# `TiDB Lightning`: Task Parameters for Import Modes and Parallel Import
+ Section: **`[tikv-importer]`**
+ Parameters: 
  + **`backend = "local|tidb"`**
  + **`incremental-import = false|true`**
  + **`sorted-kv-dir`**: The directory of local `KV` sorting in the physical import mode
  + **`range-concurrency`**: The concurrency that `TiKV` writes KV data in the physical import mode
+ Description: 
  + **`backend = "local"`**: Physical import mode, used by default
  + **`backend = "tidb"`**: Logical import mode
  + **`incremental-import = false`**: Creating table with data
  + **`incremental-import = true`**: Importing data to existing table, hence supporting **parallel import**
+ For example, attempting to import data into existing table with **`incremental-import = false`**:
```
...
~!@tidb lightning encountered error:@!~ 
[Lightning:PreCheck:ErrPreCheckFailed]tidb-lightning pre-check failed: 
table(s) [`universe`.`moons`, `universe`.`planet_categories`, `universe`.`planets`, `universe`.`stars`] ~!@are not empty@!~
```

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Parameter `backend`:
- `"local"`: Physical import mode, used by default. It applies to large dataset import, for example, greater than `1 TiB`. However, during the import, downstream `TiDB` is not available to provide services.
- `"tidb"`: Logical import mode. You can use this mode for small dataset import, for example, smaller than `1 TiB`. During the import, downstream `TiDB` is available to provide services.

Parameter `incremental-import`:
- `true`: When you use parallel import mode, you must set it to `true`, because multiple `TiDB Lightning` instances are importing the same table at the same time.
- `false`: The default value is `false`, the non-parallel import mode and cannot import data into existing table.

Parameter `sorted-kv-dir`:
- The directory of local `KV` sorting in the physical import mode.