[Data] Soft deprecate prefetch_blocks parameter of iter_rows

python/ray/data/dataset.py

@@ -3623,7 +3623,9 @@ def iterator(self) -> DataIterator:
         return DataIteratorImpl(self)
 
     @ConsumptionAPI
-    def iter_rows(self, *, prefetch_blocks: int = 0) -> Iterable[Dict[str, Any]]:
+    def iter_rows(
+        self, *, prefetch_batches: int = 0, prefetch_blocks: int = 0
+    ) -> Iterable[Dict[str, Any]]:
         """Return an iterable over the rows in this dataset.
 
         Examples:
@@ -3637,13 +3639,17 @@ def iter_rows(self, *, prefetch_blocks: int = 0) -> Iterable[Dict[str, Any]]:
         Time complexity: O(1)
 
         Args:
-            prefetch_blocks: The number of blocks to prefetch ahead of the
-                current block during the scan.
+            prefetch_batches: The number of batches to prefetch ahead of the current
+                batch during the scan.
+            prefetch_blocks: This argument is deprecated. Use ``prefetch_batches``
+                instead.
 
         Returns:
             An iterable over the rows in this dataset.
         """
-        return self.iterator().iter_rows(prefetch_blocks=prefetch_blocks)
+        return self.iterator().iter_rows(
+            prefetch_batches=prefetch_batches, prefetch_blocks=prefetch_blocks
+        )
 
     @ConsumptionAPI
     def iter_batches(

python/ray/data/iterator.py

@@ -1,5 +1,6 @@
 import abc
 import time
+import warnings
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -204,7 +205,9 @@ def _create_iterator() -> Iterator[DataBatch]:
     def _get_dataset_tag(self) -> str:
         return "unknown_dataset"
 
-    def iter_rows(self, *, prefetch_blocks: int = 0) -> Iterable[Dict[str, Any]]:
+    def iter_rows(
+        self, *, prefetch_batches: int = 0, prefetch_blocks: int = 0
+    ) -> Iterable[Dict[str, Any]]:
         """Return a local row iterable over the dataset.
 
         If the dataset is a tabular dataset (Arrow/Pandas blocks), dicts
@@ -220,15 +223,27 @@ def iter_rows(self, *, prefetch_blocks: int = 0) -> Iterable[Dict[str, Any]]:
         Time complexity: O(1)
 
         Args:
-            prefetch_blocks: The number of blocks to prefetch ahead of the
-                current block during the scan.
+            prefetch_batches: The number of batches to prefetch ahead of the current
+                batch during the scan.
+            prefetch_blocks: This argument is deprecated. Use ``prefetch_batches``
+                instead.
 
         Returns:
             An iterable over rows of the dataset.
         """
-        iter_batch_args = {"batch_size": None, "batch_format": None}
-
-        iter_batch_args["prefetch_batches"] = prefetch_blocks
+        iter_batch_args = {
+            "batch_size": None,
+            "batch_format": None,
+            "prefetch_batches": prefetch_batches,
+        }
+        if prefetch_blocks > 0:
+            warnings.warn(
+                "`prefetch_blocks` is deprecated in Ray 2.10. Use "
+                "the `prefetch_batches` parameter to specify the amount of prefetching "
+                "in terms of batches instead of blocks.",
+                DeprecationWarning,
+            )
+            iter_batch_args["prefetch_batches"] = prefetch_blocks
 
         batch_iterable = self.iter_batches(**iter_batch_args)
 

python/ray/data/tests/test_consumption.py

@@ -715,7 +715,7 @@ def to_pylist(table):
         assert row == df_row.to_dict()
 
     # Prefetch.
-    for row, t_row in zip(ds.iter_rows(prefetch_blocks=1), to_pylist(t)):
+    for row, t_row in zip(ds.iter_rows(prefetch_batches=1), to_pylist(t)):
         assert isinstance(row, dict)
         assert row == t_row