$hash: hash of user options applied to the page, see ParserOptions::optionsHash()
ex: wikidb:pcache:idhash:1-0!1!0!!en!2
stores: ParserOutput object
- modified by: Article::editUpdates() or Article::getOutputFromWikitext()
+ modified by: WikiPage::doEditUpdates() or PoolWorkArticleView::doWork()
expiry: $wgParserCacheExpireTime or less if it contains short lived functions
key: $wgDBname:pcache:idoptions:$pageid