diff --git a/src/server/object_services/schemas/data_chunk_indexes.js b/src/server/object_services/schemas/data_chunk_indexes.js
index 9bb89ed335..235b8645df 100644
--- a/src/server/object_services/schemas/data_chunk_indexes.js
+++ b/src/server/object_services/schemas/data_chunk_indexes.js
@@ -17,6 +17,8 @@ module.exports = [{
     {
         fields: {
             dedup_key: 1,
+            system: 1,
+            bucket: 1
         },
         options: {
             unique: false,
diff --git a/src/upgrade/upgrade_scripts/5.21.0/remove_datachunks_index.js b/src/upgrade/upgrade_scripts/5.21.0/remove_datachunks_index.js
new file mode 100644
index 0000000000..1caa5e3631
--- /dev/null
+++ b/src/upgrade/upgrade_scripts/5.21.0/remove_datachunks_index.js
@@ -0,0 +1,23 @@
+/* Copyright (C) 2025 NooBaa */
+"use strict";
+
+async function run({ dbg, db_client }) {
+  /* After the index is dropped, a new composite index (system, bucket, dedup_key) 
+    will be created during bootstrap */
+  const indexName = 'idx_btree_datachunks_dedup_key';
+
+  try {
+    const pool = db_client.instance().get_pool();
+    await pool.query(`DROP INDEX IF EXISTS ${indexName};`);
+
+    dbg.log0("Executed upgrade script for dropping index ", indexName);
+  } catch (err) {
+    dbg.error('An error ocurred in the upgrade process:', err);
+    throw err;
+  }
+}
+
+module.exports = {
+  run,
+  description: 'Delete the "idx_btree_datachunks_dedup_key" index'
+};