perf: Additional optimizations for cast from string to int #3048

andygrove · 2026-01-06T20:12:07Z

Which issue does this PR close?

N/A

Rationale for this change

This follows on from #3017 and makes some additional optimizations.

See comment #3048 (comment) for criterion benchmark results.

What changes are included in this PR?

use trim_ascii instead of custom trim logic
use two loops in do_parse_string_to_int_legacy and remove mutable parse_sign_and_digits
stop matching on eval mode for every row (do it once per batch instead)

How are these changes tested?

Existing tests.

andygrove · 2026-01-06T20:26:10Z

native/spark-expr/src/conversion_funcs/cast.rs


 macro_rules! cast_utf8_to_int {
-    ($array:expr, $eval_mode:expr, $array_type:ty, $cast_method:ident) => {{
+    ($array:expr, $array_type:ty, $parse_fn:expr) => {{


Pass in the parsing function as a closure rather than passing in the eval mode and then matching on that for each row.

Thats super nice

andygrove · 2026-01-06T20:27:15Z

native/spark-expr/src/conversion_funcs/cast.rs

-    match eval_mode {
-        EvalMode::Legacy => do_parse_string_to_int_legacy(str, min_value),
-        EvalMode::Ansi => do_parse_string_to_int_ansi(str, type_name, min_value),
-        EvalMode::Try => do_parse_string_to_int_try(str, min_value),
-    }


This was happening once per row

andygrove · 2026-01-06T20:53:18Z

Current performance compared to main branch:

cast_string_to_int/legacy/i8
                        time:   [5.9209 µs 5.9392 µs 5.9592 µs]
                        change: [−11.695% −11.370% −11.025%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 4 outliers among 100 measurements (4.00%)
  4 (4.00%) high mild
cast_string_to_int/legacy/i16
                        time:   [6.0520 µs 6.0623 µs 6.0752 µs]
                        change: [−19.180% −16.832% −14.698%] (p = 0.00 < 0.05)
                        Performance has improved.
cast_string_to_int/legacy/i32
                        time:   [10.351 µs 10.465 µs 10.588 µs]
                        change: [−8.5234% −7.6387% −6.8160%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 11 outliers among 100 measurements (11.00%)
  11 (11.00%) low mild
cast_string_to_int/legacy/i64
                        time:   [9.8147 µs 9.8431 µs 9.8750 µs]
                        change: [−20.510% −20.227% −19.963%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 2 outliers among 100 measurements (2.00%)
  2 (2.00%) high mild

cast_string_to_int/ansi/i8
                        time:   [5.9662 µs 5.9738 µs 5.9833 µs]
                        change: [+3.5123% +3.8189% +4.1332%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  5 (5.00%) high mild
  11 (11.00%) high severe
cast_string_to_int/ansi/i16
                        time:   [6.0278 µs 6.0633 µs 6.0965 µs]
                        change: [+4.7100% +5.2768% +5.8408%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 18 outliers among 100 measurements (18.00%)
  17 (17.00%) high mild
  1 (1.00%) high severe
cast_string_to_int/ansi/i32
                        time:   [11.561 µs 12.055 µs 12.488 µs]
                        change: [−4.3485% +0.7326% +5.7014%] (p = 0.77 > 0.05)
                        No change in performance detected.
cast_string_to_int/ansi/i64
                        time:   [8.9904 µs 9.0207 µs 9.0561 µs]
                        change: [−12.821% −12.447% −12.056%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 21 outliers among 100 measurements (21.00%)
  6 (6.00%) high mild
  15 (15.00%) high severe

