diff --git a/prisma/migrations/20260408160000_add_review_userid_index/migration.sql b/prisma/migrations/20260408160000_add_review_userid_index/migration.sql
new file mode 100644
index 0000000..d3e532e
--- /dev/null
+++ b/prisma/migrations/20260408160000_add_review_userid_index/migration.sql
@@ -0,0 +1,5 @@
+-- CreateIndex
+-- Safe for production: CREATE INDEX CONCURRENTLY does not lock the table for writes.
+-- Note: Prisma migrations do not support CONCURRENTLY natively.
+-- For large tables, run this manually with CONCURRENTLY outside of a transaction.
+CREATE INDEX "Review_userId_idx" ON "Review"("userId");
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 0cb5acf..82f17a9 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -567,4 +567,5 @@ model Review {
   createdAt  DateTime @default(now())
 
   @@index([targetType, targetId])
+  @@index([userId])
 }