[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15970657#comment-15970657
]
Wes McKinney commented on ARROW-809:
PR (WIP): https://github.com/apache/arrow/pull/555
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Assignee: Wes McKinney
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968317#comment-15968317
]
Itai Incze commented on ARROW-809:
--
I wrote the comment before seeing yours latest one, so not in order to doubt
the solution.
I've seen that code... though I'm certain you're much better acquainted with
it than I am :)
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Assignee: Wes McKinney
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
--
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968310#comment-15968310
]
Wes McKinney commented on ARROW-809:
There is some buffer slicing happening on the IPC write path already:
https://github.com/apache/arrow/blob/master/cpp/src/arrow/ipc/writer.cc#L207.
It needs to be made consistent (+ well tested), though
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Assignee: Wes McKinney
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
--
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968295#comment-15968295
]
Itai Incze commented on ARROW-809:
--
I've fiddled with it a bit - without altering the array class, I found there's
a problem finding the exact number of items with a boolean array - where it
doesnt matter, and in union array. There may be other instances as well that
i'm not aware of.
Seems to me that adding a private boolean {{IsSliced}} to the array is the
cleanest way.
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Assignee: Wes McKinney
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
--
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968289#comment-15968289
]
Itai Incze commented on ARROW-809:
--
Agreed - its a small and easy bug. All is needed is to agree on the approach.
I've fiddled with it a bit - without altering the array class, I found there's
a problem finding the exact number of items with a boolean array - where it
doesnt matter, and in union array. There may be other instances as well that
i'm not aware of.
Seems to me that adding a private boolean {{IsSliced}} to the array is the
cleanest way.
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Assignee: Wes McKinney
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
--
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968285#comment-15968285
]
Wes McKinney commented on ARROW-809:
I'm going to truncate the data buffers to a 64-byte padding offset, patch
coming tomorrow probably
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Assignee: Wes McKinney
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
--
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968010#comment-15968010
]
Wes McKinney commented on ARROW-809:
Marked for 0.3. I don't think this should be hard to fix
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Priority: Minor
> Fix For: 0.3.0
>
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t2.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
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[jira] [Commented] (ARROW-809) C++: Writing sliced record batch to IPC writes the entire array
[
https://issues.apache.org/jira/browse/ARROW-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15965731#comment-15965731
]
Itai Incze commented on ARROW-809:
--
The reason for the bug seems to be that sliced arrays are tested with the
condition {{(array.offset() != 0)}} throughout {{arrow/ipc/writer.cc}}, which
doesn't account for a {{\[0:x\]}} slice.
To test for 0-based slices there's a need to know the number of elements in the
original array, which is easily computed in cases like fixed-width array types
but could be harder in others.
Another approach could be adding a class member to mark the slices. This could
be either by a simple boolean, the original dimensions or a reference to the
original array.
> C++: Writing sliced record batch to IPC writes the entire array
> ---
>
> Key: ARROW-809
> URL: https://issues.apache.org/jira/browse/ARROW-809
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
>Reporter: Itai Incze
>Priority: Minor
>
> The bug can be triggered through python:
> {code}
> import pyarrow.parquet
> array = pyarrow.array.from_pylist([1] * 100)
> rb = pyarrow.RecordBatch.from_arrays([array], ['a'])
> rb2 = rb.slice(0,2)
> with open('/tmp/t.arrow', 'wb') as f:
> w = pyarrow.ipc.FileWriter(f, rb.schema)
> w.write_batch(rb2)
> w.close()
> {code}
> which will result in a big file:
> {code}
> $ ll /tmp/t2.arrow
> -rw-rw-r-- 1 itai itai 800618 Apr 12 13:22 /tmp/t.arrow
> {code}
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