Disable database triggers during import

- This allows `updated_at` field values to be loaded during import.
  Before this change, `updated_at` was set to when the import ran,
  overwriting the values being loaded.
- Also, the import completes in about one fifth the time
  (on my slow MacBook Air).

Author: bruceadams

src/tasks/dump_db/dump-import.sql.hbs

@@ -1,3 +1,10 @@
+BEGIN;
+    -- Disable triggers on each table.
+{{~#each tables}}
+    ALTER TABLE "{{this.name}}" DISABLE TRIGGER ALL;
+{{~/each}}
+COMMIT;
+
 BEGIN;
     -- Set defaults for non-nullable columns not included in the dump.
 {{~#each tables as |table|}}
@@ -23,3 +30,10 @@ BEGIN;
 {{~/each}}
 {{~/each}}
 COMMIT;
+
+BEGIN;
+    -- Reenable triggers on each table.
+{{~#each tables}}
+    ALTER TABLE "{{this.name}}" ENABLE TRIGGER ALL;
+{{~/each}}
+COMMIT;