Converting container builder #31977
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Converting container builder #31977
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At the moment, we have many places where we consolidate opportunistically to reduce the amount of data as early as possible. This works fine for vectors because we have dedicated functions, and vectors offer mutable access to their contents. It's much harder to implement for containers that do not offer mutable access, such as columns. To avoid losing the benefit of eager consolidation, we introduce a converting container builder that wraps two container builders: The first absorbs inputs, the second absorbs the outputs of the first. This way, we can consolidate the inputs and then stage them in a column, combining the benefits of consolidation and columnar data layout. This has the beneficial effect that allocations contained in the consolidated output do not last beyond the second container builder, i.e., they are short-lived and can be easily recycled through the allocator on the same thread. Signed-off-by: Moritz Hoffmann <[email protected]>
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At the moment, we have many places where we consolidate opportunistically to reduce the amount of data as early as possible. This works fine for vectors because we have dedicated functions, and vectors offer mutable access to their contents. It's much harder to implement for containers that do not offer mutable access, such as columns. To avoid losing the benefit of eager consolidation, we introduce a converting container builder that wraps two container builders: The first absorbs inputs, the second absorbs the outputs of the first. This way, we can consolidate the inputs and then stage them in a column, combining the benefits of consolidation and columnar data layout.
This has the beneficial effect that allocations contained in the consolidated output do not last beyond the second container builder, i.e., they are short-lived and can be easily recycled through the allocator on the same thread.
Checklist
$T ⇔ Proto$Tmapping (possibly in a backwards-incompatible way), then it is tagged with aT-protolabel.