABLE: VirtualNode

The maximum value of the virtual node that can be represented.

Note that this is NOT the maximum value of the virtual node, which depends on the configuration.

pub const SIZE: usize = 2usize

The size of a virtual node in bytes, in memory or serialized representation.

impl VirtualNode

pub const RW_TYPE: DataType = DataType::Int16

We may use VirtualNode as a datum in a stream, or store it as a column. Hence this reifies it as a RW datatype.

pub const ZERO: VirtualNode

The minimum (zero) value of the virtual node.

pub const fn from_index(index: usize) -> Self

Creates a virtual node from the usize index.

pub const fn to_index(self) -> usize

Returns the usize the virtual node used for indexing.

pub const fn from_scalar(scalar: i16) -> Self

Creates a virtual node from the given scalar representation. Used by VNODE expression.

pub fn from_datum_ref(datum: DatumRef<'_>) -> Self

pub const fn to_scalar(self) -> i16

Returns the scalar representation of the virtual node. Used by VNODE expression.

pub const fn to_datum(self) -> Datum

pub const fn from_be_bytes(bytes: [u8; 2]) -> Self

Creates a virtual node from the given big-endian bytes representation.

pub const fn to_be_bytes(self) -> [u8; 2]

Returns the big-endian bytes representation of the virtual node.

pub fn all(vnode_count: usize) -> AllVirtualNodeIter

Iterates over all virtual nodes.

impl VirtualNode

pub fn compute_chunk( data_chunk: &DataChunk, keys: &[usize], vnode_count: usize, ) -> Vec<VirtualNode>

pub fn compute_chunk_for_test( data_chunk: &DataChunk, keys: &[usize], ) -> Vec<VirtualNode>

Equivalent to Self::compute_chunk with VirtualNode::COUNT_FOR_TEST as the vnode count.

pub fn compute_row( row: impl Row, indices: &[usize], vnode_count: usize, ) -> VirtualNode

pub fn compute_row_for_test(row: impl Row, indices: &[usize]) -> VirtualNode

Equivalent to Self::compute_row with VirtualNode::COUNT_FOR_TEST as the vnode count.

Trait Implementations

impl Clone for VirtualNode

fn clone(&self) -> VirtualNode

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for VirtualNode

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

Formats the value using the given formatter.

impl Display for VirtualNode

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

Formats the value using the given formatter.

impl Hash for VirtualNode

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<T: VnodeMappingItem> Index<VirtualNode> for VnodeMapping<T>

type Output = <T as VnodeMappingItem>::Item

The returned type after indexing.

fn index(&self, vnode: VirtualNode) -> &Self::Output

Performs the indexing (container[index]) operation.

impl Ord for VirtualNode

fn cmp(&self, other: &VirtualNode) -> 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 VirtualNode

fn eq(&self, other: &VirtualNode) -> 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 VirtualNode

fn partial_cmp(&self, other: &VirtualNode) -> 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 Copy for VirtualNode

impl Eq for VirtualNode

impl !From<HashCode<Crc32FastBuilder>> for VirtualNode

vnode_count must be provided to convert a hash code to a virtual node.

Use Crc32HashCodeToVnodeExt::to_vnode instead.

impl StructuralPartialEq for VirtualNode