diff --git a/models/xbus_emitter_job.py b/models/xbus_emitter_job.py
index f5b3de757af178cb35f7f82800fc8de200a37584_bW9kZWxzL3hidXNfZW1pdHRlcl9qb2IucHk=..6e17210958b7832aa943ef41c0fcffb55fdb97ab_bW9kZWxzL3hidXNfZW1pdHRlcl9qb2IucHk= 100644
--- a/models/xbus_emitter_job.py
+++ b/models/xbus_emitter_job.py
@@ -111,6 +111,7 @@
         string="Envelope ID",
         help="The ID of the envelope that was forged by xbus-odoo and sent "
         "into the bus",
+        index=True,  # WHERE queries in xbus-odoo's emitter on this column.
     )
 
     process_id = fields.Char(