diff --git a/server/src/grpc/storage_service/route.rs b/server/src/grpc/storage_service/route.rs
index a38f4854e9..ad22ef5927 100644
--- a/server/src/grpc/storage_service/route.rs
+++ b/server/src/grpc/storage_service/route.rs
@@ -2,7 +2,12 @@
 
 //! Route handler
 
-use ceresdbproto::storage::{RouteRequest, RouteResponse};
+use std::collections::HashMap;
+
+use ceresdbproto::storage::{Route, RouteRequest, RouteResponse};
+use error::ErrNoCause;
+use http::StatusCode;
+use snafu::OptionExt;
 
 use crate::grpc::storage_service::{
     error::{self, Result},
@@ -13,11 +18,61 @@ pub async fn handle_route<Q>(
     ctx: &HandlerContext<'_, Q>,
     req: RouteRequest,
 ) -> Result<RouteResponse> {
+    // TODO: the case sensitive mode with quoted is not supported now, all table
+    // name will be converted to lowercase.
+
+    // Get normalized metrics to original one's mapping.
+    let normalized_to_origin: HashMap<_, _> = req
+        .metrics
+        .iter()
+        .enumerate()
+        .map(|(idx, metric)| (metric.to_ascii_lowercase(), idx))
+        .collect();
+    let mut origins = req.metrics;
+
+    // Route using normalized metrics.
+    let normalized_metrics: Vec<_> = normalized_to_origin
+        .iter()
+        .map(|(k, _)| k.clone())
+        .collect();
+    let req = RouteRequest {
+        metrics: normalized_metrics,
+    };
+
+    // Replace the normalized metrics in response to origin ones to avoiding
+    // exposing this behavior to client.
     let routes = ctx.router.route(ctx.tenant(), req).await?;
+    let mut routes_with_origins = Vec::with_capacity(routes.len());
+    let origins_len = origins.len();
+    for route in routes {
+        let idx = normalized_to_origin
+            .get(&route.metric)
+            .with_context(|| ErrNoCause {
+                code: StatusCode::INTERNAL_SERVER_ERROR,
+                msg: format!(
+                    "unknown normalized metric name while finding its origin, metric:{}",
+                    route.metric
+                ),
+            })?;
+
+        let origin = origins.get_mut(*idx).with_context(|| ErrNoCause {
+            code: StatusCode::INTERNAL_SERVER_ERROR,
+            msg: format!(
+                "impossible to find nothing through idx, idx:{}, origins len:{}",
+                idx, origins_len
+            ),
+        })?;
+
+        routes_with_origins.push(Route {
+            metric: std::mem::take(origin),
+            endpoint: route.endpoint,
+            ext: route.ext,
+        });
+    }
 
     let resp = RouteResponse {
         header: Some(error::build_ok_header()),
-        routes,
+        routes: routes_with_origins,
     };
 
     Ok(resp)
diff --git a/server/src/grpc/storage_service/write.rs b/server/src/grpc/storage_service/write.rs
index 17ccaf7068..9368b335b0 100644
--- a/server/src/grpc/storage_service/write.rs
+++ b/server/src/grpc/storage_service/write.rs
@@ -115,15 +115,15 @@ async fn write_request_to_insert_plan<Q: QueryExecutor + 'static>(
     let mut plan_vec = Vec::with_capacity(write_request.metrics.len());
 
     for write_metric in write_request.metrics {
-        let table_name = &write_metric.metric;
-        let mut table = try_get_table(ctx, table_name)?;
+        let normalized_table_name = &write_metric.metric.to_ascii_lowercase();
+        let mut table = try_get_table(ctx, normalized_table_name)?;
 
         if table.is_none() {
             if let Some(config) = ctx.schema_config {
                 if config.auto_create_tables {
                     create_table(ctx, &write_metric, request_id).await?;
                     // try to get table again
-                    table = try_get_table(ctx, table_name)?;
+                    table = try_get_table(ctx, normalized_table_name)?;
                 }
             }
         }
@@ -139,7 +139,7 @@ async fn write_request_to_insert_plan<Q: QueryExecutor + 'static>(
                     msg: format!(
                         "Table not found, tenant:{}, table:{}",
                         ctx.tenant(),
-                        table_name
+                        normalized_table_name
                     ),
                 }
                 .fail();
diff --git a/sql/src/ast.rs b/sql/src/ast.rs
index d2a6fe1264..b9fbec0570 100644
--- a/sql/src/ast.rs
+++ b/sql/src/ast.rs
@@ -3,7 +3,7 @@
 //! SQL statement
 
 use sqlparser::ast::{
-    ColumnDef, Ident, ObjectName, SqlOption, Statement as SqlStatement, TableConstraint,
+    ColumnDef, ObjectName, SqlOption, Statement as SqlStatement, TableConstraint,
 };
 
 /// Statement representations
@@ -33,14 +33,6 @@ impl TableName {
     pub fn is_empty(&self) -> bool {
         self.0 .0.is_empty()
     }
-
-    // Normalize an identifer to a lowercase string unless the identifier is quoted.
-    fn normalize_ident(id: &Ident) -> String {
-        match id.quote_style {
-            Some(_) => id.value.clone(),
-            None => id.value.to_ascii_lowercase(),
-        }
-    }
 }
 
 impl ToString for TableName {
@@ -48,7 +40,7 @@ impl ToString for TableName {
         self.0
              .0
             .iter()
-            .map(Self::normalize_ident)
+            .map(|id| id.value.to_ascii_lowercase())
             .collect::<Vec<_>>()
             .join(".")
     }