More quantile refactoring

[RAMitchell]

No description provided.

[Copilot]

Pull request overview

This pull request removes the sorted sketching functionality from XGBoost, simplifying the quantile sketching implementation by standardizing on the row-wise host sketching approach.

Changes:

• Removes SortedQuantile and SortedSketchContainer classes from the quantile sketching implementation
• Simplifies function signatures by removing the sorted_sketch parameter from SketchOnDMatrix and GHistIndexMatrix constructors
• Removes tests for sorted sketching variants and cleans up code formatting

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/common/quantile.h	Removes SortedQuantile and SortedSketchContainer classes; refactors Queue struct to use std::pair and std::vector directly; adds helper methods Size(), SetSize(), Clear(), and SetFromSorted() to WQSummary
src/common/quantile.cc	Removes SortedSketchContainer::PushColPage implementation; updates references to use new Size() method instead of current_elements
src/common/hist_util.h	Removes use_sorted parameter from SketchOnDMatrix function signature
src/common/hist_util.cc	Simplifies SketchOnDMatrix implementation to only use HostSketchContainer; removes conditional logic for sorted vs unsorted sketching
src/data/gradient_index.h	Removes sorted_sketch parameter from GHistIndexMatrix constructor
src/data/gradient_index.cc	Removes sorted_sketch parameter and related comments; updates constructor implementation
src/data/simple_dmatrix.cc	Removes sorted_sketch variable and parameter from GHistIndexMatrix construction
src/data/sparse_page_dmatrix.cc	Removes sorted_sketch variable and parameter from SketchOnDMatrix call
tests/cpp/common/test_quantile.cc	Removes sorted sketching test cases and template parameters; simplifies test functions
tests/cpp/common/test_hist_util.cc	Removes sorted sketching test variants; updates function calls to remove parameters
tests/cpp/data/test_gradient_index.cc	Updates function calls to remove sorted_sketch parameter; reformats include statements
tests/cpp/data/test_sparse_page_dmatrix.cc	Updates SketchOnDMatrix call to remove parameter
tests/cpp/common/test_column_matrix.cc	Updates GHistIndexMatrix constructor calls to remove parameter
tests/cpp/tree/hist/test_histogram.cc	Updates SketchOnDMatrix call to remove parameter
tests/cpp/tree/hist/test_evaluate_splits.cc	Updates GHistIndexMatrix constructor calls and reformats code for consistency

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[RAMitchell]

After benchmarking, I think the performance reduction of around 50% is too high, so I will just refactor instead and we can remove if/when approx gets removed.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

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