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e57252092c
CQL evolved several expression evaluation mechanisms: WHERE clause, selectors (the SELECT clause), and the LWT IF clause are just some examples. Most now use expressions, which use managed_bytes_opt as the underlying value representation, but selectors still use bytes_opt. This poses two problems: 1. bytes_opt generates large contiguous allocations when used with large blobs, impacting latency 2. trying to use expressions with bytes_opt will incur a copy, reducing performance To solve the problem, we harmonize the data types to managed_bytes_opt (#13216 notwithstanding). This is somewhat difficult since the source of the values are views into a bytes_ostream. However, luckily bytes_ostream and managed_bytes_view are mostly compatible so with a little effort this can be done. The series is neutral wrt performance: before: ``` 222118.61 tps ( 61.1 allocs/op, 12.1 tasks/op, 43092 insns/op, 0 errors) 224250.14 tps ( 61.1 allocs/op, 12.1 tasks/op, 43094 insns/op, 0 errors) 224115.66 tps ( 61.1 allocs/op, 12.1 tasks/op, 43092 insns/op, 0 errors) 223508.70 tps ( 61.1 allocs/op, 12.1 tasks/op, 43107 insns/op, 0 errors) 223498.04 tps ( 61.1 allocs/op, 12.1 tasks/op, 43087 insns/op, 0 errors) ``` after: ``` 220708.37 tps ( 61.1 allocs/op, 12.1 tasks/op, 43118 insns/op, 0 errors) 225168.99 tps ( 61.1 allocs/op, 12.1 tasks/op, 43081 insns/op, 0 errors) 222406.00 tps ( 61.1 allocs/op, 12.1 tasks/op, 43088 insns/op, 0 errors) 224608.27 tps ( 61.1 allocs/op, 12.1 tasks/op, 43102 insns/op, 0 errors) 225458.32 tps ( 61.1 allocs/op, 12.1 tasks/op, 43098 insns/op, 0 errors) ``` Though I expect with some more effort we can eliminate some copies. Closes #13637 * github.com:scylladb/scylladb: cql3: untyped_result_set: switch to managed_bytes_view as the cell type cql3: result_set: switch cell data type from bytes_opt to managed_bytes_opt cql3: untyped_result_set: always own data types: abstract_type: add mixed-type versions of compare() and equal() utils/managed_bytes, serializer: add conversion between buffer_view<bytes_ostream> and managed_bytes_view utils: managed_bytes: add bidirectional conversion between bytes_opt and managed_bytes_opt utils: managed_bytes: add managed_bytes_view::with_linearized() utils: managed_bytes: mark managed_bytes_view::is_linearized() const