diff --git a/migrations/20210118163847_fix_unique_index.sql b/migrations/20210118163847_fix_unique_index.sql
new file mode 100644
index 000000000..d61819f07
--- /dev/null
+++ b/migrations/20210118163847_fix_unique_index.sql
@@ -0,0 +1,15 @@
+-- +up
+-- +begin
+ALTER TABLE `trades` DROP INDEX `id`;
+-- +end
+-- +begin
+ALTER TABLE `trades` ADD UNIQUE INDEX `id` (`exchange`,`symbol`, `side`, `id`);
+-- +end
+
+-- +down
+-- +begin
+ALTER TABLE `trades` DROP INDEX `id`;
+-- +end
+-- +begin
+ALTER TABLE `trades` ADD UNIQUE INDEX `id` (`id`);
+-- +end
diff --git a/pkg/migrations/20210118163847_fix_unique_index.go b/pkg/migrations/20210118163847_fix_unique_index.go
new file mode 100644
index 000000000..bc00f7a93
--- /dev/null
+++ b/pkg/migrations/20210118163847_fix_unique_index.go
@@ -0,0 +1,43 @@
+package migrations
+
+import (
+	"context"
+
+	"github.com/c9s/rockhopper"
+)
+
+func init() {
+	rockhopper.AddMigration(upFixUniqueIndex, downFixUniqueIndex)
+}
+
+func upFixUniqueIndex(ctx context.Context, tx rockhopper.SQLExecutor) (err error) {
+	// This code is executed when the migration is applied.
+
+	_, err = tx.ExecContext(ctx, "ALTER TABLE `trades` DROP INDEX `id`;")
+	if err != nil {
+		return err
+	}
+
+	_, err = tx.ExecContext(ctx, "ALTER TABLE `trades` ADD INDEX UNIQUE `id` ON (`exchange`,`symbol`, `side`, `id`);")
+	if err != nil {
+		return err
+	}
+
+	return err
+}
+
+func downFixUniqueIndex(ctx context.Context, tx rockhopper.SQLExecutor) (err error) {
+	// This code is executed when the migration is rolled back.
+
+	_, err = tx.ExecContext(ctx, "ALTER TABLE `trades` DROP INDEX `id`;")
+	if err != nil {
+		return err
+	}
+
+	_, err = tx.ExecContext(ctx, "ALTER TABLE `trades` ADD INDEX UNIQUE `id` ON (`id`);")
+	if err != nil {
+		return err
+	}
+
+	return err
+}