Struct ClickHouseConnection 

pub struct ClickHouseConnection<'a> { /* private fields */ }

A wrapper around ArrowPoolConnection that provides additional functionality relevant for DataFusion.

The methods ClickHouseConnection::tables, ClickHouseConnection::get_schema, and ClickHouseConnection::query_arrow will all be run against the ClickHouse instance.

Implementations

impl<'a> ClickHouseConnection<'a>

pub fn new(conn: ArrowPoolConnection<'a>) -> Self

pub fn new_static(conn: ArrowPoolConnection<'static>) -> Self

pub async fn query_arrow_with_schema( &self, sql: &str, params: &[()], schema: SchemaRef, coerce_schema: bool, ) -> Result<RecordBatchStreamWrapper, DataFusionError>

Issues a query against ClickHouse and returns the result as an arrow SendableRecordBatchStream using the provided schema.

The argument coerce_schema will be passed to RecordBatchStream only if projected_schema is also provided. Otherwise coercion won’t be necessary as the streamed RecordBatches will determine the schema.

Errors

• Returns an error if the query fails.

pub async fn query_arrow( &self, sql: &str, params: &[()], projected_schema: Option<SchemaRef>, ) -> Result<SendableRecordBatchStream, GenericError>

Issues a query against ClickHouse and returns the result as an arrow SendableRecordBatchStream using the provided schema.

This method allows interop with datafusion-table-providers if desired. Otherwise, the method Self::query_arrow_raw can be used to prevent additional wrapping, or Self::query_arrow_with_schema if schema coercion is desired.

Errors

• Returns an error if the query fails.

impl ClickHouseConnection<'_>

pub async fn tables(&self, schema: &str) -> Result<Vec<String>>

Fetch the names of the tables in a schema (database).

Errors

• Returns an error if the tables cannot be fetched.

pub async fn schemas(&self) -> Result<Vec<String>>

Fetch the names of the schemas (databases).

Errors

• Returns an error if the schemas cannot be fetched.

pub async fn get_schema( &self, table_reference: &TableReference, ) -> Result<SchemaRef>

Fetch the schema for a table

Errors

• Returns an error if the schema cannot be fetched.

pub async fn query_arrow_raw( &self, sql: &str, _params: &[()], ) -> Result<ClickHouseResponse<RecordBatch>>

Issues a query against ClickHouse and returns the raw ClickHouseResponse<RecordBatch>

Errors

• Returns an error if the query fails

pub async fn execute( &self, sql: &str, _params: &[()], ) -> Result<u64, GenericError>

Executes a statement against ClickHouse and returns the number of affected rows.

Errors

• Returns an error if the query fails.

Trait Implementations

impl<'a> Debug for ClickHouseConnection<'a>

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

Formats the value using the given formatter.