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# Upgrade Guides

## DataFusion 54.0.0

**Note:** DataFusion `54.0.0` has not been released yet. The information provided
in this section pertains to features and changes that have already been merged
to the main branch and are awaiting release in this version.

### `ExecutionPlan::apply_expressions` is now a required method

`apply_expressions` has been added as a **required** method on the `ExecutionPlan` trait (no default implementation). The same applies to the `FileSource` and `DataSource` traits. Any custom implementation of these traits must now implement `apply_expressions`.

**Who is affected:**

- Users who implement custom `ExecutionPlan` nodes
- Users who implement custom `FileSource` or `DataSource` sources

**Migration guide:**

Add `apply_expressions` to your implementation. Call `f` on each top-level `PhysicalExpr` your node owns, using `visit_sibling` to correctly propagate `TreeNodeRecursion`:

**Node with no expressions:**

```rust,ignore
fn apply_expressions(
    &self,
    _f: &mut dyn FnMut(&dyn PhysicalExpr) -> Result<TreeNodeRecursion>,
) -> Result<TreeNodeRecursion> {
    Ok(TreeNodeRecursion::Continue)
}
```

**Node with a single expression:**

```rust,ignore
fn apply_expressions(
    &self,
    f: &mut dyn FnMut(&dyn PhysicalExpr) -> Result<TreeNodeRecursion>,
) -> Result<TreeNodeRecursion> {
    f(self.predicate.as_ref())
}
```

**Node with multiple expressions:**

```rust,ignore
fn apply_expressions(
    &self,
    f: &mut dyn FnMut(&dyn PhysicalExpr) -> Result<TreeNodeRecursion>,
) -> Result<TreeNodeRecursion> {
    let mut tnr = TreeNodeRecursion::Continue;
    for expr in &self.expressions {
        tnr = tnr.visit_sibling(|| f(expr.as_ref()))?;
    }
    Ok(tnr)
}
```

**Node whose only expressions are in `output_ordering()` (e.g. a synthetic test node with no owned expression fields):**

```rust,ignore
fn apply_expressions(
    &self,
    f: &mut dyn FnMut(&dyn PhysicalExpr) -> Result<TreeNodeRecursion>,
) -> Result<TreeNodeRecursion> {
    let mut tnr = TreeNodeRecursion::Continue;
    if let Some(ordering) = self.cache.output_ordering() {
        for sort_expr in ordering {
            tnr = tnr.visit_sibling(|| f(sort_expr.expr.as_ref()))?;
        }
    }
    Ok(tnr)
}
```