Optimize cast(uuid as varchar) #10361
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Summary:
boost::lexical_cast used to implement cast(uuid as varchar) is very slow.
Replace with custom optimization.
Microbenchmark shows 20x improvement.
The benchmark compares uuid() with cast(uuid() as varchar). The latter includes the code of the former plus the cost of the cast. Before the change, uuid() + cast was 16s, 10s more than uuid() alone. After the change, uuid() + cast() is just 0.5s more.
Before:
```
============================================================================
[...]hmarks/ExpressionBenchmarkBuilder.cpp relative time/iter iters/s
============================================================================
cast##no_cast 6.33s 157.86m
cast##as_varchar 16.54s 60.45m
```
After:
```
============================================================================
cast##no_cast 6.29s 159.10m
cast##as_varchar 6.81s 146.74m
----------------------------------------------------------------------------
```
Profile before the optimization: {F1735048022}
Differential Revision: D59229653
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This pull request was exported from Phabricator. Differential Revision: D59229653 |
xiaoxmeng
approved these changes
Jul 1, 2024
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Summary:
boost::lexical_cast used to implement cast(uuid as varchar) is very slow.
Replace with custom optimization.
Microbenchmark shows 20x improvement.
The benchmark compares uuid() with cast(uuid() as varchar). The latter includes the code of the former plus the cost of the cast. Before the change, uuid() + cast was 16s, 10s more than uuid() alone. After the change, uuid() + cast() is just 0.5s more.
Before:
After:
Profile before the optimization: {F1735048022}
Differential Revision: D59229653