Use initially deferred foreign key constraint

On build.main_binary.

bin/migrations/builder_migrations.ml

@@ -122,5 +122,6 @@ let () =
         actions (module M20210625);
         actions (module M20210629);
         actions (module M20210630);
+        actions (module M20210701);
       ])
   |> Cmdliner.Term.exit

bin/migrations/m20210701.ml

@@ -0,0 +1,87 @@
+let new_version = 11L and old_version = 10L
+let identifier = "2021-07-01"
+let migrate_doc = "build.main_binary deferred foreign key constraint"
+let rollback_doc = "build.main_binary immediate foreign key constraint"
+
+let new_build =
+    Caqti_request.exec
+      Caqti_type.unit
+      {| CREATE TABLE new_build (
+           id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
+           uuid VARCHAR(36) NOT NULL UNIQUE,
+           start_d INTEGER NOT NULL,
+           start_ps INTEGER NOT NULL,
+           finish_d INTEGER NOT NULL,
+           finish_ps INTEGER NOT NULL,
+           result_kind TINYINT NOT NULL,
+           result_code INTEGER,
+           result_msg TEXT,
+           console BLOB NOT NULL,
+           script TEXT NOT NULL,
+           main_binary INTEGER,
+           user INTEGER NOT NULL,
+           job INTEGER NOT NULL,
+
+           FOREIGN KEY(main_binary) REFERENCES build_artifact(id) DEFERRABLE INITIALLY DEFERRED,
+           FOREIGN KEY(user) REFERENCES user(id),
+           FOREIGN KEY(job) REFERENCES job(id)
+         )
+      |}
+
+let old_build =
+    Caqti_request.exec
+      Caqti_type.unit
+      {| CREATE TABLE new_build (
+           id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
+           uuid VARCHAR(36) NOT NULL UNIQUE,
+           start_d INTEGER NOT NULL,
+           start_ps INTEGER NOT NULL,
+           finish_d INTEGER NOT NULL,
+           finish_ps INTEGER NOT NULL,
+           result_kind TINYINT NOT NULL,
+           result_code INTEGER,
+           result_msg TEXT,
+           console BLOB NOT NULL,
+           script TEXT NOT NULL,
+           main_binary INTEGER,
+           user INTEGER NOT NULL,
+           job INTEGER NOT NULL,
+
+           FOREIGN KEY(main_binary) REFERENCES build_artifact(id),
+           FOREIGN KEY(user) REFERENCES user(id),
+           FOREIGN KEY(job) REFERENCES job(id)
+         )
+      |}
+
+let copy_build =
+  Caqti_request.exec
+    Caqti_type.unit
+    "INSERT INTO new_build SELECT * from build"
+
+let drop_build =
+  Caqti_request.exec
+    Caqti_type.unit
+    "DROP TABLE build"
+
+let rename_build =
+  Caqti_request.exec
+    Caqti_type.unit
+    "ALTER TABLE new_build RENAME TO build"
+
+open Rresult.R.Infix
+
+let migrate _datadir (module Db : Caqti_blocking.CONNECTION) =
+  Grej.check_version ~user_version:old_version (module Db) >>= fun () ->
+  Db.exec new_build () >>= fun () ->
+  Db.exec copy_build () >>= fun () ->
+  Db.exec drop_build () >>= fun () ->
+  Db.exec rename_build () >>= fun () ->
+  Db.exec (Grej.set_version new_version) ()
+
+let rollback _datadir (module Db : Caqti_blocking.CONNECTION) =
+  Grej.check_version ~user_version:new_version (module Db) >>= fun () ->
+  Db.exec old_build () >>= fun () ->
+  Db.exec copy_build () >>= fun () ->
+  Db.exec drop_build () >>= fun () ->
+  Db.exec rename_build () >>= fun () ->
+  Db.exec (Grej.set_version old_version) ()

db/builder_db.ml

@@ -4,7 +4,7 @@ open Rep
 let application_id = 1234839235l
 
 (* Please update this when making changes! *)
-let current_version = 10L
+let current_version = 11L
 
 type id = Rep.id
 
@@ -328,7 +328,7 @@ module Build = struct
            user INTEGER NOT NULL,
            job INTEGER NOT NULL,
 
-           FOREIGN KEY(main_binary) REFERENCES build_artifact(id),
+           FOREIGN KEY(main_binary) REFERENCES build_artifact(id) DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY(user) REFERENCES user(id),
            FOREIGN KEY(job) REFERENCES job(id)
          )