feat: expose peek next commit function to python

crates/deltalake-core/src/errors.rs

@@ -76,6 +76,10 @@ pub enum DeltaTableError {
     #[error("Invalid table version: {0}")]
     InvalidVersion(i64),
 
+    /// Error returned when the DeltaTable has no delta log version.
+    #[error("Delta log not found for table version: {0}")]
+    DeltaLogNotFound(i64),
+
     /// Error returned when the DeltaTable has no data files.
     #[error("Corrupted table, cannot read data file {}: {}", .path, .source)]
     MissingDataFile {

crates/deltalake-core/src/table/mod.rs

@@ -6,6 +6,7 @@ use std::fmt;
 use std::fmt::Formatter;
 use std::{cmp::max, cmp::Ordering, collections::HashSet};
 
+use bytes::Bytes;
 use chrono::{DateTime, Utc};
 use futures::StreamExt;
 use lazy_static::lazy_static;
@@ -455,6 +456,23 @@ impl DeltaTable {
         self.update().await
     }
 
+    /// Get the commit obj from the version
+    pub async fn get_obj_from_version(
+        &self,
+        current_version: i64,
+    ) -> Result<Bytes, DeltaTableError> {
+        let commit_log_bytes = match self.log_store.read_commit_entry(current_version).await {
+            Ok(bytes) => Ok(bytes),
+            Err(DeltaTableError::ObjectStore {
+                source: ObjectStoreError::NotFound { .. },
+            }) => {
+                return Err(DeltaTableError::DeltaLogNotFound(current_version));
+            }
+            Err(err) => Err(err),
+        }?;
+        Ok(commit_log_bytes)
+    }
+
     /// Get the list of actions for the next commit
     pub async fn peek_next_commit(
         &self,

crates/deltalake-core/tests/data/simple_table_missing_commit/_delta_log/00000000000000000000.json

@@ -0,0 +1,4 @@
+{"commitInfo":{"timestamp":1587968586154,"operation":"WRITE","operationParameters":{"mode":"ErrorIfExists","partitionBy":"[]"},"isBlindAppend":true}}
+{"protocol":{"minReaderVersion":1,"minWriterVersion":2}}
+{"metaData":{"id":"5fba94ed-9794-4965-ba6e-6ee3c0d22af9","format":{"provider":"parquet","options":{}},"schemaString":"{\"type\":\"struct\",\"fields\":[{\"name\":\"id\",\"type\":\"long\",\"nullable\":true,\"metadata\":{}}]}","partitionColumns":[],"configuration":{},"createdTime":1587968585495}}
+{"add":{"path":"part-00000-a72b1fb3-f2df-41fe-a8f0-e65b746382dd-c000.snappy.parquet","partitionValues":{},"size":262,"modificationTime":1587968586000,"dataChange":true}}

crates/deltalake-core/tests/data/simple_table_missing_commit/_delta_log/00000000000000000001.json

@@ -0,0 +1,2 @@
+{"commitInfo":{"timestamp":1587968596254,"operation":"MERGE","operationParameters":{"predicate":"(oldData.`id` = newData.`id`)"},"readVersion":0,"isBlindAppend":false}}
+{"add":{"path":"part-00004-95c9bc2c-ac85-4581-b3cc-84502b0c314f-c000.snappy.parquet","partitionValues":{},"size":429,"modificationTime":1587968596000,"dataChange":true}}

crates/deltalake-core/tests/data/simple_table_missing_commit/_delta_log/00000000000000000003.json

@@ -0,0 +1,2 @@
+{"commitInfo":{"timestamp":1587968614187,"operation":"UPDATE","operationParameters":{"predicate":"((id#697L % cast(2 as bigint)) = cast(0 as bigint))"},"readVersion":2,"isBlindAppend":false}}
+{"add":{"path":"part-00001-bb70d2ba-c196-4df2-9c85-f34969ad3aa9-c000.snappy.parquet","partitionValues":{},"size":429,"modificationTime":1587968614000,"dataChange":true}}

python/deltalake/_internal.pyi

@@ -42,6 +42,7 @@ class RawDeltaTable:
     ) -> str: ...
     def table_uri(self) -> str: ...
     def version(self) -> int: ...
+    def get_obj(self, version: int) -> bytes: ...
     def get_latest_version(self) -> int: ...
     def metadata(self) -> RawDeltaTableMetaData: ...
     def protocol_versions(self) -> List[int]: ...

