https://github.com/delta-io/delta-rs/pull/2327

crates/core/src/kernel/models/actions.rs

@@ -671,6 +671,26 @@ pub struct Txn {
     pub last_updated: Option<i64>,
 }
 
+impl Txn {
+    /// Create a new application transactions. See [`Txn`] for details.
+    pub fn new(app_id: &dyn ToString, version: i64) -> Self {
+        Self::new_with_last_update(app_id, version, None)
+    }
+
+    /// Create a new application transactions. See [`Txn`] for details.
+    pub fn new_with_last_update(
+        app_id: &dyn ToString,
+        version: i64,
+        last_updated: Option<i64>,
+    ) -> Self {
+        Txn {
+            app_id: app_id.to_string(),
+            version,
+            last_updated,
+        }
+    }
+}
+
 /// The commitInfo is a fairly flexible action within the delta specification, where arbitrary data can be stored.
 /// However the reference implementation as well as delta-rs store useful information that may for instance
 /// allow us to be more permissive in commit conflict resolution.

crates/core/src/kernel/snapshot/log_segment.rs

@@ -30,9 +30,12 @@ lazy_static! {
     pub(super) static ref COMMIT_SCHEMA: StructType = StructType::new(vec![
         ActionType::Add.schema_field().clone(),
         ActionType::Remove.schema_field().clone(),
+        ActionType::Txn.schema_field().clone(),
+    ]);
+    pub(super) static ref CHECKPOINT_SCHEMA: StructType = StructType::new(vec![
+        ActionType::Add.schema_field().clone(),
+        ActionType::Txn.schema_field().clone(),
     ]);
-    pub(super) static ref CHECKPOINT_SCHEMA: StructType =
-        StructType::new(vec![ActionType::Add.schema_field().clone(),]);
     pub(super) static ref TOMBSTONE_SCHEMA: StructType =
         StructType::new(vec![ActionType::Remove.schema_field().clone(),]);
 }

crates/core/src/kernel/snapshot/mod.rs

@@ -197,10 +197,11 @@ impl Snapshot {
     }
 
     /// Get the files in the snapshot
-    pub fn files(
+    pub fn files<'a>(
         &self,
         store: Arc<dyn ObjectStore>,
-    ) -> DeltaResult<ReplayStream<BoxStream<'_, DeltaResult<RecordBatch>>>> {
+        visitors: Vec<&'a mut dyn ReplayVisitor>,
+    ) -> DeltaResult<ReplayStream<'a, BoxStream<'_, DeltaResult<RecordBatch>>>> {
         let log_stream = self.log_segment.commit_stream(
             store.clone(),
             &log_segment::COMMIT_SCHEMA,
@@ -211,7 +212,7 @@ impl Snapshot {
             &log_segment::CHECKPOINT_SCHEMA,
             &self.config,
         );
-        ReplayStream::try_new(log_stream, checkpoint_stream, self)
+        ReplayStream::try_new(log_stream, checkpoint_stream, self, visitors)
     }
 
     /// Get the commit infos in the snapshot
@@ -331,6 +332,12 @@ impl Snapshot {
     }
 }
 
+/// Allows hooking into the reading of commit files and checkpoints whenever a table is loaded or updated.
+pub trait ReplayVisitor: Send {
+    /// Process a batch
+    fn visit_batch(&mut self, batch: &RecordBatch) -> DeltaResult<()>;
+}
+
 /// A snapshot of a Delta table that has been eagerly loaded into memory.
 #[derive(Debug, Clone, PartialEq)]
 pub struct EagerSnapshot {
@@ -347,9 +354,20 @@ impl EagerSnapshot {
         store: Arc<dyn ObjectStore>,
         config: DeltaTableConfig,
         version: Option<i64>,
+    ) -> DeltaResult<Self> {
+        Self::try_new_with_visitor(table_root, store, config, version, vec![]).await
+    }
+
+    /// Create a new [`EagerSnapshot`] instance
+    pub async fn try_new_with_visitor(
+        table_root: &Path,
+        store: Arc<dyn ObjectStore>,
+        config: DeltaTableConfig,
+        version: Option<i64>,
+        visitors: Vec<&mut dyn ReplayVisitor>,
     ) -> DeltaResult<Self> {
         let snapshot = Snapshot::try_new(table_root, store.clone(), config, version).await?;
-        let files = snapshot.files(store)?.try_collect().await?;
+        let files = snapshot.files(store, visitors)?.try_collect().await?;
         Ok(Self { snapshot, files })
     }
 
@@ -368,14 +386,16 @@ impl EagerSnapshot {
     }
 
     /// Update the snapshot to the given version
-    pub async fn update(
+    pub async fn update<'a>(
         &mut self,
         log_store: Arc<dyn LogStore>,
         target_version: Option<i64>,
+        visitors: Vec<&'a mut dyn ReplayVisitor>,
     ) -> DeltaResult<()> {
         if Some(self.version()) == target_version {
             return Ok(());
         }
+
         let new_slice = self
             .snapshot
             .update_inner(log_store.clone(), target_version)
@@ -399,10 +419,11 @@ impl EagerSnapshot {
                     .boxed()
             };
             let mapper = LogMapper::try_new(&self.snapshot)?;
-            let files = ReplayStream::try_new(log_stream, checkpoint_stream, &self.snapshot)?
-                .map(|batch| batch.and_then(|b| mapper.map_batch(b)))
-                .try_collect()
-                .await?;
+            let files =
+                ReplayStream::try_new(log_stream, checkpoint_stream, &self.snapshot, visitors)?
+                    .map(|batch| batch.and_then(|b| mapper.map_batch(b)))
+                    .try_collect()
+                    .await?;
 
