diff --git a/packages/uni-info-watcher/src/entity/Event.ts b/packages/uni-info-watcher/src/entity/Event.ts
index a854c405..8bb47f6f 100644
--- a/packages/uni-info-watcher/src/entity/Event.ts
+++ b/packages/uni-info-watcher/src/entity/Event.ts
@@ -7,7 +7,7 @@ import { BlockProgress } from './BlockProgress';
 
 @Entity()
 // Index to query events by block and event index.
-@Index(['block', 'index'])
+@Index(['block', 'index'], { unique: true })
 export class Event {
   @PrimaryGeneratedColumn()
   id!: number;
diff --git a/packages/uni-watcher/src/entity/Event.ts b/packages/uni-watcher/src/entity/Event.ts
index 9a2689ad..d2692cc5 100644
--- a/packages/uni-watcher/src/entity/Event.ts
+++ b/packages/uni-watcher/src/entity/Event.ts
@@ -9,7 +9,7 @@ export const UNKNOWN_EVENT_NAME = '__unknown__';
 
 @Entity()
 // Index to query events by block and event index.
-@Index(['block', 'index'])
+@Index(['block', 'index'], { unique: true })
 export class Event {
   @PrimaryGeneratedColumn()
   id!: number;