From 8718f37a3aabba7d84298c6b2b8d68b2182af158 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Westk=C3=A4mper?= <timo.westkamper@gmail.com>
Date: Sat, 7 Mar 2015 00:19:01 +0200
Subject: [PATCH] Optimize exists queries

---
 .../main/java/com/querydsl/jpa/EclipseLinkTemplates.java   | 6 ------
 .../src/main/java/com/querydsl/jpa/HQLTemplates.java       | 6 ------
 .../src/main/java/com/querydsl/jpa/JPAQueryBase.java       | 7 +------
 .../src/main/java/com/querydsl/jpa/JPQLTemplates.java      | 4 ----
 .../src/test/java/com/querydsl/jpa/AbstractJPATest.java    | 1 +
 5 files changed, 2 insertions(+), 22 deletions(-)

diff --git a/querydsl-jpa/src/main/java/com/querydsl/jpa/EclipseLinkTemplates.java b/querydsl-jpa/src/main/java/com/querydsl/jpa/EclipseLinkTemplates.java
index a14924eae..ff32d63c6 100644
--- a/querydsl-jpa/src/main/java/com/querydsl/jpa/EclipseLinkTemplates.java
+++ b/querydsl-jpa/src/main/java/com/querydsl/jpa/EclipseLinkTemplates.java
@@ -95,10 +95,4 @@ public class EclipseLinkTemplates extends JPQLTemplates {
         return false;
     }
 
-    @Override
-    public boolean isSelect1Supported() {
-        return true;
-    }
-
-
 }
diff --git a/querydsl-jpa/src/main/java/com/querydsl/jpa/HQLTemplates.java b/querydsl-jpa/src/main/java/com/querydsl/jpa/HQLTemplates.java
index 32ba444c8..5f17a9ae7 100644
--- a/querydsl-jpa/src/main/java/com/querydsl/jpa/HQLTemplates.java
+++ b/querydsl-jpa/src/main/java/com/querydsl/jpa/HQLTemplates.java
@@ -116,12 +116,6 @@ public class HQLTemplates extends JPQLTemplates {
         return "1";
     }
 
-    @Override
-    public boolean isSelect1Supported() {
-        // TODO return true, when JPQLTemplates becomes standard
-        return false;
-    }
-
     @Override
     public boolean isEnumInPathSupported() {
         // related : http://opensource.atlassian.com/projects/hibernate/browse/HHH-5159
diff --git a/querydsl-jpa/src/main/java/com/querydsl/jpa/JPAQueryBase.java b/querydsl-jpa/src/main/java/com/querydsl/jpa/JPAQueryBase.java
index f51c60e6f..6ae03f190 100644
--- a/querydsl-jpa/src/main/java/com/querydsl/jpa/JPAQueryBase.java
+++ b/querydsl-jpa/src/main/java/com/querydsl/jpa/JPAQueryBase.java
@@ -64,12 +64,7 @@ public abstract class JPAQueryBase<Q extends JPAQueryBase<Q>> extends Projectabl
 
     @Override
     public boolean exists() {
-        if (templates.isSelect1Supported()) {
-            return singleResult(NumberTemplate.ONE) != null;
-        } else {            
-            EntityPath<?> entityPath = (EntityPath<?>) queryMixin.getMetadata().getJoins().get(0).getTarget();
-            return !limit(1).list(entityPath).isEmpty();
-        }                
+        return singleResult(NumberTemplate.ONE) != null;
     }
 
     public Q fetch() {
diff --git a/querydsl-jpa/src/main/java/com/querydsl/jpa/JPQLTemplates.java b/querydsl-jpa/src/main/java/com/querydsl/jpa/JPQLTemplates.java
index c89fa89d6..283737e4e 100644
--- a/querydsl-jpa/src/main/java/com/querydsl/jpa/JPQLTemplates.java
+++ b/querydsl-jpa/src/main/java/com/querydsl/jpa/JPQLTemplates.java
@@ -158,10 +158,6 @@ public class JPQLTemplates extends Templates {
         return true;
     }
 
-    public boolean isSelect1Supported() {
-        return false;
-    }
-
     @Nullable
     public String getExistsProjection() {
         return null;
diff --git a/querydsl-jpa/src/test/java/com/querydsl/jpa/AbstractJPATest.java b/querydsl-jpa/src/test/java/com/querydsl/jpa/AbstractJPATest.java
index 19f7cfb99..252511639 100644
--- a/querydsl-jpa/src/test/java/com/querydsl/jpa/AbstractJPATest.java
+++ b/querydsl-jpa/src/test/java/com/querydsl/jpa/AbstractJPATest.java
@@ -621,6 +621,7 @@ public abstract class AbstractJPATest {
     @Test
     public void Exists() {
         assertTrue(query().from(cat).where(cat.kittens.any().name.eq("Ruth123")).exists());
+        assertFalse(query().from(cat).where(cat.kittens.any().name.eq("Ruth321")).exists());
     }
 
     @Test