Struct CachedFooter 

pub struct CachedFooter {
    pub schema: Option<usize>,
    pub row_group_rows: Vec<usize>,
    pub row_group_bytes: Vec<usize>,
    pub column_bytes: Vec<usize>,
}

What one file’s footer said, as much of it as a reopen needs.

Everything here comes back out as a FileFooter, so a dataset rebuilt from the cache goes through exactly the same code as one read from the store — the union, the drift groups, the row numbering and the notes are all computed the same way from the same shapes. A cache that took a shortcut past that would be a second implementation of the dataset, and the two would drift.

Fields

schema: Option<usize>

Which of DatasetShape::schemas this file has. None for a file whose footer would not read, which a reopen must remember as unreadable rather than quietly reading it again and getting a different dataset.

row_group_rows: Vec<usize>

The rows in each of its row groups, in order.

row_group_bytes: Vec<usize>

The compressed bytes of each, in the same order. Kept because a note is built from it, and a note that appears on a first open and not on a reopen is a worse bug than a slow open.

column_bytes: Vec<usize>

Uncompressed bytes of each of its schema’s columns, in the schema’s order. A local footer carries them and a binary column’s width is known nowhere else; a cloud footer does not, and leaves this empty.

Trait Implementations

impl Clone for CachedFooter

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CachedFooter

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

Formats the value using the given formatter.

impl Default for CachedFooter

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for CachedFooter

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for CachedFooter

impl PartialEq for CachedFooter

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for CachedFooter

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for CachedFooter