</pre>
The {{Function|Database|db:node-pre}} and {{Function|Database|db:node-id}} functions can be called to retrieve the ''pre'' and ''id'' values of a node, and {{Function|Database|db:preget-pre}} and {{Function|Database|db:preget-id}} can be used to go back and retrieve the original node. By default, ''id'' lookups are expensive. If {{Option|UPDINDEX}} is turned on, an additional index will be maintained to speed up the process.
==Block Storage==