From e4556ce12b3b7d4863380262c4e830e7ad6dc977 Mon Sep 17 00:00:00 2001
From: Ruihang Xia <waynestxia@gmail.com>
Date: Thu, 17 Apr 2025 22:01:21 +0800
Subject: [PATCH] fix: label values potential panic (#5921)

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
---
 src/frontend/src/instance/promql.rs | 8 ++------
 tests-integration/src/test_util.rs  | 9 +++++++++
 tests-integration/tests/http.rs     | 8 ++++++++
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/frontend/src/instance/promql.rs b/src/frontend/src/instance/promql.rs
index 1dca064982..f3f276bdd9 100644
--- a/src/frontend/src/instance/promql.rs
+++ b/src/frontend/src/instance/promql.rs
@@ -161,15 +161,11 @@ impl Instance {
 
         let mut results = Vec::with_capacity(batches.iter().map(|b| b.num_rows()).sum());
         for batch in batches {
-            // Only one column the results, ensured by `prometheus::label_values_matchers_to_plan`.
+            // Only one column in results, ensured by `prometheus::label_values_matchers_to_plan`.
             let names = batch.column(0);
 
             for i in 0..names.len() {
-                let Value::String(name) = names.get(i) else {
-                    unreachable!();
-                };
-
-                results.push(name.into_string());
+                results.push(names.get(i).to_string());
             }
         }
 
diff --git a/tests-integration/src/test_util.rs b/tests-integration/src/test_util.rs
index b842c9412c..ee68b8d715 100644
--- a/tests-integration/src/test_util.rs
+++ b/tests-integration/src/test_util.rs
@@ -503,6 +503,9 @@ pub async fn setup_test_prom_app_with_frontend(
     let sql =
         "INSERT INTO demo_metrics(idc, val, ts) VALUES ('idc1', 1.1, 0), ('idc2', 2.1, 600000)";
     run_sql(sql, &instance).await;
+    // insert a row with empty label
+    let sql = "INSERT INTO demo_metrics(val, ts) VALUES (1.1, 0)";
+    run_sql(sql, &instance).await;
 
     // build physical table
     let sql = "CREATE TABLE phy2 (ts timestamp(9) time index, val double, host string primary key) engine=metric with ('physical_metric_table' = '')";
@@ -512,6 +515,12 @@ pub async fn setup_test_prom_app_with_frontend(
     let sql = "INSERT INTO demo_metrics_with_nanos(idc, val, ts) VALUES ('idc1', 1.1, 0)";
     run_sql(sql, &instance).await;
 
+    // a mito table with non-prometheus compatible values
+    let sql = "CREATE TABLE mito (ts timestamp(9) time index, val double, host bigint primary key) engine=mito";
+    run_sql(sql, &instance).await;
+    let sql = "INSERT INTO mito(host, val, ts) VALUES (1, 1.1, 0)";
+    run_sql(sql, &instance).await;
+
     let http_opts = HttpOptions {
         addr: format!("127.0.0.1:{}", ports::get_port()),
         ..Default::default()
diff --git a/tests-integration/tests/http.rs b/tests-integration/tests/http.rs
index 8ef27cdbf0..9e369e654d 100644
--- a/tests-integration/tests/http.rs
+++ b/tests-integration/tests/http.rs
@@ -765,6 +765,13 @@ pub async fn test_prom_http_api(store_type: StorageType) {
     assert!(prom_resp.error.is_none());
     assert!(prom_resp.error_type.is_none());
 
+    // query non-string value
+    let res = client
+        .get("/v1/prometheus/api/v1/label/host/values?match[]=mito")
+        .send()
+        .await;
+    assert_eq!(res.status(), StatusCode::OK);
+
     // query `__name__` without match[]
     // create a physical table and a logical table
     let res = client
@@ -794,6 +801,7 @@ pub async fn test_prom_http_api(store_type: StorageType) {
             "demo_metrics".to_string(),
             "demo_metrics_with_nanos".to_string(),
             "logic_table".to_string(),
+            "mito".to_string(),
             "numbers".to_string()
         ])
     );