Issue #2370593 by poker10, daffie, joseph.olstad, nathanweeks,...

Issue #2370593 by poker10, daffie, joseph.olstad, nathanweeks, Sivaji_Ganesh_Jojodae, bzrudi71, webchick, mcdruid, Fabianx: Database::tableExists optimization for PostgreSQL

includes/database/pgsql/schema.inc

@@ -414,6 +414,17 @@ protected function _createKeySql($fields) {
     return implode(', ', $return);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function tableExists($table) {
+    // In PostgreSQL "unquoted names are always folded to lower case."
+    // @see DatabaseSchema_pgsql::buildTableNameCondition().
+    $prefixInfo = $this->getPrefixInfo(strtolower($table), TRUE);
+
+    return (bool) $this->connection->query("SELECT 1 FROM pg_tables WHERE schemaname = :schema AND tablename = :table", array(':schema' => $prefixInfo['schema'], ':table' => $prefixInfo['table']))->fetchField();
+  }
+
   function renameTable($table, $new_name) {
     if (!$this->tableExists($table)) {
       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));