diff --git a/htdocs/install/mysql/tables/llx_ticket-ticket.key.sql b/htdocs/install/mysql/tables/llx_ticket-ticket.key.sql
index d4805d8a788..858f7c7eec5 100644
--- a/htdocs/install/mysql/tables/llx_ticket-ticket.key.sql
+++ b/htdocs/install/mysql/tables/llx_ticket-ticket.key.sql
@@ -21,3 +21,8 @@ ALTER TABLE llx_ticket ADD INDEX idx_ticket_fk_soc (fk_soc);
 ALTER TABLE llx_ticket ADD INDEX idx_ticket_fk_user_assign (fk_user_assign);
 ALTER TABLE llx_ticket ADD INDEX idx_ticket_fk_project (fk_project);
 ALTER TABLE llx_ticket ADD INDEX idx_ticket_fk_statut (fk_statut);
+
+-- Idea for better perf to get last num of ticket on large databases
+--ALTER TABLE llx_ticket ADD COLUMN calculated_numrefonly INTEGER AS (CASE SUBSTRING(ref FROM 1 FOR 2) WHEN 'TS' THEN CAST(SUBSTRING(ref FROM 8) AS SIGNED) ELSE 0 END) PERSISTENT;
+--ALTER TABLE llx_ticket ADD INDEX idx_calculated_numrefonly (calculated_numrefonly);
+--Then, the numering module can use the column calculated_numrefonly to get the max with SELECT MAX(calculated_numrefonly) FROM llx_ticket