Document SqlRenderer::render_alter_column()
@@ -27,5 +27,9 @@ pub(crate) trait SqlRenderer {
fn render_default<'a>(&self, default: &'a DefaultValue, family: &ColumnTypeFamily) -> Cow<'a, str>;
+ /// Attempt to render a database-specific ALTER COLUMN based on the
+ /// passed-in differ. `None` means that we could not generate a good (set
+ /// of) ALTER COLUMN(s), and we should fall back to dropping and recreating
+ /// the column.
fn render_alter_column(&self, differ: &ColumnDiffer<'_>) -> Option<Vec<String>>;
}
