Method explain_to_plan

datafusion/sql/src/statement.rs:2005–2058

Generate a plan for EXPLAIN ... that will print out a plan Note this is the sqlparser explain statement, not the datafusion `EXPLAIN` statement.

(
        &self,
        verbose: bool,
        analyze: bool,
        format: Option<String>,
        statement: DFStatement,
    )

    /// Note this is the sqlparser explain statement, not the
    /// datafusion `EXPLAIN` statement.
    fn explain_to_plan(
        &self,
        verbose: bool,
        analyze: bool,
        format: Option<String>,
        statement: DFStatement,
    ) -> Result<LogicalPlan> {
        let plan = self.statement_to_plan(statement)?;
        if matches!(plan, LogicalPlan::Explain(_)) {
            return plan_err!("Nested EXPLAINs are not supported");
        }

        let plan = Arc::new(plan);
        let schema = LogicalPlan::explain_schema();
        let schema = schema.to_dfschema_ref()?;

        if verbose && format.is_some() {
            return plan_err!("EXPLAIN VERBOSE with FORMAT is not supported");
        }

        if analyze {
            if format.is_some() {
                return plan_err!("EXPLAIN ANALYZE with FORMAT is not supported");
            }
            Ok(LogicalPlan::Analyze(Analyze {
                verbose,
                input: plan,
                schema,
            }))
        } else {
            let stringified_plans =
                vec![plan.to_stringified(PlanType::InitialLogicalPlan)];

            // default to configuration value
            // verbose mode only supports indent format
            let options = self.context_provider.options();
            let format = if verbose {
                ExplainFormat::Indent
            } else if let Some(format) = format {
                ExplainFormat::from_str(&format)?
            } else {
                options.explain.format.clone()
            };

            Ok(LogicalPlan::Explain(Explain {
                verbose,
                explain_format: format,
                plan,
                stringified_plans,
                schema,
                logical_optimization_succeeded: false,
            }))
        }
    }

    fn show_variable_to_plan(&self, variable: &[Ident]) -> Result<LogicalPlan> {
        if !self.has_table("information_schema", "df_settings") {