Merge pull request #3208 from influxdata/er/fix/grpc_influxql_multiple_time

fix: ensure time column not returned

query/src/frontend/influxrpc.rs

@@ -895,6 +895,11 @@ impl InfluxRpcPlanner {
             })
             .collect::<Vec<_>>();
 
+        // If the projection is empty then there is no plan to execute.
+        if select_exprs.is_empty() {
+            return Ok(None);
+        }
+
         let plan = plan_builder
             .project(select_exprs)
             .context(BuildingPlan)?

query_tests/src/influxrpc/tag_keys.rs

@@ -46,6 +46,15 @@ where
     }
 }
 
+#[tokio::test]
+async fn list_tag_columns_with_no_tags() {
+    let predicate = PredicateBuilder::default().build();
+    run_tag_keys_test_case(OneMeasurementNoTags {}, predicate, vec![]).await;
+
+    let predicate = PredicateBuilder::default().timestamp_range(0, 1000).build();
+    run_tag_keys_test_case(OneMeasurementNoTags {}, predicate, vec![]).await;
+}
+
 #[tokio::test]
 async fn list_tag_columns_no_predicate() {
     let predicate = PredicateBuilder::default().build();

query_tests/src/scenarios.rs

@@ -223,6 +223,25 @@ impl DbSetup for OneMeasurementRealisticTimes {
     }
 }
 
+#[derive(Debug)]
+pub struct OneMeasurementNoTags {}
+#[async_trait]
+impl DbSetup for OneMeasurementNoTags {
+    async fn make(&self) -> Vec<DbScenario> {
+        let partition_key = "1970-01-01T00";
+
+        let lp_lines = vec![
+            "h2o temp=70.4 100",
+            "h2o temp=72.4 250",
+            "h2o temp=50.4 200",
+            "h2o level=200.0 300",
+        ];
+
+        // return all possible scenarios a chunk: MUB open, MUB frozen, RUB, RUB & OS, OS
+        all_scenarios_for_one_chunk(vec![], vec![], lp_lines, "h2o", partition_key).await
+    }
+}
+
 #[derive(Debug)]
 pub struct OneMeasurementManyNullTags {}
 #[async_trait]