apache
GH-39565: [C++] Do not concatenate ChunkedArray when running take function
Rationale for this change
We can avoid extra unecessary work and memory consumption of concatenating chunks when running take, we can directly run the take on the chunks at the only cost of remapping the indices which are usually much fewer than the size of the array we are applying take on.
Are these changes tested?
Two tests already existed that verify take on ChunkedArray and they covered the corner cases well, the only tweak necessary to those tests was that now take returns a chunkedarray made of multiple chunks instead of a single one.
- Closes: #39565
:warning: GitHub issue #39565 has been automatically assigned in GitHub to PR creator.
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@felipecrv @amol- Should this PR be kept open now that #40206 was merged?
I think so, this PR is focused on optimizing TakeCA, while the one that was merged was focused on TakeCC
Before my PR: TakeCC made num_chunks Concatenate(chunks) calls.
After my PR: TakeCC makes 1 Concatenate(chunks) call.
Next step (and goal of amol's PR/issue pair): 0 concatenations.
I opened #41700 which can handle all the fixed-width types without concatenation.