Add new derivation_output_details_set_id column to the builds table

As this will hopefully provide a faster way of associating derivations with
builds.

sqitch/deploy/builds_add_derivation_output_details_set_id.sql

@@ -0,0 +1,22 @@
+-- Deploy guix-data-service:builds_add_derivation_output_details_set_id to pg
+
+BEGIN;
+
+ALTER TABLE builds
+  ADD COLUMN derivation_output_details_set_id integer
+  NULL
+  DEFAULT NULL
+  REFERENCES derivation_output_details_sets (id);
+
+UPDATE builds SET derivation_output_details_set_id = (
+  SELECT derivations_by_output_details_set.derivation_output_details_set_id
+  FROM derivations_by_output_details_set
+  INNER JOIN derivations
+    ON derivations.file_name = builds.derivation_file_name
+  WHERE derivations_by_output_details_set.derivation_id = derivations.id
+);
+
+CREATE INDEX builds_derivation_output_details_set_id ON
+  builds (derivation_output_details_set_id);
+
+COMMIT;