From 5cec0d4e3aa85b2be99f02a9a3ce5a1bac2223ef Mon Sep 17 00:00:00 2001
From: yihong <zouzou0208@gmail.com>
Date: Tue, 12 Aug 2025 14:38:01 +0800
Subject: [PATCH] fix: http and tql should return the same value for nuknown
 (#6718)

Signed-off-by: yihong0618 <zouzou0208@gmail.com>
---
 src/servers/src/http/result/prometheus_resp.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/servers/src/http/result/prometheus_resp.rs b/src/servers/src/http/result/prometheus_resp.rs
index bba507b676..50af912122 100644
--- a/src/servers/src/http/result/prometheus_resp.rs
+++ b/src/servers/src/http/result/prometheus_resp.rs
@@ -185,6 +185,14 @@ impl PrometheusJsonResponse {
         metric_name: Option<String>,
         result_type: ValueType,
     ) -> Result<PrometheusResponse> {
+        // Return empty result if no batches
+        if batches.iter().next().is_none() {
+            return Ok(PrometheusResponse::PromData(PromData {
+                result_type: result_type.to_string(),
+                ..Default::default()
+            }));
+        }
+
         // infer semantic type of each column from schema.
         // TODO(ruihang): wish there is a better way to do this.
         let mut timestamp_column_index = None;