What causes "query addition to connection in MockAdapter" in dbt-labs/dbt-core?

Use a real database-backed adapter (DuckDB, Postgres, etc.) whenever SQL execution is expected.

query addition to connection in MockAdapter

Error message

query addition to connection in MockAdapter

What it means

AdapterImpl::add_query panics when the adapter is a MockAdapter (mock_state().is_some()) and an executable query is added to its connection. MockAdapter is intended for parsing/planning without a real database, so executing SQL against it is unsupported by design.

Source

Thrown at crates/dbt-adapter/src/adapter/adapter_impl.rs:960

            token,
        )
    }

    /// SQLAdapter https://github.com/dbt-labs/dbt-adapters/blob/0efd8d3d1081e1ab43e38797d5104f7b424a6284/dbt-adapters/src/dbt/adapters/sql/impl.py#L55
    /// BigQueryAdapter https://github.com/dbt-labs/dbt-adapters/blob/0efd8d3d1081e1ab43e38797d5104f7b424a6284/dbt-bigquery/src/dbt/adapters/bigquery/impl.py#L573
    #[allow(clippy::too_many_arguments)]
    pub fn add_query(
        &self,
        state: &State,
        conn: &'_ mut dyn Connection,
        sql: &str,
        auto_begin: bool,
        bindings: Option<&Value>,
        abridge_sql_log: bool,
        token: CancellationToken,
    ) -> AdapterResult<()> {
        if self.mock_state().is_some() {
            unimplemented!("query addition to connection in MockAdapter")
        }
        let sql = if let Some(bindings) = bindings {
            Cow::Owned(format_sql_with_bindings(
                self.adapter_type(),
                sql,
                bindings,
            )?)
        } else {
            Cow::Borrowed(sql)
        };
        let ctx = query_ctx_from_state(state)?.with_desc("add_query adapter call");
        match self.inner_adapter() {
            Replay(_, replay) => replay.replay_add_query(
                &ctx,
                conn,
                sql.as_ref(),
                auto_begin,
                bindings,

View on GitHub (pinned to 0267ce9170)

Solutions

Use a real database-backed adapter (DuckDB, Postgres, etc.) whenever SQL execution is expected.
Audit the calling macro/model so no execute path runs under parse/compile with a mock adapter.
If MockAdapter should support query logging, implement the mock branch in add_query to record the SQL instead of panicking.

Example fix

// before
if self.mock_state().is_some() {
    unimplemented!("query addition to connection in MockAdapter")
}
// after
if let Some(state) = self.mock_state() {
    state.record_query(&sql);
    return Ok(());
}

Defensive patterns

Strategy: validation

Validate before calling

if adapter.is_mock() {
    return Err("cannot execute SQL: adapter is in mock mode".into());
}

Type guard

fn can_execute(adapter: &AdapterImpl) -> bool { adapter.mock_state().is_none() }

Prevention

Only use MockAdapter for parse/compile; use a real adapter (e.g. DuckDB) for run/execute
Assert execution paths never run under `dbt parse` in CI
Add a capability check before invoking add_query

When it happens

Trigger: Calling add_query (execute/bind SQL with auto_begin, bindings, cancellation token) on an adapter constructed in mock mode, e.g. during `dbt parse` flows or tests that later reach a code path that executes SQL.

Common situations: Running `dbt compile`/`parse` with a mock adapter while a macro or model invokes execute()/run_query; unit tests that accidentally use MockAdapter for execution paths.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/8d6a1b97b76e8fee. Report an issue: GitHub.