sqlx-exasol

A database driver for Exasol to be used with the Rust sqlx framework, based on the Exasol Websocket API. Inspired by Py-Exasol and based on the (now archived) rust-exasol sync driver.

Based on sqlx version 0.9.0-alpha.1.

Comparison to native sqlx drivers

The driver re-exports all sqlx public API and implements the exposed traits. As a result, it can do all the drivers shipped with sqlx do, with some caveats:

• Limitations

  • separate CLI utility (sqlx-exasol instead of sqlx)
  • compile time query macros cannot work along the ones from sqlx within the same crate
  • no locking migrations support¹
  • no column nullability checks²

• Additions

  • array-like parameter binding in queries, thanks to the columnar nature of the Exasol database
  • performant & parallelizable ETL IMPORT/EXPORT jobs in CSV format through HTTP Transport

Compile-time query checks

The driver now supports compile-time query validation and can be used alongside sqlx within the same crate. Note however that derive proc-macros from sqlx are database agnostic and thus sqlx-exasol just re-exports them as-is.

CLI utility

The driver uses its own CLI utility (built on the same sqlx-cli library):

cargo install sqlx-exasol-cli

# Usage is exactly the same as sqlx-cli
sqlx-exasol database create
sqlx-exasol database drop
sqlx-exasol migrate add <name>
sqlx-exasol migrate run
cargo sqlx-exasol prepare

Connection string

The connection string is expected to be an URL with the exa:// scheme, e.g: exa://sys:exasol@localhost:8563.

See the crate level documentation for a list of supported connection string parameters.

Example

use std::env;
use sqlx_exasol::{error::*, *};

let pool = ExaPool::connect(&env::var("DATABASE_URL").unwrap()).await?;
let mut con = pool.acquire().await?;

sqlx_exasol::query("CREATE SCHEMA RUST_DOC_TEST")
    .execute(&mut *con)
    .await?;

See the crate documentation for more details and advanced examples.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions to this repository, unless explicitly stated otherwise, will be considered dual-licensed under MIT and Apache 2.0. Bugs/issues encountered can be opened here

Footnotes

1: Exasol has no advisory or database locks and simple, unnested, transactions are unfortunately not enough to define a mechanism so that concurrent migrations do not collide. This does not pose a problem when migrations are run sequentially or do not act on the same database objects.

2: Exasol does not provide the information of whether a column is nullable or not, so the driver cannot implicitly decide whether a NULL value can go into a certain database column or not until it actually tries.