GH-46531: [C++] Add type_singleton utility function and tests. by harshkumar-2005 · Pull Request #47922 · apache/arrow

harshkumar-2005 · 2025-10-23T14:55:50Z

Rationale for this change

Introduce a type_singleton(Type::type id) utility to create parameter-free DataType instances (such as int32, boolean, utf8, etc.). Returns an error for parameterized types.

Are these changes tested?

Yes, by additional unit tests in type_test.cc.

Are there any user-facing changes?

No.

GitHub Issue: [C++] Add a type_singleton utility function #46531

github-actions · 2025-10-23T14:56:22Z

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

harshkumar-2005 · 2025-10-24T05:02:39Z

@pitrou Cl jobs are awaiting maintainer approval. Please approve to trigger the remaining checks.

harshkumar-2005 · 2025-10-25T05:57:17Z

@pitrou
This PR has 9 workflows pending approval. Kindly review and approve to initiate the workflow runs. Thank you!

github-actions · 2025-10-26T07:39:03Z

⚠️ GitHub issue #46531 has been automatically assigned in GitHub to PR creator.

pitrou

Thanks for doing this @harshkumar-2005 . Please find a couple comments below.

pitrou · 2026-02-03T14:01:14Z

@harshkumar-2005 Are you using AI for this PR?

pitrou · 2026-02-03T13:58:35Z

+
+TEST(TestTypeSingleton, ParameterizedTypes) {
+  // Test error cases - parameterized types
+  std::vector<Type::type> parameterized_types = {


Same comment here: no need to test these exhaustively, only one of them will be enough.

pitrou · 2026-02-03T13:59:33Z

+#include "arrow/type.h"
 #include "arrow/util/logging_internal.h"

-namespace arrow {


Why this change?

You still forgot to undo this.

pitrou · 2026-02-03T14:00:42Z

+
+  Visitor visitor;
+  auto status = VisitTypeIdInline(id, &visitor);
+  if (!status.ok()) {


No need for this as the visitor is already returning a Status.

harshkumar-2005 · 2026-02-03T14:06:45Z

@harshkumar-2005 Are you using AI for this PR?

Yes, partially—for understanding a few concepts. The implementation and final code are mine.

pitrou · 2026-02-03T14:08:32Z

@harshkumar-2005 Are you using AI for this PR?

Yes, partially—for understanding a few concepts. The implementation and final code are mine.

Ok, thanks. I was asking because your latest changes seemed unfinished and don't compile at all on CI.

pitrou

@harshkumar-2005 Here are a couple more suggestions. Also, please review and build your own code before submitting, as some changes probably break compilation.

pitrou · 2026-02-05T14:03:22Z

+    ASSERT_TRUE(type->Equals(*test_case.second))
+        << "Failed on type " << test_case.first << ". Expected "
+        << test_case.second->ToString() << " but got " << type->ToString();


Suggested improvement: you can use AssertTypeEqual to automate the generation of a nice error message if the types don't match.

pitrou · 2026-02-05T14:04:15Z

+              testing::HasSubstr("is not a parameter-free singleton type"));
+}
+
+TEST(TestTypeSingleton, InvalidType) {


I don't think this test is useful, passing an invalid type id is a programming error.

pitrou · 2026-02-05T14:05:54Z

 #include "arrow/type_traits.h"
 #include "arrow/util/checked_cast.h"
 #include "arrow/util/key_value_metadata.h"
+#include "arrow/util/logging.h"


This include doesn't seem actually used?

pitrou · 2026-02-05T14:06:16Z

+#include "arrow/type.h"
 #include "arrow/util/logging_internal.h"

-namespace arrow {


You still forgot to undo this.

pitrou · 2026-02-05T14:06:33Z


 #include "arrow/type_traits.h"
-
+#include "arrow/type.h"


Not sure why this addition is required?

pitrou · 2026-02-05T14:06:45Z

 #include <type_traits>
 #include <vector>

+#include "arrow/result.h"


Why these additions? Let's remove them.

github-actions · 2026-02-18T14:54:48Z

⚠️ GitHub issue #46531 has been automatically assigned in GitHub to PR creator.

github-actions · 2026-02-18T14:55:48Z

⚠️ GitHub issue #46531 has been automatically assigned in GitHub to PR creator.

…ing tests

pitrou · 2026-02-18T15:04:36Z

I've pushed some updates to fix compilation and simplify the implementation. Will merge if green.

conbench-apache-arrow · 2026-02-19T03:48:18Z

After merging your PR, Conbench analyzed the 1 benchmarking run that has been run so far on merge-commit 99984fd.

There was 1 benchmark result indicating a performance regression:

Commit Run on arm64-t4g-2xlarge-linux at 2026-02-19 01:58:22Z
- dataset-select (Python) with dataset=nyctaxi_multi_parquet_s3_repartitioned

The full Conbench report has more details. It also includes information about 37 possible false positives for unstable benchmarks that are known to sometimes produce them.

conbench-apache-arrow · 2026-02-21T10:04:25Z

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit 99984fd.

