diff --git a/src/catalog/src/table_source.rs b/src/catalog/src/table_source.rs
index 57ad59d892..358d015038 100644
--- a/src/catalog/src/table_source.rs
+++ b/src/catalog/src/table_source.rs
@@ -45,8 +45,8 @@ impl DfTableSourceProvider {
             catalog_manager,
             disallow_cross_schema_query,
             resolved_tables: HashMap::new(),
-            default_catalog: query_ctx.current_catalog(),
-            default_schema: query_ctx.current_schema(),
+            default_catalog: query_ctx.current_catalog().to_owned(),
+            default_schema: query_ctx.current_schema().to_owned(),
         }
     }
 
diff --git a/src/datanode/src/instance/grpc.rs b/src/datanode/src/instance/grpc.rs
index 86f291b1c0..03812817fb 100644
--- a/src/datanode/src/instance/grpc.rs
+++ b/src/datanode/src/instance/grpc.rs
@@ -65,8 +65,8 @@ impl Instance {
         ctx: QueryContextRef,
     ) -> Result<Output> {
         let catalog_list = new_dummy_catalog_list(
-            &ctx.current_catalog(),
-            &ctx.current_schema(),
+            ctx.current_catalog(),
+            ctx.current_schema(),
             self.catalog_manager.clone(),
         )
         .await?;
@@ -75,8 +75,8 @@ impl Instance {
             .decode(
                 plan_bytes.as_slice(),
                 Arc::new(catalog_list) as Arc<_>,
-                &ctx.current_catalog(),
-                &ctx.current_schema(),
+                ctx.current_catalog(),
+                ctx.current_schema(),
             )
             .await
             .context(DecodeLogicalPlanSnafu)?;
@@ -131,8 +131,8 @@ impl Instance {
     ) -> Result<Output> {
         let results = future::try_join_all(requests.inserts.into_iter().map(|insert| {
             let catalog_manager = self.catalog_manager.clone();
-            let catalog = ctx.current_catalog();
-            let schema = ctx.current_schema();
+            let catalog = ctx.current_catalog().to_owned();
+            let schema = ctx.current_schema().to_owned();
 
             common_runtime::spawn_write(async move {
                 let table_name = &insert.table_name.clone();
@@ -163,8 +163,8 @@ impl Instance {
     }
 
     async fn handle_delete(&self, request: DeleteRequest, ctx: QueryContextRef) -> Result<Output> {
-        let catalog = &ctx.current_catalog();
-        let schema = &ctx.current_schema();
+        let catalog = ctx.current_catalog();
+        let schema = ctx.current_schema();
         let table_name = &request.table_name.clone();
         let table_ref = TableReference::full(catalog, schema, table_name);
 
diff --git a/src/datanode/src/instance/sql.rs b/src/datanode/src/instance/sql.rs
index 1118bae343..df5b3eb93c 100644
--- a/src/datanode/src/instance/sql.rs
+++ b/src/datanode/src/instance/sql.rs
@@ -233,12 +233,12 @@ pub fn table_idents_to_full_name(
 ) -> Result<(String, String, String)> {
     match &obj_name.0[..] {
         [table] => Ok((
-            query_ctx.current_catalog(),
-            query_ctx.current_schema(),
+            query_ctx.current_catalog().to_owned(),
+            query_ctx.current_schema().to_owned(),
             table.value.clone(),
         )),
         [schema, table] => Ok((
-            query_ctx.current_catalog(),
+            query_ctx.current_catalog().to_owned(),
             schema.value.clone(),
             table.value.clone(),
         )),
@@ -260,7 +260,10 @@ pub fn idents_to_full_database_name(
     query_ctx: &QueryContextRef,
 ) -> Result<(String, String)> {
     match &obj_name.0[..] {
-        [database] => Ok((query_ctx.current_catalog(), database.value.clone())),
+        [database] => Ok((
+            query_ctx.current_catalog().to_owned(),
+            database.value.clone(),
+        )),
         [catalog, database] => Ok((catalog.value.clone(), database.value.clone())),
         _ => error::InvalidSqlSnafu {
             msg: format!(
diff --git a/src/datanode/src/sql/create.rs b/src/datanode/src/sql/create.rs
index 57b90cddb6..0f07becb57 100644
--- a/src/datanode/src/sql/create.rs
+++ b/src/datanode/src/sql/create.rs
@@ -48,7 +48,7 @@ impl SqlHandler {
         let schema = req.db_name;
         if self
             .catalog_manager
-            .schema_exist(&catalog, &schema)
+            .schema_exist(catalog, &schema)
             .await
             .context(CatalogSnafu)?
         {
@@ -60,7 +60,7 @@ impl SqlHandler {
         }
 
