# reindex

Convert an existing index's evidence representation in place, between exact and approximate.

```bash
obikmer reindex INDEX [OPTIONS]
```

## Arguments

| Argument | Description |
|---|---|
| `INDEX` | Index directory to convert (modified in place) |

## Options

| Option | Default | Description |
|---|---|---|
| `--approx` | off | Convert to approximate evidence (default direction is approximate → exact); requires `-z`/`--evidence-bits`/`--fp` |
| `-z, --findere-z` | none | Findere z parameter (≥ 1) |
| `--evidence-bits` | none | Fingerprint bits per slot (b) |
| `--fp` | none | Target false-positive rate per z-window |
| `--block-size` | `1` | Block size for the exact on-disk index (ignored when converting to approximate) |

See [`index`](index_command.md#exact-vs-approximate-evidence) for the exact/approximate trade-off and the underlying false-positive model, and [`estimate`](estimate.md) to explore parameters beforehand. The index directory is locked for exclusive access during conversion.