From 15a534909f53af7db1e15d858ac71ff6e7708966 Mon Sep 17 00:00:00 2001
From: dive2tech <phivesyard@gmail.com>
Date: Wed, 28 Jan 2026 01:38:03 -0500
Subject: [PATCH] fix: avoid ZeroDivisionError when fulltext column weights sum
 to zero (#12856)

### What problem does this PR solve?

When all fulltext_search_columns use explicit weight 0 (e.g. "col^0"),
weight_sum is 0 and dividing by it raises ZeroDivisionError. Use equal
weights 1/n when weight_sum <= 0 and n > 0; otherwise normalize as
before.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] New Feature (non-breaking change which adds functionality)
- [x] Documentation Update
- [x] Refactoring
---
 rag/utils/ob_conn.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/rag/utils/ob_conn.py b/rag/utils/ob_conn.py
index 78a77e9c9..8a3ef49d4 100644
--- a/rag/utils/ob_conn.py
+++ b/rag/utils/ob_conn.py
@@ -928,8 +928,14 @@ class OBConnection(DocStoreConnection):
 
                 # adjust the weight to 0~1
                 weight_sum = sum(fulltext_search_weight.values())
-                for column_name in fulltext_search_weight.keys():
-                    fulltext_search_weight[column_name] = fulltext_search_weight[column_name] / weight_sum
+                n = len(fulltext_search_weight)
+                if weight_sum <= 0 and n > 0:
+                    # All weights are 0 (e.g. "col^0"); use equal weights to avoid ZeroDivisionError
+                    for column_name in fulltext_search_weight:
+                        fulltext_search_weight[column_name] = 1.0 / n
+                else:
+                    for column_name in fulltext_search_weight:
+                        fulltext_search_weight[column_name] = fulltext_search_weight[column_name] / weight_sum
 
             elif isinstance(m, MatchDenseExpr):
                 assert m.embedding_data_type == "float", f"embedding data type '{m.embedding_data_type}' is not float."