01 MCA Selector changes stored world data
MCA Selector is an external editor for Minecraft Java Edition worlds. Its project wiki ↗ describes selecting, exporting, deleting and editing chunks or regions. It is not a Bedrock world editor and is not the same as pressing F3+A to refresh the client view.
Use it only when you have a clear world-maintenance objective: for example, removing selected unused terrain from a working copy. Check its supported world versions before opening a save from a newer Minecraft build. A program opening a folder without an immediate error is not enough to establish that every data format is supported.
02 Make an untouched full-world copy before selecting anything
- Notify players, save through the supported controls and stop the server cleanly.
- Copy the complete world and record its game build, generator and required mods.
- Keep one untouched archive outside the live server directory.
- Open a second working copy in MCA Selector, not the live production world.
- Confirm the intended dimension and sample known coordinates before making a selection.
Do not copy just region files and assume player data, entities or points of interest can be reconstructed later. A complete recovery copy is easier to reason about than a hand-selected collection of files whose relationships you have not verified. The restore checklist describes how to validate that copy independently.
03 Treat low inhabited time as a clue, not proof of no builds
The filter documentation ↗ explains InhabitedTime, coordinates and other selection conditions. A low inhabited-time threshold can help find lightly used chunks, but it does not certify that they contain nothing valuable. A road, portal connection or briefly visited structure can still matter to players.
Preview the selected area and exclude protected bases, transport routes and border features deliberately. Export selected chunks to a separate empty destination if you need a focused inspection copy. Keep the original full-world archive as the authoritative rollback source; a selective export does not replace it.
The project states deletion changes original files and cannot be undone without a backup. Review the selection immediately before committing. A filter expression copied from somebody else’s map is not a safe default for yours.
04 Test the edited copy before replacing production
Run the edited world in an isolated server using a compatible build and required mods. Visit retained bases and the boundary of the removed area; check entities, transport and player progress. If you intend deleted terrain to regenerate, inspect the new generation boundary under the intended generator.
Do not allow real production play to continue in both old and edited worlds while deciding which one is authoritative. Choose a maintenance window, retain the old version and replace only after the copy passes. A client-only visual problem belongs to chunk reload diagnostics; large-scale generation planning belongs to Chunky. Neither task justifies deleting stored terrain as a first response.