Struct Catalog 

pub struct Catalog { /* private fields */ }

Wrapper catalog supporting generation of pg metadata (e.g. pg_catalog schema).

Implementations

impl Catalog

pub fn new(wrapped: Arc<dyn CatalogProvider>) -> Self

Create a new wrapper catalog that provides postgres metadata for the contained objects.

Examples found in repository

examples/datafusion.rs (line 25)

async fn new_engine() -> DataFusionEngine {
	let ctx = SessionContext::new_with_config(
		SessionConfig::new()
			.with_information_schema(true)
			.with_create_default_catalog_and_schema(false),
	);

	let mem_catalog = Arc::new(MemoryCatalogProvider::new());
	mem_catalog
		.register_schema("public", Arc::new(MemorySchemaProvider::new()))
		.expect("failed to register schema");

	ctx.register_catalog("datafusion", Arc::new(Catalog::new(mem_catalog)));

	ctx.register_csv(
		"test_100_4buckets",
		"convergence-arrow/data/100_4buckets.csv",
		CsvReadOptions::new(),
	)
	.await
	.expect("failed to register csv");

	ctx.register_udf(create_udf(
		"pg_backend_pid",
		vec![],
		DataType::Int32,
		Volatility::Stable,
		Arc::new(|_| Ok(ColumnarValue::Scalar(ScalarValue::Int32(Some(0))))),
	));

	ctx.register_udf(create_udf(
		"current_schema",
		vec![],
		DataType::Utf8,
		Volatility::Stable,
		Arc::new(|_| Ok(ColumnarValue::Scalar(ScalarValue::Utf8(Some("public".to_owned()))))),
	));

	DataFusionEngine::new(ctx)
}

Trait Implementations

impl CatalogProvider for Catalog

fn as_any(&self) -> &dyn Any

Returns the catalog provider as Any so that it can be downcast to a specific implementation.

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

Retrieves the list of available schema names in this catalog.

fn schema(&self, name: &str) -> Option<Arc<dyn SchemaProvider>>

Retrieves a specific schema from the catalog by name, provided it exists.

fn register_schema( &self, name: &str, schema: Arc<dyn SchemaProvider>, ) -> Result<Option<Arc<dyn SchemaProvider>>, DataFusionError>

Adds a new schema to this catalog.

fn deregister_schema( &self, _name: &str, _cascade: bool, ) -> Result<Option<Arc<dyn SchemaProvider>>, DataFusionError>

Removes a schema from this catalog. Implementations of this method should return errors if the schema exists but cannot be dropped. For example, in DataFusion’s default in-memory catalog, MemoryCatalogProvider, a non-empty schema will only be successfully dropped when cascade is true. This is equivalent to how DROP SCHEMA works in PostgreSQL.

impl Debug for Catalog

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

Formats the value using the given formatter.