The distinct query should replicate the fields in order by clause and the order by clause itself from inner query

This fixes DDC-1958

lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryOutputWalker.php

@@ -15,6 +15,7 @@ namespace Doctrine\ORM\Tools\Pagination;
 
 use Doctrine\ORM\Query\SqlWalker;
 use Doctrine\ORM\Query\AST\SelectStatement;
+use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
 
 /**
  * Wrap the query in order to select root entity IDs for pagination
@@ -132,8 +133,44 @@ class LimitSubqueryOutputWalker extends SqlWalker
         }
 
         // Build the counter query
+        if ($this->platform instanceof PostgreSqlPlatform) {
+            //http://www.doctrine-project.org/jira/browse/DDC-1958
+
+            // For every order by, find out the SQL alias by inspecting the ResultSetMapping
+            $sqlOrderColumns = array();
+            $orderBy = array();
+            if (isset($AST->orderByClause)){
+                foreach ($AST->orderByClause->orderByItems as $item) {
+                    $possibleAliases = array_keys($this->rsm->fieldMappings, $item->expression->field);
+
+                    foreach ($possibleAliases as $alias) {
+                        if ($this->rsm->columnOwnerMap[$alias] == $item->expression->identificationVariable) {
+                            $sqlOrderColumns[] = $alias;
+                            $orderBy[] = $alias . ' ' . $item->type;
+                            break;
+                        }
+                    }
+                }
+                //remove identifier aliases
+                $sqlOrderColumns = array_diff($sqlOrderColumns, $sqlIdentifier);
+            }
+
+            //we don't need orderBy in inner query
+            //However at least on 5.4.6 I'm getting a segmentation fault and thus we don't clear it for now
+            /*$AST->orderByClause = null;
+            $sql = parent::walkSelectStatement($AST);*/
+
+            if (count($orderBy)) {
+                $sql = sprintf('SELECT DISTINCT %s FROM (%s) dctrn_result ORDER BY %s',
+                    implode(', ', array_merge($sqlIdentifier, $sqlOrderColumns)), $sql, implode(', ', $orderBy));
+            } else {
                 $sql = sprintf('SELECT DISTINCT %s FROM (%s) dctrn_result',
                     implode(', ', $sqlIdentifier), $sql);
+            }
+        } else {
+            $sql = sprintf('SELECT DISTINCT %s FROM (%s) dctrn_result',
+                implode(', ', $sqlIdentifier), $sql);
+        }
 
         // Apply the limit and offset
         $sql = $this->platform->modifyLimitQuery(

tests/Doctrine/Tests/ORM/Tools/Pagination/LimitSubqueryOutputWalkerTest.php

@@ -10,14 +10,42 @@ class LimitSubqueryOutputWalkerTest extends PaginationTestCase
     {
         $query = $this->entityManager->createQuery(
             'SELECT p, c, a FROM Doctrine\Tests\ORM\Tools\Pagination\MyBlogPost p JOIN p.category c JOIN p.author a');
+        $query->expireQueryCache(true);
         $limitQuery = clone $query;
         $limitQuery->setHint(Query::HINT_CUSTOM_OUTPUT_WALKER, 'Doctrine\ORM\Tools\Pagination\LimitSubqueryOutputWalker');
 
         $this->assertEquals(
-            "SELECT DISTINCT id0 FROM (SELECT m0_.id AS id0, c1_.id AS id1, a2_.id AS id2, a2_.name AS name3, m0_.author_id AS author_id4, m0_.category_id AS category_id5 FROM MyBlogPost m0_ INNER JOIN Category c1_ ON m0_.category_id = c1_.id INNER JOIN Author a2_ ON m0_.author_id = a2_.id) dctrn_result", $limitQuery->getSql()
+            "SELECT DISTINCT id0 FROM (SELECT m0_.id AS id0, m0_.title AS title1, c1_.id AS id2, a2_.id AS id3, a2_.name AS name4, m0_.author_id AS author_id5, m0_.category_id AS category_id6 FROM MyBlogPost m0_ INNER JOIN Category c1_ ON m0_.category_id = c1_.id INNER JOIN Author a2_ ON m0_.author_id = a2_.id) dctrn_result", $limitQuery->getSql()
         );
     }
 
+    public function testLimitSubqueryWithSortPg()
+    {
+        $odp = $this->entityManager->getConnection()->getDatabasePlatform();
+        $this->entityManager->getConnection()->setDatabasePlatform(new \Doctrine\DBAL\Platforms\PostgreSqlPlatform);
+
+        $query = $this->entityManager->createQuery(
+            'SELECT p, c, a FROM Doctrine\Tests\ORM\Tools\Pagination\MyBlogPost p JOIN p.category c JOIN p.author a ORDER BY p.title');
+        $limitQuery = clone $query;
+        $limitQuery->setHint(Query::HINT_CUSTOM_OUTPUT_WALKER, 'Doctrine\ORM\Tools\Pagination\LimitSubqueryOutputWalker');
+
+        $this->assertEquals(
+            "SELECT DISTINCT id0, title1 FROM (SELECT m0_.id AS id0, m0_.title AS title1, c1_.id AS id2, a2_.id AS id3, a2_.name AS name4, m0_.author_id AS author_id5, m0_.category_id AS category_id6 FROM MyBlogPost m0_ INNER JOIN Category c1_ ON m0_.category_id = c1_.id INNER JOIN Author a2_ ON m0_.author_id = a2_.id ORDER BY m0_.title ASC) dctrn_result ORDER BY title1 ASC", $limitQuery->getSql()
+        );
+
+        $this->entityManager->getConnection()->setDatabasePlatform($odp);
+    }
+
+    public function testLimitSubqueryPg()
+    {
+        $odp = $this->entityManager->getConnection()->getDatabasePlatform();
+        $this->entityManager->getConnection()->setDatabasePlatform(new \Doctrine\DBAL\Platforms\PostgreSqlPlatform);
+
+        $this->testLimitSubquery();
+
+        $this->entityManager->getConnection()->setDatabasePlatform($odp);
+    }
+
     public function testCountQuery_MixedResultsWithName()
     {
         $query = $this->entityManager->createQuery(

tests/Doctrine/Tests/ORM/Tools/Pagination/LimitSubqueryWalkerTest.php

@@ -21,6 +21,18 @@ class LimitSubqueryWalkerTest extends PaginationTestCase
         );
     }
 
+    public function testLimitSubqueryWithSort()
+    {
+        $query = $this->entityManager->createQuery(
+            'SELECT p, c, a FROM Doctrine\Tests\ORM\Tools\Pagination\MyBlogPost p JOIN p.category c JOIN p.author a ORDER BY p.title');
+        $limitQuery = clone $query;
+        $limitQuery->setHint(Query::HINT_CUSTOM_TREE_WALKERS, array('Doctrine\ORM\Tools\Pagination\LimitSubqueryWalker'));
+
+        $this->assertEquals(
+            "SELECT DISTINCT m0_.id AS id0, m0_.title AS title1 FROM MyBlogPost m0_ INNER JOIN Category c1_ ON m0_.category_id = c1_.id INNER JOIN Author a2_ ON m0_.author_id = a2_.id ORDER BY m0_.title ASC", $limitQuery->getSql()
+        );
+    }
+
     public function testCountQuery_MixedResultsWithName()
     {
         $query = $this->entityManager->createQuery(

tests/Doctrine/Tests/ORM/Tools/Pagination/PaginationTestCase.php

@@ -31,6 +31,8 @@ class MyBlogPost
      * @ManyToOne(targetEntity="Category")
      */
     public $category;
+    /** @column(type="string") */
+    public $title;
 }
 
 /**