Error establishing a database connection

Hello. Sometimes a “Error establishing a database connection” error occurs for a long time. I have reviewed the error.log file. This plugin is giving a always error. Can you fix these errors? thanks

error.log

require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/tema/single.php'), the_content, apply_filters('the_content'), WP_Hook->apply_filters, C_NextGen_Shortcode_Manager->parse_content, C_NextGen_Shortcode_Manager->execute_found_shortcode, M_Gallery_Display->display_images, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Renderer->display_images, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_NextGen_Basic_Album_Routes->render, Mixin->call_parent, ExtensibleObject->call_method, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Renderer->render, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_NextGen_Basic_Gallery_Controller->index_action, Mixin->call_parent, ExtensibleObject->call_method, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_NextGen_Basic_Thumbnails_Controller->index_action, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Queries->get_entity_count, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_I18N_Displayed_Gallery_Translation->_get_image_entities, Mixin->call_parent, ExtensibleObject->call_method, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Queries->_get_image_entities, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, C_CustomTable_DataMapper_Driver_Mixin->run_query taraf?ndan olu?turulan SELECT DISTINCT pid , GROUP_CONCAT(CONCAT_WS('@@', meta_key, meta_value)) AS 'extras' FROMwp_ngg_picturesLEFT OUTER JOINwp_postmetaONwp_postmeta.post_id=extras_post_idWHERE (exclude= 0) AND (galleryidIN (930)) GROUP BY wp_ngg_pictures.pid ORDER BYsortorderASC sorgusu i?in WordPress veritaban? hatas? Out of resources when opening file '/tmp/#sql_f2ccc_0.MAI' (Errcode: 24 "Too many open files")

require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/tema/single.php'), the_content, apply_filters('the_content'), WP_Hook->apply_filters, C_NextGen_Shortcode_Manager->parse_content, C_NextGen_Shortcode_Manager->execute_found_shortcode, M_Gallery_Display->display_images, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Renderer->display_images, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_NextGen_Basic_Album_Routes->render, Mixin->call_parent, ExtensibleObject->call_method, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Renderer->render, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_NextGen_Basic_Gallery_Controller->index_action, Mixin->call_parent, ExtensibleObject->call_method, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_NextGen_Basic_Thumbnails_Controller->index_action, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Queries->get_included_entities, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Queries->get_entities, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, A_I18N_Displayed_Gallery_Translation->_get_image_entities, Mixin->call_parent, ExtensibleObject->call_method, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, Mixin_Displayed_Gallery_Queries->_get_image_entities, ExtensibleObject->__call, ExtensibleObject->_exec_cached_method, ReflectionMethod->invokeArgs, C_CustomTable_DataMapper_Driver_Mixin->run_query taraf?ndan olu?turulan SELECT DISTINCT wp_ngg_pictures.* , GROUP_CONCAT(CONCAT_WS('@@', meta_key, meta_value)) AS 'extras' FROMwp_ngg_picturesLEFT OUTER JOINwp_postmetaONwp_postmeta.post_id=extras_post_idWHERE (exclude= 0) AND (galleryidIN (930)) GROUP BY wp_ngg_pictures.pid ORDER BYsortorderASC LIMIT 24 sorgusu i?in WordPress veritaban? hatas? Out of resources when opening file '/tmp/#sql_f2ccc_0.MAI' (Errcode: 24 "Too many open files")