remove unused code.

query_engine/src/datafusion_impl/logical_optimizer/mod.rs

@@ -24,38 +24,3 @@ use query_frontend::plan::QueryPlan;
 use snafu::ResultExt;
 
 use crate::error::*;
-
-/// LogicalOptimizer transform the QueryPlan into a potentially more efficient
-/// plan
-pub trait LogicalOptimizer {
-    // TODO(yingwen): Maybe support other plans
-    fn optimize(&mut self, plan: QueryPlan) -> Result<QueryPlan>;
-}
-
-pub struct LogicalOptimizerImpl {
-    ctx: SessionContext,
-}
-
-impl LogicalOptimizerImpl {
-    pub fn with_context(ctx: SessionContext) -> Self {
-        Self { ctx }
-    }
-}
-
-impl LogicalOptimizer for LogicalOptimizerImpl {
-    fn optimize(&mut self, plan: QueryPlan) -> Result<QueryPlan> {
-        // TODO(yingwen): Avoid clone the plan multiple times during optimization
-        let QueryPlan {
-            mut df_plan,
-            tables,
-        } = plan;
-        df_plan = self
-            .ctx
-            .state()
-            .optimize(&df_plan)
-            .box_err()
-            .context(LogicalOptimizerWithCause { msg: None })?;
-
-        Ok(QueryPlan { df_plan, tables })
-    }
-}