Struct StringColumn 

pub struct StringColumn { /* private fields */ }

A column of strings: the views, and the blocks the long ones live in.

Blocks are append only and never move, so an offset recorded in a view stays correct for the life of the column. Pushing a string longer than a block gives it a block of its own rather than splitting it, which keeps every string contiguous and keeps Self::get free of a stitching path that would be wrong more often than it ran.

Implementations

impl StringColumn

pub fn new() -> Self

An empty column.

pub fn with_capacity(capacity: usize) -> Self

An empty column with room for capacity strings.

pub fn len(&self) -> usize

How many strings are in the column.

pub fn is_empty(&self) -> bool

Whether the column has no strings in it.

pub fn views(&self) -> &[StringView]

The views, for a kernel that wants to compare prefixes without reading any payload.

pub fn push(&mut self, text: &str) -> usize

Appends a string and returns its index.

pub fn bytes(&self, index: usize) -> Option<&[u8]>

The bytes at index, or None past the end.

This is what a comparison, a hash and an equality check all actually want, and it is worth having separately from Self::get because that one validates UTF-8 and they do not need it. Everything in a column arrived through Self::push, which takes a &str, so the bytes are valid either way and the validation is a scan of the payload that changes no answer. On a varchar filter it was measured at most of the per row cost.

pub fn get(&self, index: usize) -> Option<&str>

The string at index, or None past the end.

pub fn iter(&self) -> impl Iterator<Item = &str>

Every string in order.

pub fn heap_bytes(&self) -> usize

Total bytes of payload held in blocks, which is what the memory accounting wants.

Trait Implementations

impl Clone for StringColumn

fn clone(&self) -> StringColumn

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StringColumn

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

Formats the value using the given formatter.

impl Default for StringColumn

fn default() -> StringColumn

Returns the “default value” for a type.

impl Eq for StringColumn

impl<'a> Extend<&'a str> for StringColumn

fn extend<T: IntoIterator<Item = &'a str>>(&mut self, iter: T)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: T)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<'a> FromIterator<&'a str> for StringColumn

fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self

Creates a value from an iterator.

impl PartialEq for StringColumn

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for StringColumn