Function plan_root_query

src/sql/src/plan/query.rs:131–182

(
    scx: &StatementContext,
    mut query: Query<Aug>,
    lifetime: QueryLifetime,
)

/// applying the returned `RowSetFinishing`.
#[mz_ore::instrument(target = "compiler", level = "trace", name = "ast_to_hir")]
pub fn plan_root_query(
    scx: &StatementContext,
    mut query: Query<Aug>,
    lifetime: QueryLifetime,
) -> Result<PlannedRootQuery<HirRelationExpr>, PlanError> {
    transform_ast::transform(scx, &mut query)?;
    let mut qcx = QueryContext::root(scx, lifetime);
    let PlannedQuery {
        mut expr,
        scope,
        order_by,
        limit,
        offset,
        project,
        group_size_hints,
    } = plan_query(&mut qcx, &query)?;

    let mut finishing = RowSetFinishing {
        limit,
        offset,
        project,
        order_by,
    };

    // Attempt to push the finishing's ordering past its projection. This allows
    // data to be projected down on the workers rather than the coordinator. It
    // also improves the optimizer's demand analysis, as the optimizer can only
    // reason about demand information in `expr` (i.e., it can't see
    // `finishing.project`).
    try_push_projection_order_by(&mut expr, &mut finishing.project, &mut finishing.order_by);

    if lifetime.is_maintained() {
        expr.finish_maintained(&mut finishing, group_size_hints);
    }

    let typ = qcx.relation_type(&expr);
    let typ = SqlRelationType::new(
        finishing
            .project
            .iter()
            .map(|i| typ.column_types[*i].clone())
            .collect(),
    );
    let desc = RelationDesc::new(typ, scope.column_names());

    Ok(PlannedRootQuery {
        expr,
        desc,
        finishing,
        scope,
    })
}

/// Attempts to push a projection through an order by.
///