             self.files = files;
         }
@@ -476,6 +497,7 @@ impl EagerSnapshot {
     pub fn advance<'a>(
         &mut self,
         commits: impl IntoIterator<Item = &'a CommitData>,
+        mut visitors: Vec<&'a mut dyn ReplayVisitor>,
     ) -> DeltaResult<i64> {
         let mut metadata = None;
         let mut protocol = None;
@@ -506,7 +528,11 @@ impl EagerSnapshot {
         let mut scanner = LogReplayScanner::new();
 
         for batch in actions {
-            files.push(scanner.process_files_batch(&batch?, true)?);
+            let batch = batch?;
+            files.push(scanner.process_files_batch(&batch, true)?);
+            for visitor in &mut visitors {
+                visitor.visit_batch(&batch)?;
+            }
         }
 
         let mapper = LogMapper::try_new(&self.snapshot)?;
@@ -652,7 +678,7 @@ mod tests {
         assert_eq!(tombstones.len(), 31);
 
         let batches = snapshot
-            .files(store.clone())?
+            .files(store.clone(), vec![])?
             .try_collect::<Vec<_>>()
             .await?;
         let expected = [
@@ -778,9 +804,10 @@ mod tests {
             predicate: None,
         };
 
-        let actions = vec![CommitData::new(removes, operation, HashMap::new()).unwrap()];
+        let actions =
+            vec![CommitData::new(removes, operation, HashMap::new(), Vec::new()).unwrap()];
 
-        let new_version = snapshot.advance(&actions)?;
+        let new_version = snapshot.advance(&actions, vec![])?;
         assert_eq!(new_version, version + 1);
 
         let new_files = snapshot.file_actions()?.map(|f| f.path).collect::<Vec<_>>();

crates/core/src/kernel/snapshot/replay.rs

@@ -23,14 +23,17 @@ use crate::kernel::arrow::extract::{self as ex, ProvidesColumnByName};
 use crate::kernel::arrow::json;
 use crate::{DeltaResult, DeltaTableConfig, DeltaTableError};
 
+use super::ReplayVisitor;
 use super::Snapshot;
 
 pin_project! {
-    pub struct ReplayStream<S> {
+    pub struct ReplayStream<'a, S> {
         scanner: LogReplayScanner,
 
         mapper: Arc<LogMapper>,
 
+        visitors: Vec<&'a mut dyn ReplayVisitor>,
+
         #[pin]
         commits: S,
 
@@ -39,8 +42,13 @@ pin_project! {
     }
 }
 
-impl<S> ReplayStream<S> {
-    pub(super) fn try_new(commits: S, checkpoint: S, snapshot: &Snapshot) -> DeltaResult<Self> {
+impl<'a, S> ReplayStream<'a, S> {
+    pub(super) fn try_new(
+        commits: S,
+        checkpoint: S,
+        snapshot: &Snapshot,
+        visitors: Vec<&'a mut dyn ReplayVisitor>,
+    ) -> DeltaResult<Self> {
         let stats_schema = Arc::new((&snapshot.stats_schema()?).try_into()?);
         let mapper = Arc::new(LogMapper {
             stats_schema,
@@ -50,6 +58,7 @@ impl<S> ReplayStream<S> {
             commits,
             checkpoint,
             mapper,
+            visitors,
             scanner: LogReplayScanner::new(),
         })
     }
@@ -127,7 +136,7 @@ fn map_batch(
     Ok(batch)
 }
 
-impl<S> Stream for ReplayStream<S>
+impl<'a, S> Stream for ReplayStream<'a, S>
 where
     S: Stream<Item = DeltaResult<RecordBatch>>,
 {
@@ -136,19 +145,33 @@ where
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         let this = self.project();
         let res = this.commits.poll_next(cx).map(|b| match b {
-            Some(Ok(batch)) => match this.scanner.process_files_batch(&batch, true) {
-                Ok(filtered) => Some(this.mapper.map_batch(filtered)),
-                Err(e) => Some(Err(e)),
-            },
+            Some(Ok(batch)) => {
+                for visitor in this.visitors.iter_mut() {
+                    if let Err(e) = visitor.visit_batch(&batch) {
+                        return Some(Err(e));
+                    }
+                }
+                match this.scanner.process_files_batch(&batch, true) {
+                    Ok(filtered) => Some(this.mapper.map_batch(filtered)),
+                    Err(e) => Some(Err(e)),
+                }
+            }
             Some(Err(e)) => Some(Err(e)),
             None => None,
         });
         if matches!(res, Poll::Ready(None)) {
             this.checkpoint.poll_next(cx).map(|b| match b {
-                Some(Ok(batch)) => match this.scanner.process_files_batch(&batch, false) {
-                    Ok(filtered) => Some(this.mapper.map_batch(filtered)),
-                    Err(e) => Some(Err(e)),
-                },
+                Some(Ok(batch)) => {
+                    for visitor in this.visitors.iter_mut() {
+                        if let Err(e) = visitor.visit_batch(&batch) {
+                            return Some(Err(e));
+                        }
+                    }
+                    match this.scanner.process_files_batch(&batch, false) {
+                        Ok(filtered) => Some(this.mapper.map_batch(filtered)),
+                        Err(e) => Some(Err(e)),
+                    }
+                }
                 Some(Err(e)) => Some(Err(e)),
                 None => None,
             })