From 66a1ff5cc732809dfe09b4bc1335d7d1ff9bc88a Mon Sep 17 00:00:00 2001
From: Dipeshsharma2005 <dipeshsharma001s@gmail.com>
Date: Tue, 6 Jan 2026 14:42:34 +0530
Subject: [PATCH] Fix case-sensitive CONTAINS for tag filtering

Normalize tag values during CONTAINS evaluation so that
tag-based filtering behaves case-insensitively, consistent
with timeseries name filtering.
---
 .../iotdb/db/schemaengine/schemaregion/tag/TagManager.java | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/tag/TagManager.java b/iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/tag/TagManager.java
index 86e2a6563143..f3c685b846bf 100644
--- a/iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/tag/TagManager.java
+++ b/iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/tag/TagManager.java
@@ -58,6 +58,8 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.Locale;
+
 
 import static java.util.stream.Collectors.toList;
 
@@ -242,9 +244,12 @@ private List<IMeasurementMNode<?>> getMatchedTimeseriesInIndex(TagFilter tagFilt
           continue;
         }
         String tagValue = entry.getKey();
-        if (tagValue.contains(tagFilter.getValue())) {
+        if (tagValue
+        .toLowerCase(Locale.ROOT)
+        .contains(tagFilter.getValue().toLowerCase(Locale.ROOT))) {
           allMatchedNodes.addAll(entry.getValue());
         }
+
       }
     } else {
       for (Map.Entry<String, Set<IMeasurementMNode<?>>> entry : value2Node.entrySet()) {