         let reg_req = RegisterSchemaRequest {
-            catalog,
+            catalog: catalog.to_owned(),
             schema: schema.clone(),
         };
         let _ = self
diff --git a/src/frontend/src/instance.rs b/src/frontend/src/instance.rs
index f2c81a6e6f..a467b7e2da 100644
--- a/src/frontend/src/instance.rs
+++ b/src/frontend/src/instance.rs
@@ -317,8 +317,8 @@ impl Instance {
         ctx: QueryContextRef,
         request: &InsertRequest,
     ) -> Result<()> {
-        let catalog_name = &ctx.current_catalog();
-        let schema_name = &ctx.current_schema();
+        let catalog_name = &ctx.current_catalog().to_owned();
+        let schema_name = &ctx.current_schema().to_owned();
         let table_name = &request.table_name;
         let columns = &request.columns;
 
@@ -374,8 +374,8 @@ impl Instance {
         columns: &[Column],
         engine: &str,
     ) -> Result<Output> {
-        let catalog_name = &ctx.current_catalog();
-        let schema_name = &ctx.current_schema();
+        let catalog_name = ctx.current_catalog();
+        let schema_name = ctx.current_schema();
 
         // Create table automatically, build schema from data.
         let create_expr = self
@@ -409,8 +409,8 @@ impl Instance {
             add_columns, table_name
         );
         let expr = AlterExpr {
-            catalog_name: ctx.current_catalog(),
-            schema_name: ctx.current_schema(),
+            catalog_name: ctx.current_catalog().to_owned(),
+            schema_name: ctx.current_schema().to_owned(),
             table_name: table_name.to_string(),
             kind: Some(Kind::AddColumns(add_columns)),
             ..Default::default()
@@ -643,7 +643,7 @@ pub fn check_permission(
         }
         Statement::ShowTables(stmt) => {
             if let Some(database) = &stmt.database {
-                validate_catalog_and_schema(&query_ctx.current_catalog(), database, query_ctx)
+                validate_catalog_and_schema(query_ctx.current_catalog(), database, query_ctx)
                     .map_err(BoxedError::new)
                     .context(SqlExecInterceptedSnafu)?;
             }
diff --git a/src/frontend/src/instance/distributed.rs b/src/frontend/src/instance/distributed.rs
index 1ea44b2a9f..5c9819be66 100644
--- a/src/frontend/src/instance/distributed.rs
+++ b/src/frontend/src/instance/distributed.rs
@@ -449,7 +449,7 @@ impl DistInstance {
         let catalog = query_ctx.current_catalog();
         if self
             .catalog_manager
-            .schema_exist(&catalog, &expr.database_name)
+            .schema_exist(catalog, &expr.database_name)
             .await
             .context(CatalogSnafu)?
         {
@@ -464,7 +464,7 @@ impl DistInstance {
         }
 
         let key = SchemaKey {
-            catalog_name: catalog.clone(),
+            catalog_name: catalog.to_owned(),
             schema_name: expr.database_name.clone(),
         };
         let value = SchemaValue {};
@@ -494,7 +494,7 @@ impl DistInstance {
         //
         // TODO(fys): when the meta invalidation cache mechanism is established, remove it.
         self.catalog_manager()
-            .invalidate_schema(&catalog, &expr.database_name)
+            .invalidate_schema(catalog, &expr.database_name)
             .await;
 
