Crate rhei_flight 

Arrow Flight SQL gRPC server for the Rhei HTAP engine.

This crate exposes the OLAP backend (DataFusion or DuckDB) over the Arrow Flight SQL protocol, letting clients such as adbc_driver_flightsql (Python), DBeaver, or any standard Arrow Flight SQL driver run analytical queries via gRPC.

Architecture

The crate is built on arrow-flight 58 and tonic 0.14. The core service is RheiFlightSqlService, which implements FlightSqlService and delegates all query execution to rhei_olap::OlapBackend.

Deferred-execution pattern

get_flight_info_* encodes the SQL string into an opaque ticket and returns a FlightInfo immediately — no query planning occurs yet. When the client calls do_get_* with that ticket, the service decodes the SQL, calls rhei_core::OlapEngine::query_stream, and streams Arrow IPC record batches back over the gRPC connection.

Tickets are cheap opaque byte handles; deferring query planning to do_get keeps get_flight_info latency negligible and avoids holding engine resources while the client is not yet ready to consume data.

Compression

Arrow IPC record batches are compressed before transmission. CompressionType::Zstd is the default — it offers the best size/CPU tradeoff for typical columnar workloads. CompressionType::Lz4 is available for CPU-constrained clients that need faster decompression. CompressionType::None disables compression entirely, which is useful on loopback or high-bandwidth LAN links.

Read-only constraint

All write operations (do_put_*) return tonic::Status::unimplemented. Rhei’s OLAP layer carries no DML semantics — INSERT / UPDATE / DELETE go through the OLTP engine (Rusqlite) on a separate path.

Quick start

use std::net::SocketAddr;
use rhei_flight::serve_flight_sql;
let addr: SocketAddr = "0.0.0.0:50051".parse()?;
serve_flight_sql(olap, addr).await?;

Structs

RheiFlightSqlService

Arrow Flight SQL service backed by Rhei’s OLAP engine.

Enums

CompressionType

Compression algorithm applied to Arrow IPC record batches sent over gRPC.

Functions

serve_flight_sql

Start the Arrow Flight SQL gRPC server with CompressionType::Zstd (the default).

serve_flight_sql_with_auth

Start the Arrow Flight SQL gRPC server with bearer-token authentication.

serve_flight_sql_with_compression

Start the Arrow Flight SQL gRPC server with the specified CompressionType.