Function explain_pushdown_future_inner 

pub(crate) async fn explain_pushdown_future_inner<I: IntoIterator<Item = (GlobalId, MfpPlan<LirScalarExpr>)>>(
    session: &Session,
    catalog: &Catalog,
    storage_collections: &Arc<dyn StorageCollections + Send + Sync>,
    as_of: Antichain<Timestamp>,
    mz_now: ResultSpec<'static>,
    imports: I,
) -> impl Future<Output = Result<ExecuteResponse, AdapterError>> + use<I>

Returns a future that will execute EXPLAIN FILTER PUSHDOWN, i.e., compute the filter pushdown statistics for the given collections with the given MFPs.

The coordinator calls this for materialized views and the frontend peek sequencing for SELECTs, so it takes only what it needs instead of the Coordinator.