Expose option to set line terminator for CSV writer by svranesevic · Pull Request #9617 · apache/arrow-rs

svranesevic · 2026-03-26T09:19:54Z

Which issue does this PR close?

Closes Allow setting custom line terminator for CSV writer #9571.

Rationale for this change

Enable configuring line terminator for CSV writer.

What changes are included in this PR?

See above.

Are these changes tested?

Yes, added tests.

Are there any user-facing changes?

Yes, expose option to set line terminator for CSV writer.

alamb

Looks good to me -- thank you @svranesevic

I have one request to reduce the size of this PR by reducing redundany in the tests, but otherwise I think this one is ready to go

alamb · 2026-03-27T21:17:18Z

+    }
+
+    #[test]
+    fn test_write_csv_with_lf_terminator() {


these tests are quite repetitive (they are like 20 lines long but the only difference is 2 lines -- the terminaor and the expected output)

Can you please refactor them into a common harness so that it is easier for (me, a human) to review them and ensure coverage is adequate?

Thank you

I am trying to clear up the PR review queue, so I took the liberty of pushing a commit that reduces the test replication and merged up from main

Thank you! Is there anything else for me to take care of?

nope -- this looks good

…_line_terminator

alamb · 2026-04-01T12:44:11Z

run benchmarks csv_writer

adriangbot · 2026-04-01T12:46:34Z

🤖 Arrow criterion benchmark running (GKE) | trigger
Instance: c4a-highmem-16 (12 vCPU / 65 GiB) | Linux bench-c4169840798-646-56szd 6.12.55+ #1 SMP Sun Feb 1 08:59:41 UTC 2026 aarch64 GNU/Linux

CPU Details (lscpu)

Architecture:                            aarch64
CPU op-mode(s):                          64-bit
Byte Order:                              Little Endian
CPU(s):                                  16
On-line CPU(s) list:                     0-15
Vendor ID:                               ARM
Model name:                              Neoverse-V2
Model:                                   1
Thread(s) per core:                      1
Core(s) per cluster:                     16
Socket(s):                               -
Cluster(s):                              1
Stepping:                                r0p1
BogoMIPS:                                2000.00
Flags:                                   fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 sm3 sm4 asimddp sha512 sve asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp sve2 sveaes svepmull svebitperm svesha3 svesm4 flagm2 frint svei8mm svebf16 i8mm bf16 dgh rng bti
L1d cache:                               1 MiB (16 instances)
L1i cache:                               1 MiB (16 instances)
L2 cache:                                32 MiB (16 instances)
L3 cache:                                80 MiB (1 instance)
NUMA node(s):                            1
NUMA node0 CPU(s):                       0-15
Vulnerability Gather data sampling:      Not affected
Vulnerability Indirect target selection: Not affected
Vulnerability Itlb multihit:             Not affected
Vulnerability L1tf:                      Not affected
Vulnerability Mds:                       Not affected
Vulnerability Meltdown:                  Not affected
Vulnerability Mmio stale data:           Not affected
Vulnerability Reg file data sampling:    Not affected
Vulnerability Retbleed:                  Not affected
Vulnerability Spec rstack overflow:      Not affected
Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:                Mitigation; __user pointer sanitization
Vulnerability Spectre v2:                Mitigation; CSV2, BHB
Vulnerability Srbds:                     Not affected
Vulnerability Tsa:                       Not affected
Vulnerability Tsx async abort:           Not affected
Vulnerability Vmscape:                   Not affected

Comparing 9571_arrow-csv_custom_line_terminator (21f3146) to 61b5763 (merge-base) diff
BENCH_NAME=csv_writer
BENCH_COMMAND=cargo bench --features=arrow,async,test_common,experimental,object_store --bench csv_writer
BENCH_FILTER=
Results will be posted here when complete

File an issue against this benchmark runner

adriangbot · 2026-04-01T12:47:57Z

🤖 Arrow criterion benchmark completed (GKE) | trigger

Instance: c4a-highmem-16 (12 vCPU / 65 GiB)

CPU Details (lscpu)

Architecture:                            aarch64
CPU op-mode(s):                          64-bit
Byte Order:                              Little Endian
CPU(s):                                  16
On-line CPU(s) list:                     0-15
Vendor ID:                               ARM
Model name:                              Neoverse-V2
Model:                                   1
Thread(s) per core:                      1
Core(s) per cluster:                     16
Socket(s):                               -
Cluster(s):                              1
Stepping:                                r0p1
BogoMIPS:                                2000.00
Flags:                                   fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 sm3 sm4 asimddp sha512 sve asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp sve2 sveaes svepmull svebitperm svesha3 svesm4 flagm2 frint svei8mm svebf16 i8mm bf16 dgh rng bti
L1d cache:                               1 MiB (16 instances)
L1i cache:                               1 MiB (16 instances)
L2 cache:                                32 MiB (16 instances)
L3 cache:                                80 MiB (1 instance)
NUMA node(s):                            1
NUMA node0 CPU(s):                       0-15
Vulnerability Gather data sampling:      Not affected
Vulnerability Indirect target selection: Not affected
Vulnerability Itlb multihit:             Not affected
Vulnerability L1tf:                      Not affected
Vulnerability Mds:                       Not affected
Vulnerability Meltdown:                  Not affected
Vulnerability Mmio stale data:           Not affected
Vulnerability Reg file data sampling:    Not affected
Vulnerability Retbleed:                  Not affected
Vulnerability Spec rstack overflow:      Not affected
Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:                Mitigation; __user pointer sanitization
Vulnerability Spectre v2:                Mitigation; CSV2, BHB
Vulnerability Srbds:                     Not affected
Vulnerability Tsa:                       Not affected
Vulnerability Tsx async abort:           Not affected
Vulnerability Vmscape:                   Not affected

