diff --git a/recent_blocks_database.py b/recent_blocks_database.py
index 9b93481..cf83291 100644
--- a/recent_blocks_database.py
+++ b/recent_blocks_database.py
@@ -65,6 +65,7 @@ def run_query():
                 total_cu_used,
                 total_cu_requested
             FROM banking_stage_results.blocks
+            -- this critera uses index idx_blocks_slot_errors
             WHERE banking_stage_errors > 0
             ORDER BY slot DESC
             LIMIT 30