author_stats: add index on followers_count

src/db/migrations/035_author_stats_followers_index.ts

@@ -0,0 +1,17 @@
+import { Kysely } from 'kysely';
+
+export async function up(db: Kysely<any>): Promise<void> {
+  await db.schema
+    .createIndex('author_stats_followers_count_idx')
+    .ifNotExists()
+    .on('author_stats')
+    .column('followers_count desc')
+    .execute();
+
+  // This index should have never been added, because pubkey is the primary key.
+  await db.schema.dropIndex('idx_author_stats_pubkey').ifExists().execute();
+}
+
+export async function down(db: Kysely<any>): Promise<void> {
+  await db.schema.dropIndex('author_stats_followers_count_idx').ifExists().execute();
+}