<!---
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing,
  software distributed under the License is distributed on an
  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  KIND, either express or implied.  See the License for the
  specific language governing permissions and limitations
  under the License.
-->

# Upgrade Guides

## DataFusion 55.0.0

**Note:** DataFusion `55.0.0` 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.

### `is_dynamic_physical_expr` is deprecated

`datafusion_physical_expr_common::physical_expr::is_dynamic_physical_expr` is
deprecated. It was a thin wrapper over `snapshot_generation(expr) != 0` used to
ask "does this predicate contain a dynamic filter?".

Prefer asking the question directly against the concrete type. For a one-off
check, downcast to `DynamicFilterPhysicalExpr`:

```rust
use datafusion_physical_expr::expressions::DynamicFilterPhysicalExpr;
use datafusion_common::tree_node::{TreeNode, TreeNodeRecursion};

let mut is_dynamic = false;
predicate.apply(|e| {
    if e.downcast_ref::<DynamicFilterPhysicalExpr>().is_some() {
        is_dynamic = true;
        Ok(TreeNodeRecursion::Stop)
    } else {
        Ok(TreeNodeRecursion::Continue)
    }
})?;
```

If you also need to know whether the dynamic filters can still change (and to be
notified when they do), use the new `DynamicFilterTracking` /
`DynamicFilterTracker` API in `datafusion_physical_expr`:

```rust
use datafusion_physical_expr::DynamicFilterTracking;

let tracking = DynamicFilterTracking::classify(&predicate);
if tracking.contains_dynamic_filter() {
    // worth re-evaluating the predicate at runtime
}
```

### `FilePruner::try_new` no longer builds a pruner for static predicates without statistics

`datafusion_pruning::FilePruner::try_new` now returns `None` when the predicate
is purely static _and_ the file carries no usable column statistics, because
such a pruner can never prune anything beyond what planning already did.
Previously it returned `Some` whenever a statistics struct was present (the
"is this worth pruning?" decision lived in the Parquet opener). Files with column
statistics, and predicates that carry a dynamic filter, are unaffected.