Struct MemoryTable 

pub struct MemoryTable { /* private fields */ }

A table held in memory as a sequence of chunks.

Implementations

impl MemoryTable

pub fn new(types: Vec<LogicalType>) -> Self

An empty table of the given column types.

pub fn types(&self) -> &[LogicalType]

The column types.

pub fn width(&self) -> usize

How many columns.

pub fn len(&self) -> usize

How many rows, across every chunk.

pub fn is_empty(&self) -> bool

Whether the table has no rows.

pub fn chunk_count(&self) -> usize

How many chunks a scan will read.

pub fn append(&mut self, chunk: Chunk) -> Result<()>

Appends a chunk, which has to have the table’s column types.

An empty chunk is dropped rather than stored, because a scan that has to skip empty chunks is a scan with a branch in it that exists only because an operator upstream was sloppy.

Errors

If the chunk’s columns are not the table’s columns.

pub fn append_rows(&mut self, rows: &[Vec<Value>]) -> Result<()>

Appends rows given one at a time, splitting them into chunks.

The slow way in, for an INSERT and for a test. It transposes, which is the whole cost: rows arrive across the columns and a chunk is down them.

Errors

If a row is not as wide as the table, or if a value is not one its column can hold.

pub fn read(&self, chunk: usize, columns: &[usize]) -> Result<Chunk>

One chunk’s worth of the named columns, in the order they are named.

The columns are copied, because a vector owns its buffer and there is nothing to borrow from yet. Borrowed buffers with a pin are the M2 item in spec/07-execution.md section 7.1, and this is the call that will stop copying when they arrive. Asking for the columns rather than taking them all is what makes that copy proportional to the query instead of to the table, which is the same reason projection pushdown exists.

Errors

If there is no such chunk, or if a column is past the end of the table.

pub fn chunk(&self, index: usize) -> Option<&Chunk>

One stored chunk, whole.

Trait Implementations

impl Clone for MemoryTable

fn clone(&self) -> MemoryTable

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MemoryTable

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

Formats the value using the given formatter.