Crate rudb 

The embedding API: connections, prepared statements, configuration and results.

Rank 13 in the layer rule. See xtask/layers.toml and spec/18-package-layout.md.

This is the crate somebody who wants a database depends on. Everything below it is an implementation detail that happens to be published, and everything above it is a different way of reaching this same API: rudb-c-api is this over the C ABI and rudb-cli is this behind a prompt.

use rudb::Database;
use rudb_common::{Field, LogicalType, Value};

let mut db = Database::new();
db.create_table("t", vec![Field::new("x", LogicalType::Integer)])?;
db.append("t", &[vec![Value::Integer(1)], vec![Value::Integer(7)]])?;

let result = db.query("SELECT x FROM t WHERE x > 5")?;
assert_eq!(result.len(), 1);
assert_eq!(result.value_at(0, 0), Value::Integer(7));

What a query is today

Parse, bind, optimize, execute. The optimizer is one pass, which is column pruning, so a scan reads the columns something above it asks for and the plan is otherwise the shape the binder built it. The rest of spec/09-optimizer.md’s sequence is M1 work. There are no transactions, and rudb-txn is in the dependency list for the same reason: the seam is where it will be and nothing goes through it yet.

There is also no CREATE TABLE and no INSERT, because the M0 parser handles SELECT and nothing else. Database::create_table and Database::append are how rows get in, and they are a real part of the API rather than a test helper, since an embedded analytical database gets most of its data from a program rather than from a string of SQL. When the DDL statements arrive they bind to the same catalog calls these make.

Threading

Database::query takes &self. Binding reads the catalog and running a plan reads the tables, so two queries can run at once against one database and the compiler enforces that nothing is being written while they do. Writing takes &mut self, which is the whole of the concurrency story until rudb-txn has one.

Structs

Database

An in process database.

QueryResult

The rows a query produced, with the names and types of its columns.

Statement

One statement out of a script, and where it started.

Functions

is_complete

Whether a script ends on a statement boundary.

statements

Every statement in a script, in order.