POC improve string view hash compute

[Rachelint]

Which issue does this PR close?

• Closes #.

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[Rachelint]

run benchmarks clickbench_partitioned

[adriangbot]

🤖 Benchmark running (GKE) | trigger
Instance: c4a-highmem-16 (12 vCPU / 65 GiB) | Linux bench-c4932027884-955-4f72q 6.12.85+ #1 SMP Mon May 11 08:17:35 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 improve-compare-in-view-map-v2 (7d5fa64) to f34a676 (merge-base) diff using: clickbench_partitioned
Results will be posted here when complete

---

File an issue against this benchmark runner

[adriangbot]

🤖 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

Comparing HEAD and improve-compare-in-view-map-v2
--------------------
Benchmark clickbench_partitioned.json
--------------------
┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┓
┃ Query     ┃                                  HEAD ┃         improve-compare-in-view-map-v2 ┃        Change ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━┩
│ QQuery 0  │          1.22 / 3.89 ±5.28 / 14.45 ms │           1.21 / 4.07 ±5.63 / 15.33 ms │     no change │
│ QQuery 1  │        12.64 / 12.89 ±0.20 / 13.26 ms │         12.84 / 12.92 ±0.11 / 13.15 ms │     no change │
│ QQuery 2  │        35.99 / 36.35 ±0.23 / 36.69 ms │         36.48 / 36.85 ±0.35 / 37.42 ms │     no change │
│ QQuery 3  │        30.37 / 31.79 ±0.77 / 32.64 ms │         30.82 / 31.15 ±0.30 / 31.64 ms │     no change │
│ QQuery 4  │     222.40 / 224.70 ±1.92 / 227.21 ms │      221.66 / 224.46 ±3.42 / 231.03 ms │     no change │
│ QQuery 5  │     268.60 / 271.89 ±1.73 / 273.68 ms │                                   FAIL │  incomparable │
│ QQuery 6  │           1.25 / 1.41 ±0.22 / 1.85 ms │            1.27 / 1.41 ±0.21 / 1.81 ms │     no change │
│ QQuery 7  │        13.83 / 13.98 ±0.11 / 14.17 ms │         16.11 / 21.52 ±5.56 / 31.46 ms │  1.54x slower │
│ QQuery 8  │     317.32 / 323.39 ±4.10 / 327.92 ms │      321.27 / 323.58 ±2.65 / 327.72 ms │     no change │
│ QQuery 9  │     443.95 / 457.34 ±8.02 / 467.38 ms │      449.63 / 455.91 ±5.81 / 463.39 ms │     no change │
│ QQuery 10 │        71.43 / 72.56 ±0.92 / 73.80 ms │         71.50 / 72.47 ±0.80 / 73.76 ms │     no change │
│ QQuery 11 │        83.43 / 84.71 ±1.07 / 86.12 ms │         83.51 / 84.76 ±1.00 / 86.32 ms │     no change │
│ QQuery 12 │     266.41 / 273.88 ±6.57 / 285.30 ms │                                   FAIL │  incomparable │
│ QQuery 13 │     372.77 / 381.38 ±8.04 / 391.55 ms │     897.86 / 932.49 ±30.05 / 985.57 ms │  2.45x slower │
│ QQuery 14 │     285.30 / 293.97 ±5.66 / 300.98 ms │      288.12 / 298.55 ±8.11 / 307.68 ms │     no change │
│ QQuery 15 │     275.14 / 283.20 ±5.27 / 291.71 ms │      272.37 / 280.18 ±7.11 / 288.82 ms │     no change │
│ QQuery 16 │     615.09 / 620.47 ±4.69 / 626.22 ms │      610.81 / 622.12 ±9.45 / 638.11 ms │     no change │
│ QQuery 17 │     621.30 / 629.19 ±4.89 / 635.31 ms │      622.56 / 629.09 ±6.66 / 641.87 ms │     no change │
│ QQuery 18 │ 1243.12 / 1271.68 ±17.57 / 1291.18 ms │  1256.14 / 1275.18 ±17.96 / 1305.48 ms │     no change │
│ QQuery 19 │       27.92 / 38.55 ±15.07 / 66.91 ms │        27.98 / 34.88 ±12.27 / 59.37 ms │ +1.11x faster │
│ QQuery 20 │     515.79 / 526.99 ±7.93 / 536.32 ms │      512.02 / 521.05 ±8.11 / 533.31 ms │     no change │
│ QQuery 21 │     514.09 / 521.41 ±3.91 / 525.11 ms │      517.54 / 528.45 ±9.04 / 539.19 ms │     no change │
