==Node Table==
BaseX stores all XML nodes in a flat table. The node table of a database can be displayed via the [[Commands#INFO STORAGE{{Command|INFO STORAGE]] }} command:
<pre>
</pre>
The [[{{Function|Database Module#db:node-pre|db:node-pre]] }} and [[{{Function|Database Module#db:node-id|db:node-id]] }} functions can be called to retrieve the ''pre'' and ''id'' values of a node, and [[{{Function|Database Module#db:open-pre|db:open-pre]] }} and [[{{Function|Database Module#db:open-id|db:open-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==