CantStopTheSignalWhy can't cached pages be shown in lieu of error pages, if they exist? There's a perfectly good copy of the page in cache, why show a database error page?
The wp-cache (or super-cache?) engine would just need to include a comment tag in the html source that a database error occured and the page is from cache. If the cache is expired, then still show it anyway, but also output the 500 header. Otherwise 200 header if the page isn't otherwise expired.
And don't delete expired pages until a current copy is available to replace it. (In other words, if a database error occurs, show expired cache pages instead of error page.)
Only if there is no cached page for the request would I want to have an error page appear when the database is not accessible.
This feature would wildly make WP capable of high-availability in high traffic situations.
