Locking a node caches its data and the data from its inputs and prevents them from being recalculating during cooking. This is very useful to increase cooking efficiency once a static bit of the network is finished and won’t be edited.
This is much more convenient than deleting history, because you can go back later and unlock the history to edit it.
Normally Houdini prevents you from editing locked nodes. This is called a hard lock. You can optionally switch to a soft lock that allows a subset of manual modeling changes to be made while maintaining the network integrity. Houdini can only maintain a soft lock if the geometry’s topology doesn’t change.
In the network editor, inside , click the lock icon on the node’s tile to lock or unlock the node. When you unlock a node, Houdini asks you if you would like to unlock or soft lock the geometry.
Locking nodes is memory efficient for most purposes, and has the convenience of allowing you to unlock the node later for editing. However, you can actually delete history for some node types, collapsing the effects of previous nodes into baked data, by pressing on an object in the viewport and choosing Delete History.
This converts the node into a container for the baked data. The parameters on the node no longer have any effect.