diff --git a/init.sql b/init.sql
index 8a283c5..12af5d1 100644
--- a/init.sql
+++ b/init.sql
@@ -20,6 +20,7 @@ create table if not exists training_data(
     constraint fk_training_id foreign key(training_id) references training(id) on delete cascade
 );
 create index if not exists idx_training_data_t on training_data(t);
+create index if not exists idx_training_data_training_id on training_data using hash(training_id);
 create index if not exists idx_training_data_geog on training_data using GIST(geog);
 
 create or replace view training_duration as