diff --git a/api/apps/kb_app.py b/api/apps/kb_app.py
index 249ac2d73..14caf7c22 100644
--- a/api/apps/kb_app.py
+++ b/api/apps/kb_app.py
@@ -107,6 +107,7 @@ def update():
                 settings.docStoreConn.update({"kb_id": kb.id}, {"pagerank_fea": req["pagerank"]},
                                          search.index_name(kb.tenant_id), kb.id)
             else:
+                # Elasticsearch requires pagerank_fea be non-zero!
                 settings.docStoreConn.update({"exist": "pagerank_fea"}, {"remove": "pagerank_fea"},
                                          search.index_name(kb.tenant_id), kb.id)
 
diff --git a/rag/utils/infinity_conn.py b/rag/utils/infinity_conn.py
index 2cbfede59..7c56a107a 100644
--- a/rag/utils/infinity_conn.py
+++ b/rag/utils/infinity_conn.py
@@ -46,13 +46,14 @@ def equivalent_condition_to_str(condition: dict) -> str|None:
             cond.append(f"{k}='{v}'")
         else:
             cond.append(f"{k}={str(v)}")
-    return " AND ".join(cond) if cond else None
+    return " AND ".join(cond) if cond else "1=1"
 
 
 def concat_dataframes(df_list: list[pl.DataFrame], selectFields: list[str]) -> pl.DataFrame:
     """
     Concatenate multiple dataframes into one.
     """
+    df_list = [df for df in df_list if not df.is_empty()]
     if df_list:
         return pl.concat(df_list)
     schema = dict()
@@ -246,8 +247,9 @@ class InfinityConnection(DocStoreConnection):
         db_instance = inf_conn.get_database(self.dbName)
         df_list = list()
         table_list = list()
-        if "id" not in selectFields:
-            selectFields.append("id")
+        for essential_field in ["id", "score()", "pagerank_fea"]:
+            if essential_field not in selectFields:
+                selectFields.append(essential_field)
 
         # Prepare expressions common to all tables
         filter_cond = None
@@ -331,10 +333,13 @@ class InfinityConnection(DocStoreConnection):
                 kb_res, extra_result = builder.option({"total_hits_count": True}).to_pl()
                 if extra_result:
                     total_hits_count += int(extra_result["total_hits_count"])
+                logger.debug(f"INFINITY search table: {str(table_name)}, result: {str(kb_res)}")
                 df_list.append(kb_res)
         self.connPool.release_conn(inf_conn)
         res = concat_dataframes(df_list, selectFields)
-        logger.debug(f"INFINITY search tables: {str(table_list)}, result: {str(res)}")
+        res = res.sort(pl.col("SCORE") + pl.col("pagerank_fea"), descending=True, maintain_order=True)
+        res = res.limit(limit)
+        logger.debug(f"INFINITY search final result: {str(res)}")
         return res, total_hits_count
 
     def get(
@@ -350,12 +355,10 @@ class InfinityConnection(DocStoreConnection):
             table_list.append(table_name)
             table_instance = db_instance.get_table(table_name)
             kb_res, _ = table_instance.output(["*"]).filter(f"id = '{chunkId}'").to_pl()
-            if len(kb_res) != 0 and kb_res.shape[0] > 0:
-                df_list.append(kb_res)
-
+            logger.debug(f"INFINITY get table: {str(table_list)}, result: {str(kb_res)}")
+            df_list.append(kb_res)
         self.connPool.release_conn(inf_conn)
         res = concat_dataframes(df_list, ["id"])
-        logger.debug(f"INFINITY get tables: {str(table_list)}, result: {str(res)}")
         res_fields = self.getFields(res, res.columns)
         return res_fields.get(chunkId, None)
 
@@ -421,8 +424,10 @@ class InfinityConnection(DocStoreConnection):
         db_instance = inf_conn.get_database(self.dbName)
         table_name = f"{indexName}_{knowledgebaseId}"
         table_instance = db_instance.get_table(table_name)
+        if "exist" in condition:
+            del condition["exist"]
         filter = equivalent_condition_to_str(condition)
-        for k, v in newValue.items():
+        for k, v in list(newValue.items()):
             if k.endswith("_kwd") and isinstance(v, list):
                 newValue[k] = " ".join(v)
             elif k == 'kb_id':
@@ -435,6 +440,9 @@ class InfinityConnection(DocStoreConnection):
             elif k in ["page_num_int", "top_int"]:
                 assert isinstance(v, list)
                 newValue[k] = "_".join(f"{num:08x}" for num in v)
+            elif k == "remove" and v in ["pagerank_fea"]:
+                del newValue[k]
+                newValue[v] = 0
         logger.debug(f"INFINITY update table {table_name}, filter {filter}, newValue {newValue}.")
         table_instance.update(filter, newValue)
         self.connPool.release_conn(inf_conn)