Improve visitor performance by reducing Vec and String allocations #6337
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Improve visitor performance by reducing Vec and String allocations #6337
Vec and String allocations #6337Conversation
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Benchmarks: Random AccessSummary
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Benchmarks: TPC-H SF=1 on NVMESummary
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Benchmarks: FineWeb NVMeSummary
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Benchmarks: TPC-DS SF=1 on NVMESummary
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Benchmarks: TPC-H SF=1 on S3Summary
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Benchmarks: TPC-H SF=10 on NVMESummary
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Benchmarks: FineWeb S3Summary
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Benchmarks: Statistical and Population GeneticsSummary
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🚨🚨🚨❌❌❌ SQL BENCHMARK FAILED ❌❌❌🚨🚨🚨Benchmark |
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Benchmarks: Clickbench on NVMESummary
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Benchmarks: CompressionSummary
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Merging this PR will degrade performance by 13.38%
Performance Changes
Comparing 
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robert3005
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Feb 6, 2026
robert3005
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Feb 6, 2026
AdamGS
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Benchmarks: PolarSignals ProfilingSummary
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Signed-off-by: Adam Gutglick <adam@spiraldb.com>
Signed-off-by: Adam Gutglick <adam@spiraldb.com>
Signed-off-by: Adam Gutglick <adam@spiraldb.com>
Signed-off-by: Adam Gutglick <adam@spiraldb.com>
Signed-off-by: Adam Gutglick <adam@spiraldb.com>
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moving the filter piece into a different PR so I can try and measure a bigger thing |
Signed-off-by: Adam Gutglick <adam@spiraldb.com>
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The codspeed improvement here is real 🥳, like 20% of those benchmarks was just formatting the names of the chunks. |
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@gatesn following our conversation on Friday, are you going to break these APIs and I should just close this PR? |
Signed-off-by: Adam Gutglick <adam@spiraldb.com>
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Vec and String allocations
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I will take a look. Very keen to take these performance wins, just want to make sure it moves in the direction we were going to avoid extra work. |
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Using
dhat, identified these two code paths as heavy allocators, running the full tpch benchmark.This PR fills out many default implementations in
VisitorVTable, making them much more efficient for many cases, both by reducing recursive function calls and by not formatting names. As far as I can tell - many of the improvements shown by codspeed are completely real here.Using the existing iterator when filtering instead of allocating a Vec saves about 2GB of memory allocation (around 1.6% of all memory allocated), which happens in a tiny amount of allocations (0.02%).Moving to a separate PR, I want to try and make a bigger change and be able to measure it.nth_child(should just bechild?) was just another offender that was easy to experiment with, it doesn't allocate a lot of data but it does save ~0.6% of all allocations.