Migration to remove duplicate users and add table constraints

app/src/db/migrations/20240828000000_008-user-id-constraint.ts

@@ -0,0 +1,36 @@
+/* eslint-disable max-len */
+import type { Knex } from 'knex';
+
+export async function up(knex: Knex): Promise<void> {
+  return (
+    Promise.resolve()
+      // Drop public schema functions
+      .then(() =>
+        knex.raw(`DELETE FROM "public"."user" AS u
+        WHERE u."userId" IN (
+          SELECT DISTINCT ON ("public"."user"."identityId") "public"."user"."userId"
+          FROM "public"."user"
+          WHERE (
+            SELECT count(*)
+            FROM "public"."user" AS user2
+            WHERE user2."identityId" = "public"."user"."identityId") > 1
+          ORDER BY "public"."user"."identityId", "public"."user"."createdAt" DESC
+        )`)
+      )
+
+      // prevent further duplicate users - add unique index over columns identityId and idp in user table
+      .then(() =>
+        knex.schema.alterTable('user', (table) => {
+          table.unique(['identityId', 'idp']);
+        })
+      )
+  );
+}
+
+export async function down(knex: Knex): Promise<void> {
+  return Promise.resolve().then(() =>
+    knex.schema.alterTable('user', (table) => {
+      table.dropUnique(['identityId', 'idp']);
+    })
+  );
+}