Add indexes on Builds id foreign keys.

This considerably speeds up cascade deleting.

* src/sql/upgrade-9.sql: New file.
* Makefile.am (dist_sql_DATA): Add it.
* src/schema.sql (Jobs_build, BuildProducts_build, Notifications_build): New
indexes.

Makefile.am

@@ -94,7 +94,9 @@ dist_sql_DATA = 				\
   src/sql/upgrade-4.sql				\
   src/sql/upgrade-5.sql				\
   src/sql/upgrade-6.sql				\
-  src/sql/upgrade-7.sql
+  src/sql/upgrade-7.sql				\
+  src/sql/upgrade-8.sql				\
+  src/sql/upgrade-9.sql
 
 dist_css_DATA =					\
   src/static/css/choices.min.css		\

src/schema.sql

@@ -133,10 +133,15 @@ CREATE INDEX Builds_weather_evaluation ON Builds (weather, evaluation);
 
 CREATE INDEX Jobs_name ON Jobs (name);
 CREATE INDEX Jobs_system_status ON Jobs (system, status);
+CREATE INDEX Jobs_build ON Jobs (build); --speeds up delete cascade.
 
 CREATE INDEX Evaluations_status_index ON Evaluations (id, status);
 CREATE INDEX Evaluations_specification_index ON Evaluations (specification, id DESC);
 
 CREATE INDEX Outputs_derivation_index ON Outputs (derivation);
 
+CREATE INDEX BuildProducts_build ON BuildProducts(build); --speeds up delete cascade.
+
+CREATE INDEX Notifications_build ON Notifications(build); --speeds up delete cascade.
+
 COMMIT;

src/sql/upgrade-9.sql

+BEGIN TRANSACTION;
+
+CREATE INDEX Jobs_build ON Jobs (build); --speeds up delete cascade.
+CREATE INDEX BuildProducts_build ON BuildProducts(build); --speeds up delete cascade.
+CREATE INDEX Notifications_build ON Notifications(build); --speeds up delete cascade.
+
+COMMIT;