diff --git a/CHANGES.md b/CHANGES.md
index 09f1b6386..6ef99aeb2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -43,6 +43,7 @@ Release Notes.
 * Remove the duplicated tags to reduce the storage payload.
 * Add a new API to test log analysis language.
 * Harden the security of Groovy-based DSL, MAL and LAL.
+* Fix distinct in Service/Instance/Endpoint query is not working.
 
 #### UI
 
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Database.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Database.java
index 48a8dace3..b54c4529f 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Database.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Database.java
@@ -18,14 +18,13 @@
 
 package org.apache.skywalking.oap.server.core.query.type;
 
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
 
-/**
- *
- **/
 @Getter
 @Setter
+@EqualsAndHashCode
 public class Database {
     private String id;
     private String name;
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Endpoint.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Endpoint.java
index a6e4b4c2a..412bc3efa 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Endpoint.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Endpoint.java
@@ -18,11 +18,13 @@
 
 package org.apache.skywalking.oap.server.core.query.type;
 
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
 
 @Getter
 @Setter
+@EqualsAndHashCode
 public class Endpoint {
     private String id;
     private String name;
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Service.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Service.java
index b517f4b81..acdb2c357 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Service.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/Service.java
@@ -18,11 +18,13 @@
 
 package org.apache.skywalking.oap.server.core.query.type;
 
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
 
 @Getter
 @Setter
+@EqualsAndHashCode
 public class Service {
     private String id;
     private String name;
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/ServiceInstance.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/ServiceInstance.java
index 3caa648c9..47cefeae1 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/ServiceInstance.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/ServiceInstance.java
@@ -20,11 +20,13 @@ package org.apache.skywalking.oap.server.core.query.type;
 
 import java.util.ArrayList;
 import java.util.List;
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
 import org.apache.skywalking.oap.server.core.query.enumeration.Language;
 
 @Getter
+@EqualsAndHashCode
 public class ServiceInstance {
     @Setter
     private String id;