diff --git a/src/Oro/Bundle/DataGridBundle/Extension/Sorter/PostgresqlGridModifier.php b/src/Oro/Bundle/DataGridBundle/Extension/Sorter/PostgresqlGridModifier.php
index 611a00420eb..57ca266478e 100644
--- a/src/Oro/Bundle/DataGridBundle/Extension/Sorter/PostgresqlGridModifier.php
+++ b/src/Oro/Bundle/DataGridBundle/Extension/Sorter/PostgresqlGridModifier.php
@@ -89,7 +89,7 @@ public function visitDatasource(DatagridConfiguration $config, DatasourceInterfa
         if ($alias && $this->isAllowedAddingSorting($alias, $identifier, $queryBuilder)) {
             $field = $alias . '.' . $identifier;
             $orderBy = $queryBuilder->getDQLPart('orderBy');
-            if (!isset($orderBy[$field])) {
+            if (!$this->hasOrderByField($orderBy, $field)) {
                 if ($this->isDistinct($queryBuilder)) {
                     $this->ensureIdentifierSelected($queryBuilder, $field);
                 }
@@ -98,6 +98,23 @@ public function visitDatasource(DatagridConfiguration $config, DatasourceInterfa
         }
     }
 
+    /**
+     * Check field already exists in orders part
+     *
+     * @param array $orderBy
+     * @param string $field
+     * @return bool
+     */
+    protected function hasOrderByField($orderBy, $field)
+    {
+        foreach ($orderBy as $order) {
+            if (preg_match(sprintf('/(^|\s)%s\s/i', $field), $order)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     /**
      * @param DatagridConfiguration $config
      *
@@ -127,7 +144,7 @@ protected function isAllowedAddingSorting($alias, $identifier, QueryBuilder $que
 
             $selectPartsWithAggregation = array_filter($selectParts, function ($selectPart) use ($forbiddenFunctions) {
                 foreach ($forbiddenFunctions as $functionName) {
-                    if (false !== stripos($selectPart, $functionName)) {
+                    if (false !== stripos($selectPart, $functionName . '(')) {
                         return true;
                     }
                 }
diff --git a/src/Oro/Bundle/DataGridBundle/Tests/Unit/Extension/Sorter/PostgresqlGridModifierTest.php b/src/Oro/Bundle/DataGridBundle/Tests/Unit/Extension/Sorter/PostgresqlGridModifierTest.php
new file mode 100644
index 00000000000..800ac9a954b
--- /dev/null
+++ b/src/Oro/Bundle/DataGridBundle/Tests/Unit/Extension/Sorter/PostgresqlGridModifierTest.php
@@ -0,0 +1,133 @@
+<?php
+
+namespace Oro\Bundle\DataGridBundle\Tests\Unit\Extension\Sorter;
+
+use Doctrine\ORM\EntityManager;
+use Doctrine\ORM\Mapping\ClassMetadata;
+use Doctrine\ORM\QueryBuilder;
+use Doctrine\ORM\Query\Expr\OrderBy;
+
+use Oro\Bundle\DataGridBundle\Datagrid\Common\DatagridConfiguration;
+use Oro\Bundle\DataGridBundle\Datasource\Orm\OrmDatasource;
+use Oro\Bundle\DataGridBundle\Extension\Sorter\PostgresqlGridModifier;
+use Oro\Bundle\EntityBundle\ORM\EntityClassResolver;
+
+class PostgresqlGridModifierTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @var PostgresqlGridModifier
+     */
+    protected $extension;
+
+    protected $entityClassResolver;
+
+    public function setUp()
+    {
+        $this->entityClassResolver = $this->getMockBuilder(EntityClassResolver::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $this->extension = new PostgresqlGridModifier('pdo_pgsql', $this->entityClassResolver);
+    }
+
+    /**
+     * @dataProvider visitDatasourceDataProvider
+     */
+    public function testVisitDatasource($orderBy, $expected)
+    {
+        $em = $this->getMockBuilder(EntityManager::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $metadata = $this->getMockBuilder(ClassMetadata::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $em->expects(self::once())
+            ->method('getClassMetadata')
+            ->with('Test\Entity')
+            ->willReturn($metadata);
+
+        $metadata->expects(self::once())
+            ->method('getSingleIdentifierFieldName')
+            ->willReturn('id');
+
+        $qb = new QueryBuilder($em);
+        $qb->select('e.id')->from('Test\Entity', 'e');
+
+        if (!empty($orderBy)) {
+            $orderByExpr = new OrderBy();
+            foreach ($orderBy as $field => $des) {
+                $orderByExpr->add($field, $des);
+            }
+            $qb->addOrderBy($orderByExpr);
+        }
+
+        $datasource = $this->getMockBuilder(OrmDatasource::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $datasource->expects(self::once())
+            ->method('getQueryBuilder')
+            ->willReturn($qb);
+
+        $this->entityClassResolver->expects($this->any())
+            ->method('getEntityClass')
+            ->willReturn('Test\Entity');
+
+        $dataGridConfig = DatagridConfiguration::create([
+            'sorters' => [
+                'columns' => []
+            ],
+            'source'  => [
+                'type'    => 'orm',
+                'query'   => [
+                    'from' => [
+                        [
+                            'table' => 'Test\Entity',
+                            'alias' => 'e'
+                        ]
+                    ]
+                ]
+            ]
+        ]);
+
+        $this->extension->visitDatasource(
+            $dataGridConfig,
+            $datasource
+        );
+
+        self::assertEquals(
+            $expected,
+            $qb->getDQL()
+        );
+    }
+
+    /**
+     * @return array
+     */
+    public function visitDatasourceDataProvider()
+    {
+        return [
+            'OrderBy has only primary key field'     => [
+                ['e.id' => 'ASC'],
+                'SELECT e.id FROM Test\Entity e ORDER BY e.id ASC'
+            ],
+            'OrderBy has no primary key field'       => [
+                ['e.name' => 'ASC'],
+                'SELECT e.id FROM Test\Entity e ORDER BY e.name ASC, e.id ASC'
+            ],
+            'OrderBy has no fields'                  => [
+                [],
+                'SELECT e.id FROM Test\Entity e ORDER BY e.id ASC'
+            ],
+            'OrderBy has primary key field'          => [
+                ['e.name' => 'DESC', 'e.id' => 'DESC'],
+                'SELECT e.id FROM Test\Entity e ORDER BY e.name DESC, e.id DESC'
+            ],
+            'OrderBy has primary key field as first' => [
+                ['e.id' => 'DESC', 'e.name' => 'ASC'],
+                'SELECT e.id FROM Test\Entity e ORDER BY e.id DESC, e.name ASC'
+            ],
+        ];
+    }
+}