Trait SchemaProvider 

pub trait SchemaProvider:
    Any
    + Debug
    + Sync
    + Send {
    // Required methods
    fn table_names(&self) -> Vec<String>;
    fn table<'life0, 'life1, 'async_trait>(
        &'life0 self,
        name: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = Result<Option<Arc<dyn TableProvider>>, DataFusionError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn table_exist(&self, name: &str) -> bool;

    // Provided methods
    fn owner_name(&self) -> Option<&str> { ... }
    fn table_type<'life0, 'life1, 'async_trait>(
        &'life0 self,
        name: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = Result<Option<TableType>>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
    fn register_table(
        &self,
        name: String,
        table: Arc<dyn TableProvider>,
    ) -> Result<Option<Arc<dyn TableProvider>>> { ... }
    fn deregister_table(
        &self,
        name: &str,
    ) -> Result<Option<Arc<dyn TableProvider>>> { ... }
}

Represents a schema, comprising a number of named tables.

Please see CatalogProvider for details of implementing a custom catalog.

Required Methods

fn table_names(&self) -> Vec<String>

Retrieves the list of available table names in this schema.

fn table<'life0, 'life1, 'async_trait>( &'life0 self, name: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<Option<Arc<dyn TableProvider>>, DataFusionError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Retrieves a specific table from the schema by name, if it exists, otherwise returns None.

fn table_exist(&self, name: &str) -> bool

Returns true if table exist in the schema provider, false otherwise.

Provided Methods

fn owner_name(&self) -> Option<&str>

Returns the owner of the Schema, default is None. This value is reported as part of `information_tables.schemata

fn table_type<'life0, 'life1, 'async_trait>( &'life0 self, name: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<Option<TableType>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Retrieves the type of a specific table from the schema by name, if it exists, otherwise returns None. Implementations for which this operation is cheap but Self::table is expensive can override this to improve operations that only need the type, e.g. SELECT * FROM information_schema.tables.

fn register_table( &self, name: String, table: Arc<dyn TableProvider>, ) -> Result<Option<Arc<dyn TableProvider>>>

If supported by the implementation, adds a new table named name to this schema.

If a table of the same name was already registered, returns “Table already exists” error.

fn deregister_table(&self, name: &str) -> Result<Option<Arc<dyn TableProvider>>>

If supported by the implementation, removes the name table from this schema and returns the previously registered TableProvider, if any.

If no name table exists, returns Ok(None).

Implementations

impl dyn SchemaProvider

pub fn is<T: SchemaProvider>(&self) -> bool

Returns true if the schema provider is of type T.

Prefer this over downcast_ref::<T>().is_some(). Works correctly when called on Arc<dyn SchemaProvider> via auto-deref.

pub fn downcast_ref<T: SchemaProvider>(&self) -> Option<&T>

Attempts to downcast this schema provider to a concrete type T, returning None if the provider is not of that type.

Works correctly when called on Arc<dyn SchemaProvider> via auto-deref, unlike (&arc as &dyn Any).downcast_ref::<T>() which would attempt to downcast the Arc itself.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl SchemaProvider for DynamicFileSchemaProvider

impl SchemaProvider for InformationSchemaProvider

impl SchemaProvider for ListingSchemaProvider

impl SchemaProvider for MemorySchemaProvider