Package overview

The public surface spans three crates. Everything below is generated from the source, so a symbol’s page is the authority for its exact shape.

Crate	What it is
vgi	The worker framework: the function traits, Worker, catalogs, storage, transports.
vgi-protocol	The wire types, re-exported by vgi at their original paths — cache_control, ipc, wire.
vgi-client	The client: attach, discovery, and calling functions without DuckDB in the middle.

The five traits

Copy Copied!

use vgi::function::ScalarFunction;              // 1 row  → 1 value
use vgi::table_function::TableFunction;        // args   → N rows  (+ TableProducer)
use vgi::table_in_out::TableInOutFunction;     // N rows → M rows, streaming
use vgi::aggregate::AggregateFunction;         // N rows → 1 value per group
use vgi::buffering::TableBufferingFunction;    // N rows → M rows, after all input

Each is registered on a Worker with the matching register_* call. copy_from and copy_to add two more for custom COPY formats.

`Result` and `RpcError` come from the RPC layer

Every trait method returns vgi_rpc::Result. From the release after 0.29.0 the vgi crate re-exports both, so use vgi::{Result, RpcError}; is the right version by construction. On 0.29.0 you need a direct vgi-rpc = "0.21" dependency — see the tutorial for why the version matters.

Reference

Scalar functions ScalarFunction, ArgSpec, the bind and process params.

Table functions TableFunction and the producer that streams its rows.

Table-in-out functions Streaming a relation through.

Buffering functions Sink, combine, source.

Aggregate functions Per-group accumulation over Vec state.

COPY formats Your own format through COPY … FROM / TO.

Worker & serving Worker, the four transports, the wasm entry points.

Catalogs CatalogModel, schemas, tables, views, macros.

Arguments Declaring a signature, reading the values.

Cache control Advertising a result as reusable.

Pushdown & statistics Predicates pushed toward the scan, and what you report back.

State storage State across calls and across processes.

Secrets & settings Credentials and session settings.

Protocol & Arrow Wire shapes, IPC helpers, numeric utilities.

Client Calling a worker from Rust.