There were 3 benchmark results indicating a performance regression:

Commit Run on amd64-m5-4xlarge-linux at 2026-02-21 07:33:59Z
- file-read (Python) with compression=uncompressed, dataset=nyctaxi_2010-01, file_type=feather, output_type=table
- file-read (Python) with compression=uncompressed, dataset=fanniemae_2016Q4, file_type=feather, output_type=dataframe
and 1 more (see the report linked below)

The full Conbench report has more details. It also includes information about 14 possible false positives for unstable benchmarks that are known to sometimes produce them.

harshkumar-2005 · 2026-02-22T14:04:31Z

Thanks for the merge! I noticed the performance alerts on both the ARM and Intel runners for file-read. I'm setting up some local benchmarks to verify this. Before I go too deep into the profiling, I’m curious if these Python benchmarks are known to be sensitive to the recent changes in [mention a related area, e.g., memory management/IPC]. Any thoughts on whether this looks like genuine regression vs. environment noise would be highly valued.

pitrou · 2026-02-23T08:44:14Z

Hi @harshkumar-2005 , those performance alerts are certainly false positives since we haven't touched any performance-sensitive codepaths. You probably needn't bother.

…pache#47922) ### Rationale for this change Introduce a `type_singleton(Type::type id)` utility to create parameter-free DataType instances (such as int32, boolean, utf8, etc.). Returns an error for parameterized types. ### Are these changes tested? Yes, by additional unit tests in `type_test.cc`. ### Are there any user-facing changes? No. * GitHub Issue: apache#46531 Authored-by: Harsh <kumarharsh93982@gmail.com> Signed-off-by: Antoine Pitrou <antoine@python.org>

github-actions Bot added Component: C++ awaiting review Awaiting review labels Oct 23, 2025

harshkumar-2005 changed the title ~~ARROW-46531: [C++] Add type_singleton utility function and tests~~ GH-46531: [C++] Add type_singleton utility function and tests GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY} Oct 26, 2025

harshkumar-2005 changed the title ~~GH-46531: [C++] Add type_singleton utility function and tests GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}~~ GH-46531: [C++] Add type_singleton utility function and tests. Oct 26, 2025

pitrou requested changes Feb 3, 2026

View reviewed changes

Comment thread cpp/src/arrow/type_traits.cc Outdated

Comment thread cpp/src/arrow/type_traits.cc Outdated

Comment thread cpp/src/arrow/type_test.cc

Comment thread cpp/src/arrow/type_traits.h Outdated

github-actions Bot added awaiting review Awaiting review awaiting committer review Awaiting committer review and removed awaiting review Awaiting review labels Feb 3, 2026

harshkumar-2005 force-pushed the ARROW-46531-type-singleton-util branch from a171977 to 98795b2 Compare February 3, 2026 13:23

github-actions Bot added awaiting review Awaiting review and removed awaiting review Awaiting review awaiting committer review Awaiting committer review labels Feb 3, 2026

pitrou requested changes Feb 3, 2026

View reviewed changes

github-actions Bot added awaiting committer review Awaiting committer review and removed awaiting review Awaiting review labels Feb 3, 2026

harshkumar-2005 requested a review from pitrou February 4, 2026 16:39

pitrou requested changes Feb 5, 2026

View reviewed changes

harshkumar-2005 requested a review from pitrou February 5, 2026 15:34

pitrou force-pushed the ARROW-46531-type-singleton-util branch from a10dfb1 to 4bb9a23 Compare February 18, 2026 14:55

ARROW-46531: [C++] Add type_singleton utility function and correspond…

0a87cce

…ing tests

pitrou force-pushed the ARROW-46531-type-singleton-util branch from 4bb9a23 to 0a87cce Compare February 18, 2026 14:56

pitrou approved these changes Feb 18, 2026

View reviewed changes

pitrou merged commit 99984fd into apache:main Feb 18, 2026
55 checks passed

pitrou removed the awaiting committer review Awaiting committer review label Feb 18, 2026

pitrou mentioned this pull request Feb 18, 2026

[C++] Add a type_singleton utility function #46531

Closed

harshkumar-2005 deleted the ARROW-46531-type-singleton-util branch February 18, 2026 18:55

Uh oh!

Conversation

harshkumar-2005 commented Oct 23, 2025 • edited by pitrou Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Rationale for this change

Are these changes tested?

Are there any user-facing changes?

Uh oh!

github-actions Bot commented Oct 23, 2025

Uh oh!

harshkumar-2005 commented Oct 24, 2025

Uh oh!

harshkumar-2005 commented Oct 25, 2025

Uh oh!

github-actions Bot commented Oct 26, 2025

Uh oh!

pitrou left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

pitrou commented Feb 3, 2026

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

harshkumar-2005 commented Feb 3, 2026

Uh oh!

pitrou commented Feb 3, 2026

Uh oh!

pitrou left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

github-actions Bot commented Feb 18, 2026

Uh oh!

github-actions Bot commented Feb 18, 2026

Uh oh!

pitrou commented Feb 18, 2026

Uh oh!

Uh oh!

conbench-apache-arrow Bot commented Feb 19, 2026

Uh oh!

conbench-apache-arrow Bot commented Feb 21, 2026

Uh oh!

harshkumar-2005 commented Feb 22, 2026

Uh oh!

pitrou commented Feb 23, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

harshkumar-2005 commented Oct 23, 2025 •

edited by pitrou

Loading