         Ok(Output::AffectedRows(1))
@@ -621,8 +621,8 @@ impl DistInstance {
         ctx: QueryContextRef,
     ) -> Result<Output> {
         let inserter = DistInserter::new(
-            ctx.current_catalog(),
-            ctx.current_schema(),
+            ctx.current_catalog().to_owned(),
+            ctx.current_schema().to_owned(),
             self.catalog_manager.clone(),
         );
         let affected_rows = inserter.grpc_insert(requests).await?;
@@ -634,8 +634,8 @@ impl DistInstance {
         request: DeleteRequest,
         ctx: QueryContextRef,
     ) -> Result<Output> {
-        let catalog = &ctx.current_catalog();
-        let schema = &ctx.current_schema();
+        let catalog = ctx.current_catalog();
+        let schema = ctx.current_schema();
         let table_name = &request.table_name;
         let table_ref = TableReference::full(catalog, schema, table_name);
 
diff --git a/src/frontend/src/instance/prom_store.rs b/src/frontend/src/instance/prom_store.rs
index 9127e4d8ad..e38bc2048d 100644
--- a/src/frontend/src/instance/prom_store.rs
+++ b/src/frontend/src/instance/prom_store.rs
@@ -132,7 +132,7 @@ impl Instance {
             let table_name = prom_store::table_name(query)?;
 
             let output = self
-                .handle_remote_query(&ctx, &catalog_name, &schema_name, &table_name, query)
+                .handle_remote_query(&ctx, catalog_name, schema_name, &table_name, query)
                 .await
                 .map_err(BoxedError::new)
                 .with_context(|_| error::ExecuteQuerySnafu {
diff --git a/src/query/src/datafusion.rs b/src/query/src/datafusion.rs
index e537518594..7f387d259d 100644
--- a/src/query/src/datafusion.rs
+++ b/src/query/src/datafusion.rs
@@ -109,9 +109,9 @@ impl DatafusionQueryEngine {
             }
         );
 
-        let default_catalog = query_ctx.current_catalog();
-        let default_schema = query_ctx.current_schema();
-        let table_name = dml.table_name.resolve(&default_catalog, &default_schema);
+        let default_catalog = &query_ctx.current_catalog().to_owned();
+        let default_schema = &query_ctx.current_schema().to_owned();
+        let table_name = dml.table_name.resolve(default_catalog, default_schema);
         let table = self.find_table(&table_name).await?;
 
         let output = self
diff --git a/src/query/src/sql.rs b/src/query/src/sql.rs
index 5754ede340..d57f83fd92 100644
--- a/src/query/src/sql.rs
+++ b/src/query/src/sql.rs
@@ -99,7 +99,7 @@ pub async fn show_databases(
     query_ctx: QueryContextRef,
 ) -> Result<Output> {
     let mut databases = catalog_manager
-        .schema_names(&query_ctx.current_catalog())
+        .schema_names(query_ctx.current_catalog())
         .await
         .context(error::CatalogSnafu)?;
 
@@ -143,11 +143,11 @@ pub async fn show_tables(
     let schema = if let Some(database) = stmt.database {
         database
     } else {
-        query_ctx.current_schema()
+        query_ctx.current_schema().to_owned()
     };
     // TODO(sunng87): move this function into query_ctx
     let mut tables = catalog_manager
-        .table_names(&query_ctx.current_catalog(), &schema)
+        .table_names(query_ctx.current_catalog(), &schema)
         .await
         .context(error::CatalogSnafu)?;
 
