# Rezoom.SQL.Migrations

[Home](/rezoom-sql/master.md) > [API](/rezoom-sql/api.md) > Rezoom.SQL.Migrations

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## Rezoom.SQL.Migrations

This namespace contains the migration configuration and some types representing migrations within your data model.

### The `MigrationConfig` type

This is a record type with the following properties:

#### AllowRetroactiveMigrations : bool

If true, permit running migrations that have not been run on the database, but are older than other migrations that *have* been run. Typically this would only make sense in development, after merging migrations written by another developer.

See also the section on [migration trees](/rezoom-sql/configuration/migrationtrees.md).

#### LogMigrationRan : Migration -> unit

This is a function which will be called after a migration has been run. Often it is nice to print the migration name to the console or perhaps to a text file.

### MigrationConfig defaults

The static member `MigrationConfig.Default` is suitable for most typical usages. It is defined as:

```fsharp
{   AllowRetroactiveMigrations = false
    LogMigrationRan = fun _ -> ()
}
```

***

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