diff --git a/aggregator-service/db.py b/aggregator-service/db.py
index a697426..cf65eab 100644
--- a/aggregator-service/db.py
+++ b/aggregator-service/db.py
@@ -81,6 +81,11 @@ async def close_pool() -> None:
 -- BTREE index for filtering by status
 CREATE INDEX IF NOT EXISTS idx_jobs_status
     ON jobs (status);
+    
+-- Prevent duplicate job URLs by enforcing uniqueness
+CREATE UNIQUE INDEX IF NOT EXISTS idx_jobs_url_unique
+ON jobs(url)
+WHERE url IS NOT NULL;    
 """