Add position column in labels table

packages/db/migrations/0090.do.add_position_to_labels.sql

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+-- Type: DO
+-- Name: add_position_to_labels
+-- Description: Add position column to labels table
+
+BEGIN;
+
+ALTER TABLE omnivore.labels ADD COLUMN position INTEGER NOT NULL DEFAULT 0;
+
+WITH positions AS (
+    SELECT
+        id, row_number() OVER (PARTITION BY user_id ORDER BY name) as row_num
+    FROM
+        omnivore.labels
+) UPDATE
+      omnivore.labels
+  SET
+      position = positions.row_num
+  FROM
+      positions
+  WHERE
+      omnivore.labels.id = positions.id;
+
+ALTER TABLE omnivore.labels ADD constraint labels_position_user_id_unique UNIQUE(user_id, position);
+
+COMMIT;

packages/db/migrations/0090.undo.add_position_to_labels.sql

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+-- Type: UNDO
+-- Name: add_position_to_labels
+-- Description: Add position column to labels table
+
+BEGIN;
+
+ALTER TABLE omnivore.labels DROP COLUMN IF EXISTS position;
+
+COMMIT;