│ QQuery 22 │    990.60 / 999.04 ±5.89 / 1008.24 ms │   995.84 / 1013.81 ±14.87 / 1034.40 ms │     no change │
│ QQuery 23 │ 3120.16 / 3134.80 ±13.60 / 3154.70 ms │  3083.03 / 3128.62 ±27.10 / 3151.66 ms │     no change │
│ QQuery 24 │        41.32 / 42.77 ±2.14 / 46.97 ms │         41.12 / 44.27 ±5.85 / 55.97 ms │     no change │
│ QQuery 25 │     111.11 / 112.44 ±1.05 / 113.89 ms │      112.29 / 116.35 ±6.90 / 130.07 ms │     no change │
│ QQuery 26 │        42.04 / 43.76 ±2.27 / 48.17 ms │         41.39 / 42.13 ±0.60 / 43.09 ms │     no change │
│ QQuery 27 │    671.20 / 685.71 ±11.95 / 703.91 ms │      670.17 / 672.96 ±3.25 / 679.13 ms │     no change │
│ QQuery 28 │  3021.48 / 3033.04 ±8.61 / 3042.55 ms │                                   FAIL │  incomparable │
│ QQuery 29 │        40.70 / 43.18 ±4.37 / 51.92 ms │        41.09 / 51.78 ±14.33 / 79.59 ms │  1.20x slower │
│ QQuery 30 │    298.42 / 314.41 ±16.86 / 345.31 ms │      297.43 / 304.82 ±6.00 / 315.55 ms │     no change │
│ QQuery 31 │     278.08 / 291.36 ±8.49 / 303.14 ms │     284.41 / 301.16 ±13.20 / 319.51 ms │     no change │
│ QQuery 32 │     931.51 / 941.62 ±8.17 / 951.21 ms │    937.35 / 982.78 ±41.74 / 1037.41 ms │     no change │
│ QQuery 33 │ 1454.01 / 1478.26 ±23.36 / 1513.01 ms │ 9163.91 / 9306.94 ±116.50 / 9468.45 ms │  6.30x slower │
│ QQuery 34 │ 1465.69 / 1489.18 ±17.97 / 1516.16 ms │ 9327.88 / 9411.08 ±103.73 / 9603.45 ms │  6.32x slower │
│ QQuery 35 │    278.64 / 289.32 ±14.51 / 317.80 ms │     277.74 / 314.26 ±55.91 / 423.25 ms │  1.09x slower │
│ QQuery 36 │        64.02 / 67.58 ±4.47 / 76.19 ms │     189.63 / 206.39 ±15.38 / 225.72 ms │  3.05x slower │
│ QQuery 37 │        35.51 / 41.18 ±5.00 / 49.37 ms │         48.85 / 51.48 ±2.70 / 54.94 ms │  1.25x slower │
│ QQuery 38 │        41.00 / 44.30 ±4.01 / 52.16 ms │         43.56 / 44.99 ±1.46 / 47.57 ms │     no change │
│ QQuery 39 │     137.37 / 149.73 ±7.35 / 158.49 ms │      149.57 / 157.55 ±8.64 / 173.12 ms │  1.05x slower │
│ QQuery 40 │        13.97 / 14.15 ±0.14 / 14.29 ms │         14.39 / 15.89 ±2.07 / 19.94 ms │  1.12x slower │
│ QQuery 41 │        13.73 / 15.29 ±2.94 / 21.17 ms │         13.73 / 14.05 ±0.27 / 14.45 ms │ +1.09x faster │
│ QQuery 42 │        12.90 / 14.65 ±2.90 / 20.44 ms │         13.00 / 15.42 ±4.08 / 23.57 ms │  1.05x slower │
└───────────┴───────────────────────────────────────┴────────────────────────────────────────┴───────────────┘
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━┓
┃ Benchmark Summary                             ┃            ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━┩
│ Total Time (HEAD)                             │ 16042.59ms │
│ Total Time (improve-compare-in-view-map-v2)   │ 32587.81ms │
│ Average Time (HEAD)                           │   401.06ms │
│ Average Time (improve-compare-in-view-map-v2) │   814.70ms │
│ Queries Faster                                │          2 │
│ Queries Slower                                │         11 │
│ Queries with No Change                        │         27 │
│ Queries with Failure                          │          3 │
└───────────────────────────────────────────────┴────────────┘

Resource Usage

clickbench_partitioned — base (merge-base)

Metric	Value
Wall time	100.0s
Peak memory	11.0 GiB
Avg memory	4.6 GiB
CPU user	1011.1s
CPU sys	67.8s
Peak spill	0 B

clickbench_partitioned — branch

Metric	Value
Wall time	170.0s
Peak memory	11.7 GiB
Avg memory	4.9 GiB
CPU user	1799.8s
CPU sys	78.7s
Peak spill	0 B

---

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