Details

group                    9571_arrow-csv_custom_line_terminator    main
-----                    -------------------------------------    ----
record_batches_to_csv    1.03     15.0±0.22µs        ? ?/sec      1.00     14.5±0.91µs        ? ?/sec

Resource Usage

base (merge-base)

Metric	Value
Wall time	10.7s
Peak memory	2.8 GiB
Avg memory	2.4 GiB
CPU user	5.8s
CPU sys	4.5s
Disk read	0 B
Disk write	581.9 MiB

branch

Metric	Value
Wall time	11.0s
Peak memory	2.8 GiB
Avg memory	2.5 GiB
CPU user	5.5s
CPU sys	4.2s
Disk read	0 B
Disk write	752.1 MiB

File an issue against this benchmark runner

alamb · 2026-04-01T21:08:09Z

run benchmarks csv_writer

adriangbot · 2026-04-01T21:11:09Z

🤖 Arrow criterion benchmark running (GKE) | trigger
Instance: c4a-highmem-16 (12 vCPU / 65 GiB) | Linux bench-c4172977264-651-pllmw 6.12.55+ #1 SMP Sun Feb 1 08:59:41 UTC 2026 aarch64 GNU/Linux

CPU Details (lscpu)

Architecture:                            aarch64
CPU op-mode(s):                          64-bit
Byte Order:                              Little Endian
CPU(s):                                  16
On-line CPU(s) list:                     0-15
Vendor ID:                               ARM
Model name:                              Neoverse-V2
Model:                                   1
Thread(s) per core:                      1
Core(s) per cluster:                     16
Socket(s):                               -
Cluster(s):                              1
Stepping:                                r0p1
BogoMIPS:                                2000.00
Flags:                                   fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 sm3 sm4 asimddp sha512 sve asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp sve2 sveaes svepmull svebitperm svesha3 svesm4 flagm2 frint svei8mm svebf16 i8mm bf16 dgh rng bti
L1d cache:                               1 MiB (16 instances)
L1i cache:                               1 MiB (16 instances)
L2 cache:                                32 MiB (16 instances)
L3 cache:                                80 MiB (1 instance)
NUMA node(s):                            1
NUMA node0 CPU(s):                       0-15
Vulnerability Gather data sampling:      Not affected
Vulnerability Indirect target selection: Not affected
Vulnerability Itlb multihit:             Not affected
Vulnerability L1tf:                      Not affected
Vulnerability Mds:                       Not affected
Vulnerability Meltdown:                  Not affected
Vulnerability Mmio stale data:           Not affected
Vulnerability Reg file data sampling:    Not affected
Vulnerability Retbleed:                  Not affected
Vulnerability Spec rstack overflow:      Not affected
Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:                Mitigation; __user pointer sanitization
Vulnerability Spectre v2:                Mitigation; CSV2, BHB
Vulnerability Srbds:                     Not affected
Vulnerability Tsa:                       Not affected
Vulnerability Tsx async abort:           Not affected
Vulnerability Vmscape:                   Not affected

Comparing 9571_arrow-csv_custom_line_terminator (21f3146) to 61b5763 (merge-base) diff
BENCH_NAME=csv_writer
BENCH_COMMAND=cargo bench --features=arrow,async,test_common,experimental,object_store --bench csv_writer
BENCH_FILTER=
Results will be posted here when complete

File an issue against this benchmark runner

adriangbot · 2026-04-01T21:11:42Z

🤖 Arrow criterion benchmark completed (GKE) | trigger

Instance: c4a-highmem-16 (12 vCPU / 65 GiB)

CPU Details (lscpu)