diff --git a/src/servers/src/grpc/handler.rs b/src/servers/src/grpc/handler.rs
index 36fe992e6b..81e12862d5 100644
--- a/src/servers/src/grpc/handler.rs
+++ b/src/servers/src/grpc/handler.rs
@@ -129,8 +129,8 @@ impl GreptimeRequestHandler {
                 .auth(
                     Identity::UserId(&username, None),
                     Password::PlainText(password.into()),
-                    &query_ctx.current_catalog(),
-                    &query_ctx.current_schema(),
+                    query_ctx.current_catalog(),
+                    query_ctx.current_schema(),
                 )
                 .await
                 .context(AuthSnafu),
diff --git a/src/servers/src/mysql/federated.rs b/src/servers/src/mysql/federated.rs
index d4007a896a..8427c462e6 100644
--- a/src/servers/src/mysql/federated.rs
+++ b/src/servers/src/mysql/federated.rs
@@ -286,7 +286,7 @@ fn check_others(query: &str, query_ctx: QueryContextRef) -> Option<Output> {
         Some(select_function("version()", &get_version()))
     } else if SELECT_DATABASE_PATTERN.is_match(query) {
         let schema = query_ctx.current_schema();
-        Some(select_function("database()", &schema))
+        Some(select_function("database()", schema))
     } else if SELECT_TIME_DIFF_FUNC_PATTERN.is_match(query) {
         Some(select_function(
             "TIMEDIFF(NOW(), UTC_TIMESTAMP())",
diff --git a/src/servers/tests/http/influxdb_test.rs b/src/servers/tests/http/influxdb_test.rs
index bba989d4e4..9b1601bad0 100644
--- a/src/servers/tests/http/influxdb_test.rs
+++ b/src/servers/tests/http/influxdb_test.rs
@@ -57,7 +57,10 @@ impl InfluxdbLineProtocolHandler for DummyInstance {
     async fn exec(&self, request: &InfluxdbRequest, ctx: QueryContextRef) -> Result<()> {
         let requests: InsertRequests = request.try_into()?;
         for expr in requests.inserts {
-            let _ = self.tx.send((ctx.current_schema(), expr.table_name)).await;
+            let _ = self
+                .tx
+                .send((ctx.current_schema().to_owned(), expr.table_name))
+                .await;
         }
 
         Ok(())
diff --git a/src/servers/tests/http/prom_store_test.rs b/src/servers/tests/http/prom_store_test.rs
index 87a0bc9869..ea9505936f 100644
--- a/src/servers/tests/http/prom_store_test.rs
+++ b/src/servers/tests/http/prom_store_test.rs
@@ -59,7 +59,7 @@ impl PromStoreProtocolHandler for DummyInstance {
     async fn write(&self, request: WriteRequest, ctx: QueryContextRef) -> Result<()> {
         let _ = self
             .tx
-            .send((ctx.current_schema(), request.encode_to_vec()))
+            .send((ctx.current_schema().to_owned(), request.encode_to_vec()))
             .await;
 
         Ok(())
@@ -67,7 +67,7 @@ impl PromStoreProtocolHandler for DummyInstance {
     async fn read(&self, request: ReadRequest, ctx: QueryContextRef) -> Result<PromStoreResponse> {
         let _ = self
             .tx
-            .send((ctx.current_schema(), request.encode_to_vec()))
+            .send((ctx.current_schema().to_owned(), request.encode_to_vec()))
             .await;
 
         let response = ReadResponse {
diff --git a/src/session/src/context.rs b/src/session/src/context.rs
index 4a2d2da2a4..3c04203263 100644
--- a/src/session/src/context.rs
+++ b/src/session/src/context.rs
@@ -79,13 +79,13 @@ impl QueryContext {
     }
 
     #[inline]
-    pub fn current_schema(&self) -> String {
-        self.current_schema.clone()
+    pub fn current_schema(&self) -> &str {
+        &self.current_schema
     }
 
     #[inline]
-    pub fn current_catalog(&self) -> String {
-        self.current_catalog.clone()
+    pub fn current_catalog(&self) -> &str {
+        &self.current_catalog
     }
 
     #[inline]
@@ -96,7 +96,7 @@ impl QueryContext {
     pub fn get_db_string(&self) -> String {
         let catalog = self.current_catalog();
         let schema = self.current_schema();
-        build_db_string(&catalog, &schema)
+        build_db_string(catalog, schema)
     }
 
     #[inline]