overwrite partitions

daft/dataframe/dataframe.py

@@ -552,7 +552,7 @@ def write_parquet(
         self,
         root_dir: Union[str, pathlib.Path],
         compression: str = "snappy",
-        write_mode: Literal["append", "overwrite"] = "append",
+        write_mode: Literal["append", "overwrite", "overwrite-partitions"] = "append",
         partition_cols: Optional[List[ColumnInputType]] = None,
         io_config: Optional[IOConfig] = None,
     ) -> "DataFrame":
@@ -566,7 +566,7 @@ def write_parquet(
         Args:
             root_dir (str): root file path to write parquet files to.
             compression (str, optional): compression algorithm. Defaults to "snappy".
-            write_mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace table with new data. Defaults to "append".
+            write_mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace table with new data. `overwrite-partitions` will overwrite only the partitions that are being written. Defaults to "append".
             partition_cols (Optional[List[ColumnInputType]], optional): How to subpartition each partition further. Defaults to None.
             io_config (Optional[IOConfig], optional): configurations to use when interacting with remote storage.
 
@@ -576,8 +576,12 @@ def write_parquet(
             .. NOTE::
                 This call is **blocking** and will execute the DataFrame when called
         """
-        if write_mode not in ["append", "overwrite"]:
-            raise ValueError(f"Only support `append` or `overwrite` mode. {write_mode} is unsupported")
+        if write_mode not in ["append", "overwrite", "overwrite-partitions"]:
+            raise ValueError(
+                f"Only support `append`, `overwrite`, or `overwrite-partitions` mode. {write_mode} is unsupported"
+            )
+        if write_mode == "overwrite-partitions" and partition_cols is None:
+            raise ValueError("Partition columns must be specified to use `overwrite-partitions` mode.")
 
         io_config = get_context().daft_planning_config.default_io_config if io_config is None else io_config
 
@@ -598,7 +602,9 @@ def write_parquet(
         assert write_df._result is not None
 
         if write_mode == "overwrite":
-            overwrite_files(write_df, root_dir, io_config)
+            overwrite_files(write_df, root_dir, io_config, False)
+        elif write_mode == "overwrite-partitions":
+            overwrite_files(write_df, root_dir, io_config, True)
 
         if len(write_df) > 0:
             # Populate and return a new disconnected DataFrame
@@ -624,7 +630,7 @@ def write_parquet(
     def write_csv(
         self,
         root_dir: Union[str, pathlib.Path],
-        write_mode: Literal["append", "overwrite"] = "append",
+        write_mode: Literal["append", "overwrite", "overwrite-partitions"] = "append",
         partition_cols: Optional[List[ColumnInputType]] = None,
         io_config: Optional[IOConfig] = None,
     ) -> "DataFrame":
@@ -637,15 +643,19 @@ def write_csv(
 
         Args:
             root_dir (str): root file path to write parquet files to.
-            write_mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace table with new data. Defaults to "append".
+            write_mode (str, optional): Operation mode of the write. `append` will add new data, `overwrite` will replace table with new data. `overwrite-partitions` will overwrite only the partitions that are being written. Defaults to "append".
             partition_cols (Optional[List[ColumnInputType]], optional): How to subpartition each partition further. Defaults to None.
             io_config (Optional[IOConfig], optional): configurations to use when interacting with remote storage.
 
         Returns:
             DataFrame: The filenames that were written out as strings.
         """
-        if write_mode not in ["append", "overwrite"]:
-            raise ValueError(f"Only support `append` or `overwrite` mode. {write_mode} is unsupported")
+        if write_mode not in ["append", "overwrite", "overwrite-partitions"]:
+            raise ValueError(
+                f"Only support `append`, `overwrite`, or `overwrite-partitions` mode. {write_mode} is unsupported"
+            )
+        if write_mode == "overwrite-partitions" and partition_cols is None:
+            raise ValueError("Partition columns must be specified to use `overwrite-partitions` mode.")
 
         io_config = get_context().daft_planning_config.default_io_config if io_config is None else io_config
 
@@ -665,7 +675,9 @@ def write_csv(
         assert write_df._result is not None
 
         if write_mode == "overwrite":
-            overwrite_files(write_df, root_dir, io_config)
+            overwrite_files(write_df, root_dir, io_config, False)
+        elif write_mode == "overwrite-partitions":
+            overwrite_files(write_df, root_dir, io_config, True)
 
         if len(write_df) > 0:
             # Populate and return a new disconnected DataFrame

daft/filesystem.py

@@ -11,6 +11,7 @@
 
 from daft.convert import from_pydict
 from daft.daft import FileFormat, FileInfos, IOConfig, io_glob
+from daft.datatype import DataType
 from daft.dependencies import fsspec, pafs
 from daft.expressions.expressions import col, lit
 from daft.table import MicroPartition
@@ -368,6 +369,7 @@ def overwrite_files(
     manifest: DataFrame,
     root_dir: str | pathlib.Path,
     io_config: IOConfig | None,
+    overwrite_partitions: bool,
 ) -> None:
     [resolved_path], fs = _resolve_paths_and_filesystem(root_dir, io_config=io_config)
     file_selector = pafs.FileSelector(resolved_path, recursive=True)
@@ -376,12 +378,26 @@ def overwrite_files(
     except FileNotFoundError:
         # The root directory does not exist, so there are no files to delete.
         return
-
     all_file_paths_df = from_pydict({"path": paths})
 
     assert manifest._result is not None
     written_file_paths = manifest._result._get_merged_micropartition().get_column("path")
-    to_delete = all_file_paths_df.where(~(col("path").is_in(lit(written_file_paths))))
+    if overwrite_partitions:
+        # Extract directories of written files
+        written_dirs = set(str(pathlib.Path(path).parent) for path in written_file_paths.to_pylist())
+
+        # Filter existing files to only those in directories where we wrote new files
+        to_delete = all_file_paths_df.where(
+            (~(col("path").is_in(lit(written_file_paths))))
+            & (
+                col("path")
+                .apply(lambda x: str(pathlib.Path(x).parent), return_dtype=DataType.string())
+                .is_in(list(written_dirs))
+            )
+        )
+    else:
+        # If we are not overwriting partitions, we only want to delete files that were written
+        to_delete = all_file_paths_df.where(~(col("path").is_in(lit(written_file_paths))))
 
     # TODO: Look into parallelizing this
     for entry in to_delete: