Add titles and move insert_ids to class variable

This fixes the bug where the new ids are not saved

migration/titles.5.cr

@@ -0,0 +1,59 @@
+class CreateTitles < MG::Base
+  def up : String
+    <<-SQL
+    -- create titles
+    CREATE TABLE titles (
+      id TEXT NOT NULL,
+      path TEXT NOT NULL,
+      signature TEXT
+    );
+    CREATE UNIQUE INDEX titles_id_idx on titles (id);
+    CREATE UNIQUE INDEX titles_path_idx on titles (path);
+
+    -- migrate data from ids to titles
+    INSERT INTO titles
+    SELECT id, path, null
+    FROM ids
+    WHERE is_title = 1;
+
+    DELETE FROM ids
+    WHERE is_title = 1;
+
+    -- remove the is_title column from ids
+    ALTER TABLE ids RENAME TO tmp;
+
+    CREATE TABLE ids (
+      path TEXT NOT NULL,
+      id TEXT NOT NULL
+    );
+
+    INSERT INTO ids
+    SELECT path, id
+    FROM tmp;
+
+    DROP TABLE tmp;
+
+    -- recreate the indices
+    CREATE UNIQUE INDEX path_idx ON ids (path);
+    CREATE UNIQUE INDEX id_idx ON ids (id);
+    SQL
+  end
+
+  def down : String
+    <<-SQL
+    -- insert the is_title column
+    ALTER TABLE ids ADD COLUMN is_title INTEGER NOT NULL;
+
+    -- set is_title for all rows to 0
+    UPDATE ids SET column = 0;
+
+    -- migrate data from titles to ids
+    INSERT INTO ids
+    SELECT path, id, 1
+    FROM titles;
+
+    -- remove titles
+    DROP TABLE titles;
+    SQL
+  end
+end