nautechsystems/nautilus_trader · error

Failed to load order position index: {e}

Error message

Failed to load order position index: {e}

What it means

This error is raised by `load_index_order_position` when the SQLX query that reads all rows of the `order_position_index` table fails. The library wraps the underlying sqlx error via `anyhow::anyhow!` so callers get a single anyhow::Error carrying the database failure message. It means the SELECT against the PostgreSQL pool could not be executed or fetched.

Source

Thrown at crates/infrastructure/src/sql/queries.rs:1557

    ///
    /// # Errors
    ///
    /// Returns an error if the SQL SELECT or iteration fails.
    pub async fn load_index_order_position(
        pool: &PgPool,
    ) -> anyhow::Result<AHashMap<ClientOrderId, PositionId>> {
        let mut map: AHashMap<ClientOrderId, PositionId> = AHashMap::new();
        let result = sqlx::query_as::<_, OrderPositionIndexRow>(
            r#"
            SELECT
                client_order_id AS "client_order_id",
                position_id AS "position_id"
            FROM "order_position_index"
        "#,
        )
        .fetch_all(pool)
        .await
        .map_err(|e| anyhow::anyhow!("Failed to load order position index: {e}"))?;

        for row in result {
            map.insert(row.client_order_id, row.position_id);
        }
        Ok(map)
    }

    /// Inserts a `Signal` entry via the provided `pool`.
    ///
    /// # Errors
    ///
    /// Returns an error if the SQL INSERT operation fails.
    pub async fn add_signal(pool: &PgPool, signal: &Signal) -> anyhow::Result<()> {
        sqlx::query(
            r#"
            INSERT INTO "signal" (
                name, value, ts_event, ts_init, created_at, updated_at
            ) VALUES (

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Verify PostgreSQL connectivity and credentials in the pool config (test with psql).
  2. Apply migrations so the `order_position_index` table exists (check the sqlx migrations directory).
  3. Inspect the inner sqlx error message embedded in `{e}` for the exact DB-level cause.
  4. Retry on transient errors; enable pool acquire_timeout and max_lifetime tuning if idle disconnects recur.

Example fix

// before
let map = load_index_order_position(&pool).await?;
// after
match load_index_order_position(&pool).await {
    Ok(map) => map,
    Err(e) => { tracing::error!("order position index load failed: {e:#}"); return Err(e); }
}
Defensive patterns

Strategy: try-catch

Validate before calling

// check table exists before loading
let exists: bool = sqlx::query_scalar(
    "SELECT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'order_position_index')")
    .fetch_one(pool).await?;
anyhow::ensure!(exists, "order_position_index table missing; run migrations");

Try / catch

match load_index_order_position(&pool).await {
    Ok(map) => map,
    Err(e) => {
        tracing::error!("index load failed: {e:#}");
        if is_transient(&e) { /* retry with backoff */ }
        return Err(e);
    }
}

Prevention

When it happens

Trigger: Calling `load_index_order_position(pool)` when the PostgreSQL server is unreachable, the `order_position_index` table does not exist (missing migration), the connection pool is exhausted/closed, credentials are wrong, or a transient network failure occurs during `fetch_all`.

Common situations: Running against a database where migrations were never applied or were partially applied; connection drops after idle timeouts; wrong DATABASE_URL or insufficient privileges to SELECT from the table; connecting to a database of a different schema version.

Understand the failure class

Background: "query failed", "%w: SQL error" — wrapped database query errors in Go libraries explained — this error's family across 3 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/5c9ce9e864a46ac7. Report an issue: GitHub.