> For the complete documentation index, see [llms.txt](https://advion.gitbook.io/advion-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://advion.gitbook.io/advion-docs/database-and-migration.md).

# Database and Migration

IslandHologram stores island hologram state in SQLite.

The database file is created inside the plugin data folder:

```
plugins/IslandHologram/data.db
```

## Runtime Libraries

Paper loads the database libraries through `plugin.yml`:

```yaml
libraries:
  - org.xerial:sqlite-jdbc:3.45.3.0
  - com.zaxxer:HikariCP:5.1.0
```

The plugin uses HikariCP with a small SQLite connection pool.

## Stored Data

IslandHologram stores:

| Data                    | Purpose                                         |
| ----------------------- | ----------------------------------------------- |
| Registered island UUIDs | Determines which islands should have holograms. |
| Disabled island UUIDs   | Remembers `/isholo toggle` disabled states.     |

The plugin does not store hologram text in the database. Hologram content comes from `config.yml`.

## When to Run Migration

Run:

```
/isholo migrate
```

when installing IslandHologram on a server where SuperiorSkyblock2 islands already exist.

You usually do not need to run migration for new islands created after IslandHologram is installed. New islands are registered automatically from SuperiorSkyblock2 island creation events.

## Migration Flow

During migration, IslandHologram:

1. reads all existing SuperiorSkyblock2 islands;
2. loads already registered island UUIDs from SQLite;
3. saves missing island UUIDs in batches;
4. registers migrated islands in memory;
5. allows the proximity task to spawn holograms when players are nearby.

## Island Removal and Reset

When an island is disbanded, IslandHologram:

* removes it from active tracking;
* despawns its hologram;
* deletes the registered island UUID;
* removes the disabled flag if one exists.

When an island world is reset, IslandHologram despawns the hologram and lets the proximity task spawn it again later when the world is ready.

## Backups

Before plugin updates or large migrations, back up:

```
plugins/IslandHologram/config.yml
plugins/IslandHologram/data.db
```


---

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