python/deltalake/table.py

@@ -42,7 +42,7 @@
 from deltalake._internal import create_deltalake as _create_deltalake
 from deltalake._util import encode_partition_value
 from deltalake.data_catalog import DataCatalog
-from deltalake.exceptions import DeltaProtocolError
+from deltalake.exceptions import DeltaError, DeltaProtocolError
 from deltalake.fs import DeltaStorageHandler
 from deltalake.schema import Schema as DeltaSchema
 
@@ -256,6 +256,7 @@ def __init__(
 
         """
         self._storage_options = storage_options
+        self._latest_version = -1
         self._table = RawDeltaTable(
             str(table_uri),
             version=version,
@@ -897,6 +898,36 @@ def update_incremental(self) -> None:
         """
         self._table.update_incremental()
 
+    def get_latest_version(self) -> int:
+        """
+        Get latest version of commit.
+        """
+        return self._table.get_latest_version()
+
+    def peek_next_commit(
+        self, version: int
+    ) -> Tuple[Optional[List[Dict[Any, Any]]], int]:
+        """
+        Peek next commit of the input version.
+        """
+        actions = []
+        next_version = version + 1
+        if next_version > self._latest_version:
+            self._latest_version = self.get_latest_version()
+        while next_version <= self._latest_version:
+            try:
+                commit_log_bytes = self._table.get_obj(next_version)
+                for commit_action in commit_log_bytes.split(b"\n"):
+                    if commit_action:
+                        actions.append(json.loads(commit_action))
+                return actions, next_version
+            except DeltaError as e:
+                if str(e) == f"Delta log not found for table version: {next_version}":
+                    next_version += 1
+                else:
+                    raise
+        return None, version
+
     def create_checkpoint(self) -> None:
         self._table.create_checkpoint()
 

python/src/lib.rs

@@ -43,7 +43,7 @@ use deltalake::DeltaOps;
 use deltalake::DeltaTableBuilder;
 use pyo3::exceptions::{PyIOError, PyRuntimeError, PyValueError};
 use pyo3::prelude::*;
-use pyo3::types::{PyFrozenSet, PyType};
+use pyo3::types::{PyBytes, PyFrozenSet, PyType};
 use serde_json::{Map, Value};
 
 use crate::error::DeltaProtocolError;
@@ -154,6 +154,13 @@ impl RawDeltaTable {
         Ok(self._table.version())
     }
 
+    pub fn get_obj<'py>(&self, py: Python<'py>, version: i64) -> PyResult<&'py PyBytes> {
+        let commit_log_bytes = rt()?
+            .block_on(self._table.get_obj_from_version(version))
+            .map_err(PythonError::from)?;
+        return Ok(PyBytes::new(py, &commit_log_bytes));
+    }
+
     pub fn metadata(&self) -> PyResult<RawDeltaTableMetaData> {
         let metadata = self._table.metadata().map_err(PythonError::from)?;
         Ok(RawDeltaTableMetaData {

python/tests/test_table_read.py

@@ -493,6 +493,29 @@ def test_writer_fails_on_protocol():
         dt.to_pandas()
 
 
+@pytest.mark.parametrize("version, expected", [(2, (5, 3))])
+def test_peek_next_commit(version, expected):
+    table_path = "../crates/deltalake-core/tests/data/simple_table"
+    dt = DeltaTable(table_path)
+    actions, next_version = dt.peek_next_commit(version=version)
+    assert (len(actions), next_version) == expected
+
+
+def test_delta_log_not_found():
+    table_path = "../crates/deltalake-core/tests/data/simple_table"
+    dt = DeltaTable(table_path)
+    latest_version = dt.get_latest_version()
+    _, version = dt.peek_next_commit(version=latest_version)
+    assert version == latest_version
+
+
+def test_delta_log_missed():
+    table_path = "../crates/deltalake-core/tests/data/simple_table_missing_commit"
+    dt = DeltaTable(table_path)
+    _, version = dt.peek_next_commit(version=1)
+    assert version == 3  # Missed commit version 2, should return version 3
+
+
 class ExcPassThroughThread(Thread):
     """Wrapper around `threading.Thread` that propagates exceptions."""