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[C++] Possibly an unnecessary copy when outputting join result batch #35124

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zanmato1984 opened this issue Apr 14, 2023 · 0 comments · Fixed by #35114
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[C++] Possibly an unnecessary copy when outputting join result batch #35124

zanmato1984 opened this issue Apr 14, 2023 · 0 comments · Fixed by #35114
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@zanmato1984
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Component: C++ Type: enhancement
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13.0.0

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@zanmato1984
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zanmato1984 commented Apr 14, 2023 •
edited

Describe the enhancement requested

See this line:

arrow/cpp/src/arrow/acero/swiss_join_internal.h

Line 571 in 913c345

ARROW_RETURN_NOT_OK(output_batch_fn(batch));

According to the email discussion with @save-buffer :

I think the compiler will automatically emit the move because it sees we’re copying from an object that’ll never be used again [1], but adding the std::move would be good just to remove any ambiguity.

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@github-actions github-actions bot mentioned this issue Apr 14, 2023
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westonpace pushed a commit that referenced this issue Apr 18, 2023
@zanmato1984
GH-35124: [C++] Avoid unnecessary copy when outputting join result (#…
a2548a7 
…35114)

### Rationale for this change

Seems this https://github.com/apache/arrow/blob/913c34506000fd77444ea7b7f24dcb6402003d6b/cpp/src/arrow/acero/swiss_join_internal.h#L571 is an unnecessary copy when outputting join result batch. According to Sasha K.:

> I _think_ the compiler will automatically emit the move because it sees we’re copying from an object that’ll never be used again [1], but adding the std::move would be good just to remove any ambiguity.

### What changes are included in this PR?

Adding `std::move()` to disambiguate/eliminate the unnecessary copy.

### Are these changes tested?

No. This change is possibly undetectable, and the existing tests should cover it well.

### Are there any user-facing changes?

No.

* Closes: #35124

Authored-by: zanmato1984 <zanmato1984@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>
@westonpace westonpace added this to the 13.0.0 milestone Apr 18, 2023
liujiacheng777 pushed a commit to LoongArch-Python/arrow that referenced this issue May 11, 2023
@zanmato1984 @liujiacheng777
apacheGH-35124: [C++] Avoid unnecessary copy when outputting join res…
a2356fd 
…ult (apache#35114)

### Rationale for this change

Seems this https://github.com/apache/arrow/blob/913c34506000fd77444ea7b7f24dcb6402003d6b/cpp/src/arrow/acero/swiss_join_internal.h#L571 is an unnecessary copy when outputting join result batch. According to Sasha K.:

> I _think_ the compiler will automatically emit the move because it sees we’re copying from an object that’ll never be used again [1], but adding the std::move would be good just to remove any ambiguity.

### What changes are included in this PR?

Adding `std::move()` to disambiguate/eliminate the unnecessary copy.

### Are these changes tested?

No. This change is possibly undetectable, and the existing tests should cover it well.

### Are there any user-facing changes?

No.

* Closes: apache#35124

Authored-by: zanmato1984 <zanmato1984@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>
ArgusLi pushed a commit to Bit-Quill/arrow that referenced this issue May 15, 2023
@zanmato1984 @ArgusLi
apacheGH-35124: [C++] Avoid unnecessary copy when outputting join res…
8ff44b9 
…ult (apache#35114)

### Rationale for this change

Seems this https://github.com/apache/arrow/blob/913c34506000fd77444ea7b7f24dcb6402003d6b/cpp/src/arrow/acero/swiss_join_internal.h#L571 is an unnecessary copy when outputting join result batch. According to Sasha K.:

> I _think_ the compiler will automatically emit the move because it sees we’re copying from an object that’ll never be used again [1], but adding the std::move would be good just to remove any ambiguity.

### What changes are included in this PR?

Adding `std::move()` to disambiguate/eliminate the unnecessary copy.

### Are these changes tested?

No. This change is possibly undetectable, and the existing tests should cover it well.

### Are there any user-facing changes?

No.

* Closes: apache#35124

Authored-by: zanmato1984 <zanmato1984@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>
rtpsw pushed a commit to rtpsw/arrow that referenced this issue May 16, 2023
@zanmato1984 @rtpsw
apacheGH-35124: [C++] Avoid unnecessary copy when outputting join res…
202bdea 
…ult (apache#35114)

### Rationale for this change

Seems this https://github.com/apache/arrow/blob/913c34506000fd77444ea7b7f24dcb6402003d6b/cpp/src/arrow/acero/swiss_join_internal.h#L571 is an unnecessary copy when outputting join result batch. According to Sasha K.:

> I _think_ the compiler will automatically emit the move because it sees we’re copying from an object that’ll never be used again [1], but adding the std::move would be good just to remove any ambiguity.

### What changes are included in this PR?

Adding `std::move()` to disambiguate/eliminate the unnecessary copy.

### Are these changes tested?

No. This change is possibly undetectable, and the existing tests should cover it well.

### Are there any user-facing changes?

No.

* Closes: apache#35124

Authored-by: zanmato1984 <zanmato1984@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>
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GH-35124: [C++] Avoid unnecessary copy when outputting join result zanmato1984/arrow
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