Architecture:                            aarch64
CPU op-mode(s):                          64-bit
Byte Order:                              Little Endian
CPU(s):                                  16
On-line CPU(s) list:                     0-15
Vendor ID:                               ARM
Model name:                              Neoverse-V2
Model:                                   1
Thread(s) per core:                      1
Core(s) per cluster:                     16
Socket(s):                               -
Cluster(s):                              1
Stepping:                                r0p1
BogoMIPS:                                2000.00
Flags:                                   fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 sm3 sm4 asimddp sha512 sve asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp sve2 sveaes svepmull svebitperm svesha3 svesm4 flagm2 frint svei8mm svebf16 i8mm bf16 dgh rng bti
L1d cache:                               1 MiB (16 instances)
L1i cache:                               1 MiB (16 instances)
L2 cache:                                32 MiB (16 instances)
L3 cache:                                80 MiB (1 instance)
NUMA node(s):                            1
NUMA node0 CPU(s):                       0-15
Vulnerability Gather data sampling:      Not affected
Vulnerability Indirect target selection: Not affected
Vulnerability Itlb multihit:             Not affected
Vulnerability L1tf:                      Not affected
Vulnerability Mds:                       Not affected
Vulnerability Meltdown:                  Not affected
Vulnerability Mmio stale data:           Not affected
Vulnerability Reg file data sampling:    Not affected
Vulnerability Retbleed:                  Not affected
Vulnerability Spec rstack overflow:      Not affected
Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:                Mitigation; __user pointer sanitization
Vulnerability Spectre v2:                Mitigation; CSV2, BHB
Vulnerability Srbds:                     Not affected
Vulnerability Tsa:                       Not affected
Vulnerability Tsx async abort:           Not affected
Vulnerability Vmscape:                   Not affected

Details

group                    9571_arrow-csv_custom_line_terminator    main
-----                    -------------------------------------    ----
record_batches_to_csv    1.01     14.7±0.38µs        ? ?/sec      1.00     14.5±0.12µs        ? ?/sec

Resource Usage

base (merge-base)

Metric	Value
Wall time	10.6s
Peak memory	2.8 GiB
Avg memory	2.3 GiB
CPU user	5.9s
CPU sys	4.5s
Disk read	0 B
Disk write	35.1 MiB

branch

Metric	Value
Wall time	11.5s
Peak memory	2.8 GiB
Avg memory	2.5 GiB
CPU user	5.6s
CPU sys	4.0s
Disk read	0 B
Disk write	1.5 GiB

File an issue against this benchmark runner

alamb · 2026-04-01T21:26:03Z

Performance results look good to me (no change)

# Which issue does this PR close?  - Closes apache#9571. # Rationale for this change  Enable configuring line terminator for CSV writer. # What changes are included in this PR?  See above. # Are these changes tested?  Yes, added tests. # Are there any user-facing changes?  Yes, expose option to set line terminator for CSV writer. --------- Co-authored-by: svranesevic <svranesevic@users.noreply.github.com> Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

* Working build * Bulk RLE encode (TODO: upstream) * Expose option to set line terminator (apache#9617 v58) * Fix `extend_nulls` panic for UnionArray (apache#9607 v58) (#82) --------- Co-authored-by: Thomas Peiselt <pi@kulturguerilla.org> Co-authored-by: Georgi Krastev <georgi.krastev@coralogix.com> Co-authored-by: Brent Gardner <bgardner@squarelabs.net>

Expose option to set line terminator for arrow-csv

093810e

github-actions Bot added the arrow Changes to the arrow crate label Mar 26, 2026

Revert accidental deletion

a16169f

alamb approved these changes Mar 27, 2026

View reviewed changes

alamb added 2 commits April 1, 2026 08:42

Reduce test replication

25a78cb

Merge remote-tracking branch 'apache/main' into 9571_arrow-csv_custom…

21f3146

…_line_terminator

alamb merged commit ec771cc into apache:main Apr 3, 2026
23 checks passed

avantgardnerio pushed a commit to coralogix/arrow-rs that referenced this pull request Apr 7, 2026

Expose option to set line terminator (apache#9617 v56+)

c18475f

avantgardnerio added a commit to coralogix/arrow-rs that referenced this pull request Apr 14, 2026

Expose option to set line terminator (apache#9617)

5a65fbd

Abhisheklearn12 mentioned this pull request Apr 19, 2026

Support record delimiter ("terminator" in Arrow terms) for CSV writing apache/datafusion#21027

Open

alamb mentioned this pull request Apr 23, 2026

Allow setting custom line terminator for CSV writer #9571

Closed

avantgardnerio mentioned this pull request Apr 28, 2026

CX-39170: Arrow-rs v57.0.0-cx.0 coralogix/arrow-rs#83

Closed

9 tasks

avantgardnerio added a commit to coralogix/arrow-rs that referenced this pull request Apr 29, 2026

Expose option to set line terminator (apache#9617)

f10dd19

avantgardnerio added a commit to coralogix/arrow-rs that referenced this pull request Jun 16, 2026

Expose option to set line terminator (apache#9617 v58)

4d7a3a4

avantgardnerio added a commit to coralogix/arrow-rs that referenced this pull request Jun 16, 2026

Expose option to set line terminator (apache#9617 v58)

6c4fbfa

Dandandan mentioned this pull request Jul 6, 2026

Rebase Coralogix patches onto upstream 57.3.1 coralogix/arrow-rs#88

Merged

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svranesevic commented Mar 26, 2026

Which issue does this PR close?

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

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