diff --git a/init.sql b/init.sql
index 9a525df..cd8394e 100644
--- a/init.sql
+++ b/init.sql
@@ -20,4 +20,29 @@ 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_geog on training_data using GIST(geog);
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+create index if not exists idx_training_data_geog on training_data using GIST(geog);
+
+create or replace view training_duration as
+(select td_start.id as id,
+	td_start.t as start_time,
+	td_end.t as end_time,
+	date_trunc('second', (td_end.t - td_start.t)) as duration
+from (select td_row_n.t, td_row_n.id
+		from (select *,
+				row_number() over (partition by td.training_id order by td.t asc) as row_n
+			from training_data td join training t on (t.id = td.training_id)
+		order by td.t asc) as td_row_n
+	where td_row_n.row_n = 1
+	order by td_row_n.t asc) td_start
+	
+	join
+	
+	(select td_row_n.t, td_row_n.id
+		from (select *,
+				row_number() over (partition by td.training_id order by td.t desc) as row_n
+			from training_data td join training t on (t.id = td.training_id)
+		order by td.t asc) as td_row_n
+	where td_row_n.row_n = 1) td_end
+
+	on (td_start.id = td_end.id)
+);
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