diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
index d4a96b3..0dd1dc6 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
@@ -70,7 +70,7 @@ protected function ensureIdentifiersLength($identifier) {
     $this->maxIdentifierLength = $this->connection->query("SHOW max_identifier_length")->fetchField();

     if (strlen($identifierName) > $this->maxIdentifierLength) {
-      $saveIdentifier = 'drupal_' . $this->hashBase64($identifierName) . '_' . $args[2];
+      $saveIdentifier = '"drupal_' . $this->hashBase64($identifierName) . '_' . $args[2] . '"';
     }
     else {
       $saveIdentifier = $identifierName;
@@ -211,11 +211,11 @@ protected function createTableSql($name, $table) {

     $sql_keys = array();
     if (isset($table['primary key']) && is_array($table['primary key'])) {
-      $sql_keys[] = 'CONSTRAINT "' . $this->ensureIdentifiersLength($name, '', 'pkey') . '" PRIMARY KEY (' . $this->createPrimaryKeySql($table['primary key']) . ')';
+      $sql_keys[] = 'CONSTRAINT ' . $this->ensureIdentifiersLength($name, '', 'pkey') . ' PRIMARY KEY (' . $this->createPrimaryKeySql($table['primary key']) . ')';
     }
     if (isset($table['unique keys']) && is_array($table['unique keys'])) {
       foreach ($table['unique keys'] as $key_name => $key) {
-        $sql_keys[] = 'CONSTRAINT "' . $this->ensureIdentifiersLength($name, $key_name, 'key') . '" UNIQUE (' . implode(', ', $key) . ')';
+        $sql_keys[] = 'CONSTRAINT ' . $this->ensureIdentifiersLength($name, $key_name, 'key') . ' UNIQUE (' . implode(', ', $key) . ')';
       }
     }

@@ -454,7 +454,7 @@ function renameTable($table, $new_name) {
         preg_match('/^' . preg_quote($old_full_name) . '__(.*)__' . preg_quote($index_type) . '/', $index->indexname, $matches);
         $index_name = $matches[1];
       }
-      $this->connection->query('ALTER INDEX "' . $index->indexname . '" RENAME TO "' . $this->ensureIdentifiersLength($new_name, $index_name, $index_type) . '"');
+      $this->connection->query('ALTER INDEX "' . $index->indexname . '" RENAME TO ' . $this->ensureIdentifiersLength($new_name, $index_name, $index_type) . '');
     }

     // Ensure the new table name does not include schema syntax.
@@ -549,6 +549,8 @@ public function fieldSetNoDefault($table, $field) {
   public function indexExists($table, $name) {
     // Details http://www.postgresql.org/docs/8.3/interactive/view-pg-indexes.html
     $index_name = $this->ensureIdentifiersLength($table, $name, 'idx');
+    // Remove leading and trailing quotes.
+    $index_name = substr($index_name, 1, -1);
     return (bool) $this->connection->query("SELECT 1 FROM pg_indexes WHERE indexname = '$index_name'")->fetchField();
   }

@@ -562,6 +564,8 @@ public function indexExists($table, $name) {
    */
   public function constraintExists($table, $name) {
     $constraint_name = $this->ensureIdentifiersLength($table, $name);
+    // Remove leading and trailing quotes.
+    $constraint_name = substr($constraint_name, 1, -1);
     return (bool) $this->connection->query("SELECT 1 FROM pg_constraint WHERE conname = '$constraint_name'")->fetchField();
   }

@@ -573,7 +577,7 @@ public function addPrimaryKey($table, $fields) {
       throw new SchemaObjectExistsException(t("Cannot add primary key to table @table: primary key already exists.", array('@table' => $table)));
     }

-    $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT "' . $this->ensureIdentifiersLength($table, '', 'pkey') . '" PRIMARY KEY (' . $this->createPrimaryKeySql($fields) . ')');
+    $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT ' . $this->ensureIdentifiersLength($table, '', 'pkey') . ' PRIMARY KEY (' . $this->createPrimaryKeySql($fields) . ')');
     $this->resetTableInformation($table);
   }

@@ -582,7 +586,7 @@ public function dropPrimaryKey($table) {
       return FALSE;
     }

-    $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT "' . $this->ensureIdentifiersLength($table, '', 'pkey') . '"');
+    $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT ' . $this->ensureIdentifiersLength($table, '', 'pkey'));
     $this->resetTableInformation($table);
     return TRUE;
   }
@@ -595,7 +599,7 @@ function addUniqueKey($table, $name, $fields) {
       throw new SchemaObjectExistsException(t("Cannot add unique key @name to table @table: unique key already exists.", array('@table' => $table, '@name' => $name)));
     }

-    $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT "' . $this->ensureIdentifiersLength($table, $name, 'key') . '" UNIQUE (' . implode(',', $fields) . ')');
+    $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT ' . $this->ensureIdentifiersLength($table, $name, 'key') . ' UNIQUE (' . implode(',', $fields) . ')');
     $this->resetTableInformation($table);
   }

@@ -604,7 +608,7 @@ public function dropUniqueKey($table, $name) {
       return FALSE;
     }

-    $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT "' . $this->ensureIdentifiersLength($table, $name, 'key') . '"');
+    $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT ' . $this->ensureIdentifiersLength($table, $name, 'key'));
     $this->resetTableInformation($table);
     return TRUE;
   }
@@ -735,7 +739,7 @@ public function changeField($table, $field, $field_new, $spec, $new_keys = array
   }

   protected function _createIndexSql($table, $name, $fields) {
-    $query = 'CREATE INDEX "' . $this->ensureIdentifiersLength($table, $name, 'idx') . '" ON {' . $table . '} (';
+    $query = 'CREATE INDEX ' . $this->ensureIdentifiersLength($table, $name, 'idx') . ' ON {' . $table . '} (';
     $query .= $this->_createKeySql($fields) . ')';
     return $query;
   }
diff --git a/core/modules/system/src/Tests/Entity/EntityDefinitionUpdateTest.php b/core/modules/system/src/Tests/Entity/EntityDefinitionUpdateTest.php
index 05d2a06..9937d3a 100644
--- a/core/modules/system/src/Tests/Entity/EntityDefinitionUpdateTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityDefinitionUpdateTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\system\Tests\Entity;

 use Drupal\Core\Database\DatabaseExceptionWrapper;
+use Drupal\Core\Database\IntegrityConstraintViolationException;
 use Drupal\Core\Entity\EntityStorageException;
 use Drupal\Core\Entity\EntityTypeEvents;
 use Drupal\Core\Entity\Exception\FieldStorageDefinitionUpdateForbiddenException;
@@ -359,14 +360,19 @@ public function testBundleFieldCreateDeleteWithExistingEntities() {
         ->execute();
       $this->fail($message);
     }
-    catch (DatabaseExceptionWrapper $e) {
-      // Now provide a value for the 'not null' column. This is expected to
-      // succeed.
-      $values['new_bundle_field_shape'] = $this->randomString();
-      $this->database->insert('entity_test_update__new_bundle_field')
-        ->fields($values)
-        ->execute();
-      $this->pass($message);
+    catch (\RuntimeException $e) {
+      if ($e instanceof DatabaseExceptionWrapper || $e instanceof IntegrityConstraintViolationException) {
+        // Now provide a value for the 'not null' column. This is expected to
+        // succeed.
+        $values['new_bundle_field_shape'] = $this->randomString();
+        $this->database->insert('entity_test_update__new_bundle_field')
+          ->fields($values)
+          ->execute();
+        $this->pass($message);
+      } else {
+        // Keep throwing it.
+        throw $e;
+      }
     }
   }