SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

#0 /v1/www/magento.mainacad.com/lib/Zend/Db/Adapter/Pdo/Mysql.php(109): Zend_Db_Adapter_Pdo_Abstract->_connect()
#1 /v1/www/magento.mainacad.com/lib/Varien/Db/Adapter/Pdo/Mysql.php(320): Zend_Db_Adapter_Pdo_Mysql->_connect()
#2 /v1/www/magento.mainacad.com/lib/Zend/Db/Adapter/Abstract.php(460): Varien_Db_Adapter_Pdo_Mysql->_connect()
#3 /v1/www/magento.mainacad.com/lib/Zend/Db/Adapter/Pdo/Abstract.php(238): Zend_Db_Adapter_Abstract->query('SET NAMES utf8', Array)
#4 /v1/www/magento.mainacad.com/lib/Varien/Db/Adapter/Pdo/Mysql.php(428): Zend_Db_Adapter_Pdo_Abstract->query('SET NAMES utf8', Array)
#5 /v1/www/magento.mainacad.com/app/code/core/Mage/Core/Model/Resource/Type/Db/Pdo/Mysql.php(45): Varien_Db_Adapter_Pdo_Mysql->query('SET NAMES utf8')
#6 /v1/www/magento.mainacad.com/app/code/community/Mgt/DeveloperToolbar/Model/Resource.php(46): Mage_Core_Model_Resource_Type_Db_Pdo_Mysql->getConnection(Object(Mage_Core_Model_Config_Element))
#7 /v1/www/magento.mainacad.com/app/code/core/Mage/Core/Model/Resource/Setup.php(141): Mgt_DeveloperToolbar_Model_Resource->getConnection('core_setup')
#8 /v1/www/magento.mainacad.com/app/code/core/Mage/Core/Model/Resource/Setup.php(234): Mage_Core_Model_Resource_Setup->__construct('core_setup')
#9 /v1/www/magento.mainacad.com/app/code/core/Mage/Core/Model/App.php(417): Mage_Core_Model_Resource_Setup::applyAllUpdates()
#10 /v1/www/magento.mainacad.com/app/code/core/Mage/Core/Model/App.php(343): Mage_Core_Model_App->_initModules()
#11 /v1/www/magento.mainacad.com/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#12 /v1/www/magento.mainacad.com/index.php(88): Mage::run('', 'store')
#13 {main}