cast_string_to_int/try/i8
                        time:   [5.3065 µs 5.3077 µs 5.3088 µs]
                        change: [−12.228% −11.963% −11.694%] (p = 0.00 < 0.05)
                        Performance has improved.
cast_string_to_int/try/i16
                        time:   [5.3181 µs 5.3339 µs 5.3510 µs]
                        change: [−14.996% −12.856% −11.115%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  9 (9.00%) high mild
  5 (5.00%) high severe
cast_string_to_int/try/i32
                        time:   [8.9089 µs 8.9433 µs 8.9790 µs]
                        change: [−23.521% −21.359% −19.212%] (p = 0.00 < 0.05)
                        Performance has improved.
cast_string_to_int/try/i64
                        time:   [8.9110 µs 8.9753 µs 9.0582 µs]
                        change: [−33.677% −30.213% −26.785%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  2 (2.00%) high mild
  6 (6.00%) high severe

cast_string_to_int/legacy_decimals/i32
                        time:   [10.346 µs 10.361 µs 10.383 µs]
                        change: [−16.404% −15.946% −15.512%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 16 outliers among 100 measurements (16.00%)
  6 (6.00%) high mild
  10 (10.00%) high severe
cast_string_to_int/legacy_decimals/i64
                        time:   [10.409 µs 10.434 µs 10.467 µs]
                        change: [−18.687% −17.862% −17.208%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 18 outliers among 100 measurements (18.00%)
  7 (7.00%) high mild
  11 (11.00%) high severe

codecov-commenter · 2026-01-06T20:55:13Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.50%. Comparing base (f09f8af) to head (1eb4b39).
⚠️ Report is 832 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3048      +/-   ##
============================================
+ Coverage     56.12%   59.50%   +3.37%     
- Complexity      976     1381     +405     
============================================
  Files           119      167      +48     
  Lines         11743    15522    +3779     
  Branches       2251     2575     +324     
============================================
+ Hits           6591     9236    +2645     
- Misses         4012     4989     +977     
- Partials       1140     1297     +157

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comphead · 2026-01-08T16:35:36Z

native/spark-expr/src/conversion_funcs/cast.rs

-    .map(|v| v as i16))
+fn parse_string_to_i8_legacy(str: &str) -> SparkResult<Option<i8>> {
+    match do_parse_string_to_int_legacy::<i32>(str, i32::MIN)? {
+        None => Ok(None),


Suggested change

None => Ok(None),

?

comphead

Thanks @andygrove it is similar to #2600 (comment) suggestion and thanks for addressing those issues

andygrove · 2026-01-08T17:02:43Z

Thanks @andygrove it is similar to #2600 (comment) suggestion and thanks for addressing those issues

I'll take a look next.

coderfender · 2026-01-09T05:39:29Z

thank you @andygrove

andygrove added 4 commits January 6, 2026 12:43

use trim_ascii

8ccd4aa

minor

06ae139

use two loops and remove mutable parse_sign_and_digits variable

cbf68bb

remove per-row eval mode check and expand benchmarks

e28d52a

andygrove commented Jan 6, 2026

View reviewed changes

more cleanup

37b90fb

andygrove changed the title ~~minor: small improvements in cast from string to int [WIP]~~ perf: Additional optimizations for cast from string to int [WIP] Jan 6, 2026

fix regression and update benchmark

b56aa04

andygrove changed the title ~~perf: Additional optimizations for cast from string to int [WIP]~~ perf: Additional optimizations for cast from string to int Jan 6, 2026

andygrove mentioned this pull request Jan 7, 2026

perf: Improve criterion benchmarks for cast string to int #3049

Merged

andygrove added 2 commits January 7, 2026 09:11

Merge remote-tracking branch 'apache/main' into cast-to-int-perf

b0548a0

upmerge and improve benchmark

1510f62

andygrove marked this pull request as ready for review January 7, 2026 16:19

comphead reviewed Jan 8, 2026

View reviewed changes

comphead approved these changes Jan 8, 2026

View reviewed changes

address feedback

1eb4b39

andygrove merged commit c7aad67 into apache:main Jan 8, 2026
119 checks passed

andygrove deleted the cast-to-int-perf branch January 8, 2026 18:34

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perf: Additional optimizations for cast from string to int #3048

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