claude-memory/graph/fixes/fix-sqlx-in-memory-sqlite-pool-requires-max-connections1-1b71b1.md

id	type	title	tags	importance	confidence	created	updated
1b71b163-b56f-4226-9731-a76ef245e532	fix	Fix: sqlx in-memory SQLite pool requires max_connections=1	sba-scouting rust sqlx sqlite testing fix in-memory	0.8	0.8	2026-03-02T02:08:46.895029+00:00	2026-03-02T02:08:46.895029+00:00

sqlx In-Memory SQLite Pool: max_connections Must Be 1

Problem

Integration tests using :memory: SQLite failed with "no such table" errors after wrapping create_tables in a transaction.

Root Cause

With max_connections > 1, each connection in the pool gets its own separate in-memory database. A transaction on connection A (e.g. pool.begin() for create_tables) is invisible to queries on connection B. In-memory SQLite databases are per-connection — there is no shared state across connections.

Fix

Detect :memory: path and force max_connections(1). Also skip WAL journal mode for in-memory DBs (WAL requires a file).

let pool = if db_path == ":memory:" {
    SqlitePoolOptions::new()
        .max_connections(1)
        .connect(":memory:")
        .await?
} else {
    SqlitePoolOptions::new()
        .max_connections(5)
        .connect(&format!("sqlite:{db_path}"))
        .await?
};

// Only set WAL for file-backed DBs
if db_path != ":memory:" {
    sqlx::query("PRAGMA journal_mode=WAL").execute(&pool).await?;
}

Impact

All 5 integration tests were broken until this was applied. Applies to any test setup using create_tables inside a transaction with a shared pool.