Struct SchemaRegistry 

pub struct SchemaRegistry { /* private fields */ }

The schema registry takes care of storing and retrieving table schemas from memory.

Implementations

impl SchemaRegistry

pub fn load(mm: &mut impl MemoryAccess) -> MemoryResult<Self>

Load the schema registry from memory.

pub const fn schema_hash(&self) -> u64

Returns the cached hash of every persisted schema snapshot.

pub fn register_table<TS>( &mut self, mm: &mut impl MemoryAccess, ) -> MemoryResult<TableRegistryPage>

where TS: TableSchema,

Registers a table and allocates it registry page.

The TableSchema type parameter is used to get the TableSchema::fingerprint of the table schema. The fingerprint is derived from the table name, so two distinct names that hash to the same value are detected eagerly: when the slot is already occupied by a table with a different name, MemoryError::NameCollision is returned and no allocation is performed.

Errors

• MemoryError::NameCollision when the fingerprint slot is occupied by a table whose persisted snapshot carries a different name.
• Any MemoryError propagated from page allocation, snapshot init, or the registry write-back.

pub fn save(&self, mm: &mut impl MemoryAccess) -> MemoryResult<()>

Save the schema registry to memory.

pub fn table_registry_page<TS>(&self) -> Option<TableRegistryPage>

where TS: TableSchema,

Returns the table registry page for a given table schema.

pub fn table_registry_page_by_name( &self, name: &str, ) -> Option<TableRegistryPage>

Returns the table registry page for the table with the given name.

Used by the migration engine, which knows tables only by name when applying ops decoded from snapshots.

pub fn register_table_from_snapshot( &mut self, snapshot: &TableSchemaSnapshot, mm: &mut impl MemoryAccess, ) -> MemoryResult<TableRegistryPage>

Registers a table from a snapshot, allocating its registry pages.

The migration engine uses this entry point when applying a MigrationOp::CreateTable: the source of truth is a TableSchemaSnapshot, not a TableSchema type.

Errors

• MemoryError::NameCollision when the fingerprint slot is occupied by a table with a different name.
• Any MemoryError propagated from page allocation, snapshot init, index init, or registry persistence.

pub fn unregister_table( &mut self, name: &str, mm: &mut impl MemoryAccess, ) -> MemoryResult<Option<TableRegistryPage>>

Removes the table identified by name from the registry, releases every page it owned back to the unclaimed-pages ledger, and persists the updated registry.

Used by the migration engine when applying a MigrationOp::DropTable.

Returns the TableRegistryPage previously associated with the table, or None if no such table was registered.

Errors

Returns a MemoryError if loading the table registry, releasing its pages, or persisting the updated schema registry fails.

pub fn stored_snapshots( &self, mm: &mut impl MemoryAccess, ) -> MemoryResult<Vec<TableSchemaSnapshot>>

Returns the persisted TableSchemaSnapshot for every registered table.

The order is unspecified. Callers that need a stable order (e.g. for drift hashing) must sort by TableSchemaSnapshot::name.

Errors

Returns the first MemoryError encountered while loading any snapshot page.

pub fn refresh_schema_hash( &mut self, mm: &mut impl MemoryAccess, ) -> MemoryResult<()>

Recomputes the cached schema hash from the currently registered tables.

Trait Implementations

impl Clone for SchemaRegistry

fn clone(&self) -> SchemaRegistry

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SchemaRegistry

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

Formats the value using the given formatter.

impl Default for SchemaRegistry

fn default() -> SchemaRegistry

Returns the “default value” for a type.

impl Encode for SchemaRegistry

const SIZE: DataSize = DataSize::Dynamic

The size characteristic of the data type.

const ALIGNMENT: PageOffset = DEFAULT_ALIGNMENT

The alignment requirement in bytes for the 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.

fn size(&self) -> MSize

Returns the size in bytes of the encoded data type.

impl PartialEq for SchemaRegistry

fn eq(&self, other: &SchemaRegistry) -> 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 Eq for SchemaRegistry

impl StructuralPartialEq for SchemaRegistry