Function plan_values

src/sql/src/plan/query.rs:2076–2148

Plans a `VALUES` clause that appears in a `SELECT` statement.

(
    qcx: &QueryContext,
    values: &[Vec<Expr<Aug>>],
)

/// Plans a `VALUES` clause that appears in a `SELECT` statement.
fn plan_values(
    qcx: &QueryContext,
    values: &[Vec<Expr<Aug>>],
) -> Result<(HirRelationExpr, Scope), PlanError> {
    assert!(!values.is_empty());

    let ecx = &ExprContext {
        qcx,
        name: "VALUES",
        scope: &Scope::empty(),
        relation_type: &SqlRelationType::empty(),
        allow_aggregates: false,
        allow_subqueries: true,
        allow_parameters: true,
        allow_windows: false,
    };

    let ncols = values[0].len();
    let nrows = values.len();

    // Arrange input expressions by columns, not rows, so that we can
    // call `coerce_homogeneous_exprs` on each column.
    let mut cols = vec![vec![]; ncols];
    for row in values {
        if row.len() != ncols {
            sql_bail!(
                "VALUES expression has varying number of columns: {} vs {}",
                row.len(),
                ncols
            );
        }
        for (i, v) in row.iter().enumerate() {
            cols[i].push(v);
        }
    }

    // Plan each column.
    let mut col_iters = Vec::with_capacity(ncols);
    let mut col_types = Vec::with_capacity(ncols);
    for col in &cols {
        let col = coerce_homogeneous_exprs(ecx, plan_exprs(ecx, col)?, None)?;
        let mut col_type = ecx.column_type(&col[0]);
        for val in &col[1..] {
            col_type = col_type.sql_union(&ecx.column_type(val))?; // HIR deliberately not using `union`
        }
        col_types.push(col_type);
        col_iters.push(col.into_iter());
    }

    // Build constant relation.
    let mut exprs = vec![];
    for _ in 0..nrows {
        for i in 0..ncols {
            exprs.push(col_iters[i].next().unwrap());
        }
    }
    let out = HirRelationExpr::CallTable {
        func: TableFunc::Wrap {