MediaWiki internal error.

Original exception: exception 'DBQueryError' with message 'A database error has occurred
Query: SELECT old_text,old_flags FROM `text` WHERE old_id = '22008' LIMIT 1
Function: Revision::loadText
Error: 2002 Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) (localhost)
' in /usr/share/mediawiki1.7/includes/db/Database.php:606
Stack trace:
#0 /usr/share/mediawiki1.7/includes/db/Database.php(561): Database->reportQueryError('Can't connect t...', 2002, 'SELECT old_tex...', 'Revision::loadT...', false)
#1 /usr/share/mediawiki1.7/includes/db/Database.php(969): Database->query('SELECT old_tex...', 'Revision::loadT...')
#2 /usr/share/mediawiki1.7/includes/db/Database.php(1045): Database->select('text', Array, Array, 'Revision::loadT...', Array, Array)
#3 /usr/share/mediawiki1.7/includes/Revision.php(816): Database->selectRow('text', Array, Array, 'Revision::loadT...')
#4 /usr/share/mediawiki1.7/includes/Revision.php(523): Revision->loadText()
#5 /usr/share/mediawiki1.7/includes/Revision.php(512): Revision->getRawText()
#6 /usr/share/mediawiki1.7/includes/parser/Parser.php(3118): Revision->getText()
#7 [internal function]: Parser->statelessFetchTemplate(Object(Title), Object(Parser))
#8 /usr/share/mediawiki1.7/includes/parser/Parser.php(3065): call_user_func(Array, Object(Title), Object(Parser))
#9 /usr/share/mediawiki1.7/includes/parser/Parser.php(3042): Parser->fetchTemplateAndTitle(Object(Title))
#10 /usr/share/mediawiki1.7/includes/parser/Parser.php(2929): Parser->getTemplateDom(Object(Title))
#11 /usr/share/mediawiki1.7/includes/parser/Preprocessor_DOM.php(915): Parser->braceSubstitution(Array, Object(PPFrame_DOM))
#12 /usr/share/mediawiki1.7/includes/parser/Parser.php(2674): PPFrame_DOM->expand(Object(PPNode_DOM), 0)
#13 /usr/share/mediawiki1.7/includes/parser/Parser.php(962): Parser->replaceVariables('{{stub}}??See [...')
#14 /usr/share/mediawiki1.7/includes/parser/Parser.php(317): Parser->internalParse('{{stub}}??See [...')
#15 /usr/share/mediawiki1.7/includes/Article.php(3384): Parser->parse('{{stub}}??See [...', Object(Title), Object(ParserOptions), true, true, 18134)
#16 /usr/share/mediawiki1.7/includes/Article.php(875): Article->outputWikiText('{{stub}}??See [...', false)
#17 /usr/share/mediawiki1.7/includes/Wiki.php(437): Article->view()
#18 /usr/share/mediawiki1.7/includes/Wiki.php(59): MediaWiki->performAction(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebRequest))
#19 /var/lib/mediawiki1.7/index.php(93): MediaWiki->initialize(Object(Title), Object(Article), Object(OutputPage), Object(User), Object(WebRequest))
#20 {main}

Exception caught inside exception handler: exception 'DBUnexpectedError' with message 'Error in fetchObject(): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) (localhost)' in /usr/share/mediawiki1.7/includes/db/Database.php:735
Stack trace:
#0 /usr/share/mediawiki1.7/includes/db/Database.php(2620): Database->fetchObject(false)
#1 /usr/share/mediawiki1.7/includes/LinkBatch.php(98): ResultWrapper->fetchObject()
#2 /usr/share/mediawiki1.7/includes/LinkBatch.php(78): LinkBatch->addResultToCache(Object(LinkCache), Object(ResultWrapper))
#3 /usr/share/mediawiki1.7/includes/LinkBatch.php(68): LinkBatch->executeInto(Object(LinkCache))
#4 /usr/share/mediawiki1.7/includes/Skin.php(208): LinkBatch->execute()
#5 /usr/share/mediawiki1.7/includes/Skin.php(184): Skin->preloadExistence()
#6 /usr/share/mediawiki1.7/includes/SkinTemplate.php(106): Skin->initPage(Object(OutputPage))
#7 /usr/share/mediawiki1.7/skins/MonoBook.php(24): SkinTemplate->initPage(Object(OutputPage))
#8 /usr/share/mediawiki1.7/includes/SkinTemplate.php(151): SkinMonoBook->initPage(Object(OutputPage))
#9 /usr/share/mediawiki1.7/includes/OutputPage.php(821): SkinTemplate->outputPage(Object(OutputPage))
#10 /usr/share/mediawiki1.7/includes/Exception.php(150): OutputPage->output()
#11 /usr/share/mediawiki1.7/includes/Exception.php(174): MWException->reportHTML()
#12 /usr/share/mediawiki1.7/includes/Exception.php(260): MWException->report()
#13 /usr/share/mediawiki1.7/includes/Exception.php(294): wfReportException(Object(DBQueryError))
#14 [internal function]: wfExceptionHandler(Object(DBQueryError))
#15 {main}