/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at
http://mozilla.org/MPL/2.0/. */
//! The SQLite database schema.
use std::num::NonZeroU32;
use rusqlite::Transaction;
use crate::skv::connection::ConnectionMigrator;
/// The schema for a physical SQLite database that contains many
/// named logical databases.
#[derive(Debug)]
pub struct Schema;
impl ConnectionMigrator for Schema {
const MAX_SCHEMA_VERSION: u32 = 1;
type Error = SchemaError;
fn create(tx: &mut Transaction<'_>) -> Result<(), Self::Error> {
tx.execute_batch(
"CREATE TABLE dbs(
id INTEGER PRIMARY KEY,
-- We expect each physical database to have just a handful of
-- logical databases, so a UNIQUE constraint is OK here.
name TEXT UNIQUE NOT NULL
);
CREATE TABLE data(
-- Foreign key references don't create new automatic indexes,
-- but `db_id` is the leftmost column of the primary key,
-- so the primary key index is usable for cascading deletes.
-- `db_id` and `text` also omit NOT NULL, because
-- WITHOUT ROWID tables enforce NOT NULL for primary keys.
db_id INTEGER REFERENCES dbs(id) ON DELETE CASCADE,
key TEXT,
value BLOB NOT NULL, -- Encoded in JSONB format.
PRIMARY KEY(db_id, key)
) WITHOUT ROWID;
CREATE TABLE meta(
key TEXT PRIMARY KEY,
value NOT NULL
) WITHOUT ROWID;
",
)?;
Ok(())
}
fn upgrade(_: &mut Transaction<'_>, to_version: NonZeroU32) -> Result<(), Self::Error> {
Err(SchemaError::UnsupportedSchemaVersion(to_version.get()))
}
}
#[derive(thiserror::Error, Debug)]
pub enum SchemaError {
#[error("unsupported schema version: {0}")]
UnsupportedSchemaVersion(u32),
#[error("sqlite: {0}")]
Sqlite(#[from] rusqlite::Error),
}
