[GitHub] [arrow] wjones1 commented on a change in pull request #6979: ARROW-7800 [Python] implement iter_batches() method for ParquetFile and ParquetReader

[GitBox <gi...@apache.org>]

wjones1 commented on a change in pull request #6979:
URL: https://github.com/apache/arrow/pull/6979#discussion_r446469923



##########
File path: python/pyarrow/parquet.py
##########
@@ -310,6 +310,44 @@ def read_row_groups(self, row_groups, columns=None, use_threads=True,
                                            column_indices=column_indices,
                                            use_threads=use_threads)
 
+    def iter_batches(self, batch_size, row_groups=None, columns=None,

Review comment:
       Agreed. I added the same default value for `iter_batches()`

##########
File path: python/pyarrow/_parquet.pyx
##########
@@ -1077,6 +1078,54 @@ cdef class ParquetReader:
     def set_use_threads(self, bint use_threads):
         self.reader.get().set_use_threads(use_threads)
 
+    def set_batch_size(self, int64_t batch_size):
+        self.reader.get().set_batch_size(batch_size)
+
+    def iter_batches(self, int64_t batch_size, row_groups, column_indices=None,
+                     bint use_threads=True):
+        cdef:
+            vector[int] c_row_groups
+            vector[int] c_column_indices
+            shared_ptr[CRecordBatch] record_batch
+            shared_ptr[TableBatchReader] batch_reader
+            unique_ptr[CRecordBatchReader] recordbatchreader
+
+        self.set_batch_size(batch_size)
+
+        if use_threads:
+            self.set_use_threads(use_threads)
+
+        for row_group in row_groups:
+            c_row_groups.push_back(row_group)
+
+        if column_indices is not None:
+            for index in column_indices:
+                c_column_indices.push_back(index)
+            check_status(
+                self.reader.get().GetRecordBatchReader(
+                    c_row_groups, c_column_indices, &recordbatchreader
+                )
+            )
+        else:
+            check_status(
+                self.reader.get().GetRecordBatchReader(
+                    c_row_groups, &recordbatchreader
+                )
+            )
+
+        while True:
+            with nogil:
+                check_status(
+                    recordbatchreader.get().ReadNext(&record_batch)
+                )
+
+            if record_batch.get() == NULL:
+                break
+
+            py_record_batch = pyarrow_wrap_batch(record_batch)

Review comment:
       👍 




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