Struct TableSchemaSnapshot 

pub struct TableSchemaSnapshot {
    pub version: u8,
    pub name: String,
    pub primary_key: String,
    pub alignment: u32,
    pub columns: Vec<ColumnSnapshot>,
    pub indexes: Vec<IndexSnapshot>,
}

Frozen, comparable view of a TableSchema used for migration detection.

A snapshot captures the structural shape of a table at a point in time so that two versions can be diffed to derive the migration steps required to bring the on-disk representation up to date with the current schema definition.

Fields

version: u8

Version tag of the snapshot binary layout, see SCHEMA_SNAPSHOT_VERSION.

name: String

Name of the table this snapshot was taken from.

primary_key: String

Name of the column declared as primary key.

alignment: u32

Record alignment, in bytes, used for on-disk layout.

columns: Vec<ColumnSnapshot>

Snapshots of every column in declaration order.

indexes: Vec<IndexSnapshot>

Snapshots of every secondary index defined on the table.

Implementations

impl TableSchemaSnapshot

pub fn latest_version() -> u8

Returns the latest version of the snapshot format.

pub fn validate_encoding(&self) -> MemoryResult<()>

Checks that every name, count and nested payload fits its on-disk field, so the snapshot round-trips exactly through Encode.

Table, primary key, column, foreign key, custom type and index column names, and the number of columns of each index, are limited to 255 bytes or entries. Column and index counts, each encoded column, index and default value, and the whole snapshot are limited to 65 535 bytes or entries.

Must be called before the snapshot is persisted: Encode::encode cannot report an error and its output is unspecified for a snapshot that fails this check.

Errors

Returns MemoryError::ConstraintViolation naming the first field that exceeds its limit.

Trait Implementations

impl Clone for TableSchemaSnapshot

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 TableSchemaSnapshot

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for TableSchemaSnapshot

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Encode for TableSchemaSnapshot

const ALIGNMENT: PageOffset = 32

The alignment requirement in bytes for the data type.

const SIZE: DataSize = DataSize::Dynamic

The size characteristic of the data type.

fn size(&self) -> MSize

Returns the size in bytes of the encoded data type.

fn encode(&self) -> Cow<'_, [u8]>

Encodes the data type into a vector of bytes.

fn decode(data: Cow<'_, [u8]>) -> MemoryResult<Self>

where Self: Sized,

Decodes the data type from a slice of bytes.

impl Eq for TableSchemaSnapshot

impl PartialEq for TableSchemaSnapshot

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for TableSchemaSnapshot

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 TableSchemaSnapshot