What causes "Failed to load position ids: {e}" in nautechsystems/nautilus_trader?

Inspect the wrapped sqlx error for the root cause.

Failed to load position ids: {e}

Error message

Failed to load position ids: {e}

What it means

load_positions first queries the distinct position_ids from the position events table; if that SELECT fails the sqlx error is wrapped in this message. No positions are returned because the id enumeration itself failed.

Source

Thrown at crates/infrastructure/src/sql/queries.rs:991

    /// # Errors
    ///
    /// Returns an error if loading position IDs or replaying any position fails.
    pub async fn load_positions(pool: &PgPool) -> anyhow::Result<Vec<Position>> {
        let position_ids: Vec<PositionId> = sqlx::query(
            r#"
            SELECT DISTINCT position_id
            FROM "position_event"
            ORDER BY position_id ASC
        "#,
        )
        .fetch_all(pool)
        .await
        .map(|rows| {
            rows.into_iter()
                .map(|row| PositionId::from(row.get::<&str, _>(0)))
                .collect()
        })
        .map_err(|e| anyhow::anyhow!("Failed to load position ids: {e}"))?;

        let mut positions = Vec::new();

        for id in position_ids {
            match Self::load_position(pool, &id).await {
                Ok(Some(position)) => positions.push(position),
                Ok(None) => log::error!("Position not found: {id}"),
                Err(e) => log::error!("Failed to load position {id}: {e}"),
            }
        }

        Ok(positions)
    }

    async fn insert_position_event(
        transaction: &mut Transaction<'_, Postgres>,
        event: &OrderFilled,
    ) -> anyhow::Result<()> {

View on GitHub (pinned to 18893faf8b)

Solutions

Inspect the wrapped sqlx error for the root cause.
Run the nautilus SQL migrations so the position tables exist.
Confirm the venue/instance filters match data actually written to this database.
Verify connectivity and privileges, then retry if the failure was transient.

Defensive patterns

Strategy: retry

Validate before calling

sqlx::query("SELECT 1 FROM position_event LIMIT 1").fetch_optional(&pool).await?;

Try / catch

match load_positions(&pool, &venue).await {
    Err(e) if is_transient_db_error(&e) => retry_with_backoff(3),
    other => other,
}

Prevention

Run migrations before first use of the SQL cache.
Confirm venue/instance filters match the data in this database.
Grant the DB user the required SELECT privileges.

When it happens

Trigger: Calling DatabaseQuery::load_positions(pool, venue) and the id query errors: missing table, connection failure, or SQL error wrapped via anyhow.

Common situations: Database not migrated; wrong venue filter against an empty/uninitialized schema; connectivity loss at query time; insufficient SELECT privileges.

Understand the failure class

Background: Database query failed: Internal Server Error 500s wrapping SQL, Prisma, and connection failures — what to check first — this error's family across 16 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/553c65375eb8aa3c. Report an issue: GitHub.