westonpace commented on issue #35305:
URL: https://github.com/apache/arrow/issues/35305#issuecomment-1527954990
I think we might need more details or a reproducing script of some kind.
Here is a quick experiment I ran:
```
import pyarrow as pa
import pyarrow.compute as pc
import pyarrow.parquet as pq
import pyarrow.dataset as ds
import shutil
shutil.rmtree("/tmp/my_dataset", ignore_errors=True)
values = list(range(100))
int_col = pa.array(values, pa.int64())
ts_col = pc.cast(int_col, pa.timestamp('us'))
table = pa.Table.from_arrays([int_col, ts_col], names=["ints","timestamps"])
ds.write_dataset(table, "/tmp/my_dataset", format="parquet")
my_dataset = ds.dataset("/tmp/my_dataset")
# Prime the query once to load parquet metadata into memory
my_dataset.to_table()
big_ts = pc.cast(pa.array([1000], pa.int64()), pa.timestamp('us'))[0]
print("WITH FILTER")
print(my_dataset.to_table(filter=pc.field("timestamps") > big_ts))
print("WITHOUT FILTER")
print(my_dataset.to_table())
```
I then tested this with `strace` using the command `strace -f -P
/tmp/my_dataset/part-0.parquet python repr.py`:
```
WITH FILTER
pyarrow.Table
ints: int64
timestamps: timestamp[us]
----
ints: [[]]
timestamps: [[]]
WITHOUT FILTER
[pid 43296] openat(AT_FDCWD, "/tmp/my_dataset/part-0.parquet", O_RDONLY) = 7
[pid 43296] newfstatat(7, "", {st_mode=S_IFREG|0664, st_size=2111, ...},
AT_EMPTY_PATH) = 0
[pid 43296] newfstatat(7, "", {st_mode=S_IFREG|0664, st_size=2111, ...},
AT_EMPTY_PATH) = 0
[pid 43314] pread64(7,
"\25\4\25\300\f\25\266\6L\25\310\1\25\4\22\0\0\240\6\0\0\r\1\0\1\r\10\0\2\r\10\0"...,
595, 4) = 595
[pid 43314] pread64(7,
"\25\4\25\300\f\25\266\6L\25\310\1\25\4\22\0\0\240\6\0\0\r\1\0\1\r\10\0\2\r\10\0"...,
595, 695) = 595
[pid 43314] close(7) = 0
pyarrow.Table
ints: int64
timestamps: timestamp[us]
----
ints: [[0,1,2,3,4,...,95,96,97,98,99]]
timestamps: [[1970-01-01 00:00:00.000000,1970-01-01
00:00:00.000001,1970-01-01 00:00:00.000002,1970-01-01
00:00:00.000003,1970-01-01 00:00:00.000004,...,1970-01-01
00:00:00.000095,1970-01-01 00:00:00.000096,1970-01-01
00:00:00.000097,1970-01-01 00:00:00.000098,1970-01-01 00:00:00.000099]]
```
I also verified with a debugger that the row groups are not actually being
read.
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