> ## Documentation Index
> Fetch the complete documentation index at: https://docs.exmergo.com/llms.txt
> Use this file to discover all available pages before exploring further.

# dex maintain

> Reference for dex maintain: snapshot a baseline, check schema, volume, grain, and semantic drift, verify a project, and reconcile with proposed diffs.

detect drift against the last snapshot and propose the fix

## dex maintain snapshot

Pin the current map and fingerprint the project layers as the baseline drift is measured against. `--project-only` opens no connection.

```text theme={null}
dex maintain snapshot [--project-only]
```

**Options**

| Option | Description | Default |
| - | - | - |
| `--project-only` | refingerprint only the project layers; opens no connection | |

## dex maintain check

Run every drift axis against the snapshot and rank the findings. The free axes always run; the scanning axes are offered with an estimate.

```text theme={null}
dex maintain check [<object> ...]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[<object> ...]` | object to check (default: the whole project) | |

## dex maintain schema

Compare structure against the snapshot: columns, tables, nullability, dangling sources and changed models. Free metadata.

```text theme={null}
dex maintain schema [<object> ...]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[<object> ...]` | object to check (default: the whole project) | |

## dex maintain volume

Compare row counts against the snapshot from free metadata. Objects with no maintained count, such as views, are named as not compared.

```text theme={null}
dex maintain volume [<object> ...]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[<object> ...]` | object to check (default: the whole project) | |

## dex maintain grain

Re-measure key uniqueness, grain and join fanout, plus declared grains. Scans the data, so it is billed on metered connectors.

```text theme={null}
dex maintain grain [<object> ...]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[<object> ...]` | object to check (default: the whole project) | |

## dex maintain semantic

Report changed, added and removed semantic definitions and references that no longer resolve, for free. Dimension cardinality change is a scan, offered with an estimate.

```text theme={null}
dex maintain semantic [<object> ...]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[<object> ...]` | object to check (default: the whole project) | |

## dex maintain reconcile

Store the reconciling edits as a plan of diffs tagged mechanical or advisory. Never applied here; use transform apply. Repo-only.

```text theme={null}
dex maintain reconcile [{schema,volume,grain,semantic}]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[{schema,volume,grain,semantic}]` | reconcile only this drift class (default: all) | |

## dex maintain verify

Check build status, column contracts, row population, grain and join contracts against the built relations. Mostly free metadata; view row counts and join probes are offered with an estimate.

```text theme={null}
dex maintain verify [<object> ...]
```

**Arguments**

| Argument | Description | Default |
| - | - | - |
| `[<object> ...]` | dbt selector to verify (default: the whole project) | |

Every command here also accepts the [global options](/dex/cli/overview#global-options).

Source: [`packages/dex-core/src/exmergo_dex_core/cli.py`](https://github.com/exmergo/dex/blob/v1.14.1/packages/dex-core/src/exmergo_dex_core/cli.py) ([edit on main](https://github.com/exmergo/dex/edit/main/packages/dex-core/src/exmergo_dex_core/cli.py)). This page is generated; change the source, not the site.


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