This is an automated email from the ASF dual-hosted git repository.
JingsongLi pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/paimon-mosaic.git
The following commit(s) were added to refs/heads/main by this push:
new 09908ca fix: preserve empty projection in read_table (#25)
09908ca is described below
commit 09908ca29c0da12e553d55d6cd7688be9c682505
Author: QuakeWang <[email protected]>
AuthorDate: Thu May 21 12:52:58 2026 +0800
fix: preserve empty projection in read_table (#25)
---
python/mosaic/mosaic.py | 2 +-
python/tests/test_mosaic.py | 22 ++++++++++++++++++++++
2 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/python/mosaic/mosaic.py b/python/mosaic/mosaic.py
index ab759de..91c62ac 100644
--- a/python/mosaic/mosaic.py
+++ b/python/mosaic/mosaic.py
@@ -411,6 +411,6 @@ def write_table(table, stream, options=None):
def read_table(read_at_fn, file_length, columns=None):
with MosaicReader.from_input_file(read_at_fn, file_length) as reader:
- if columns:
+ if columns is not None:
reader.project(columns)
return reader.read_all()
diff --git a/python/tests/test_mosaic.py b/python/tests/test_mosaic.py
index b60f0f1..a333ea4 100644
--- a/python/tests/test_mosaic.py
+++ b/python/tests/test_mosaic.py
@@ -657,6 +657,28 @@ class TestConvenience:
assert result.column("id").to_pylist() == list(range(30))
assert result.column("name").to_pylist() == [f"user_{i}" for i in
range(30)]
+ def test_read_table_empty_projection(self):
+ table = pa.table(
+ {
+ "id": pa.array(list(range(30)), type=pa.int32()),
+ "name": pa.array([f"user_{i}" for i in range(30)]),
+ }
+ )
+
+ buf = io.BytesIO()
+ write_table(table, buf)
+
+ data = buf.getvalue()
+ result = read_table(
+ lambda offset, length: data[offset : offset + length],
+ len(data),
+ columns=[],
+ )
+
+ assert result.num_columns == 0
+ assert result.num_rows == 30
+ assert result.schema.names == []
+
def test_read_all(self):
pa_schema = pa.schema(
[pa.field("x", pa.int32()), pa.field("y", pa.utf8())]
