alopex-sql

alopex-sql は Alopex の SQL レイヤーを提供します。v0.5.0 では GROUP BY/HAVING と集約関数をサポートします。

Quick Start

use std::sync::{Arc, RwLock};

use alopex_core::kv::memory::MemoryKV;
use alopex_sql::catalog::MemoryCatalog;
use alopex_sql::dialect::AlopexDialect;
use alopex_sql::executor::{ExecutionResult, Executor};
use alopex_sql::parser::Parser;
use alopex_sql::planner::Planner;

let sql = r#"
    CREATE TABLE sales (region TEXT, amount INT);
    INSERT INTO sales (region, amount) VALUES ('us', 10), ('us', 20), ('eu', 7);
    SELECT region, SUM(amount) FROM sales GROUP BY region;
"#;

let dialect = AlopexDialect;
let statements = Parser::parse_sql(&dialect, sql).unwrap();

let catalog = Arc::new(RwLock::new(MemoryCatalog::new()));
let store = Arc::new(MemoryKV::new());
let mut executor = Executor::new(store, catalog.clone());

for stmt in statements {
    let plan = {
        let guard = catalog.read().unwrap();
        Planner::new(&*guard).plan(&stmt).unwrap()
    };
    let _ = executor.execute(plan).unwrap();
}

GROUP BY / HAVING

SELECT category, COUNT(*) FROM products GROUP BY category;
SELECT category, COUNT(*) FROM products GROUP BY category HAVING COUNT(*) > 10;
SELECT category, COUNT(*) FROM products GROUP BY category ORDER BY COUNT(*) DESC;

Supported Aggregate Functions

• COUNT(*)
• COUNT(column)
• COUNT(DISTINCT column)
• SUM(column) (numeric)
• TOTAL(column) (numeric, returns 0.0 for all-NULL)
• AVG(column) (numeric)
• MIN(column) / MAX(column) (comparable types)
• GROUP_CONCAT(column) / GROUP_CONCAT(column, separator)
• STRING_AGG(column, separator)

Limitations

• JOIN/Subquery/Window 関数は未対応。
• SUM/AVG/MIN/MAX の DISTINCT は未対応。
• GROUP BY の式は現状カラム参照のみを想定。

Error Scenarios

• ColumnNotFound: 存在しないカラムを GROUP BY で参照した場合。
• TypeMismatch: SUM/AVG に非数値型、GROUP_CONCAT に非 TEXT を指定した場合。
• InvalidExpression: HAVING や SELECT で GROUP BY に含まれない非集約列を参照した場合。
• ResourceExhausted: グループ数が上限を超えた場合（デフォルト 1,000,000）。