[minmax] 8-bit benchmark

[arkrishn94]

Add support for 8-bit queries in the exhaustive benchmark for minmax in diskann-benchmark. Here is a sample result -

Dataset:  958,152 vectors, dim=896, float16
Distance: cosine    Transform: double_hadamard(same)    Threads: 12

+----------+----------------+--------------------+-------------+
| num_bits | query_layout   | mean search (us)   | R@10/10 (%) |
+----------+----------------+--------------------+-------------+
|    2     | full_precision |       233,416      |    56.58    |
|    2     | eight_bit      |       222,594      |    56.60    |
|    4     | full_precision |       337,161      |    88.84    |
|    4     | eight_bit      |       195,933      |    88.87    |
+----------+----------------+--------------------+-------------+

[Copilot]

Pull request overview

Adds an eight_bit query layout option for the MinMax exhaustive benchmark in diskann-benchmark, enabling benchmarking where queries are compressed to 8-bit even when the indexed data uses a different MinMax bit-rate.

Changes:

• Extend MinMaxQuery with a new EightBit variant and include it in the MinMax exhaustive example input defaults.
• Update the MinMax exhaustive backend to build distance computers for 8-bit-compressed queries (Data<8>).
• Update the minmax-exhaustive.json example to include "eight_bit" in some jobs and adjust several job parameters.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
diskann-benchmark/src/inputs/exhaustive.rs	Adds MinMaxQuery::EightBit and includes it in the MinMax example query_layouts.
diskann-benchmark/src/backend/exhaustive/minmax.rs	Adds support for 8-bit query compression in the exhaustive MinMax distance computer creation path.
diskann-benchmark/example/minmax-exhaustive.json	Updates example jobs to include eight_bit in some cases and changes several job distances/query_layout sets.

Comments suppressed due to low confidence (1)

diskann-benchmark/src/backend/exhaustive/minmax.rs:624

• The new MinMaxQuery::EightBit path supports multiple distance measures at runtime, but the updated example/minmax-exhaustive.json only exercises eight_bit for squared_l2. To avoid regressions in the inner_product/cosine branches (which are easy to break with trait-bound changes), add at least one integration example job that uses query_layouts: ["eight_bit", ...] with inner_product and/or cosine, or add a focused test that runs those combinations.

                MinMaxQuery::EightBit => {
                    let mut compressed = Data::<8>::new_boxed(output_dim);
                    quantizer.compress_into(query, compressed.reborrow_mut())?;

                    match self.measure {
                        SimilarityMeasure::SquaredL2 => {
                            let inner: MinMaxL2Squared = quantizer.as_functor();
                            Ok(Boxed::new(Curried::new(inner, compressed)))

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.32%. Comparing base (20295a4) to head (37874d2).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
diskann-benchmark/src/inputs/exhaustive.rs	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #959      +/-   ##
==========================================
- Coverage   89.32%   89.32%   -0.01%     
==========================================
  Files         448      447       -1     
  Lines       83563    83260     -303     
==========================================
- Hits        74645    74369     -276     
+ Misses       8918     8891      -27     

Flag	Coverage Δ
miri	89.32% <0.00%> (-0.01%)	⬇️
unittests	89.16% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
diskann-benchmark/src/backend/exhaustive/minmax.rs	100.00% <ø> (ø)
diskann-benchmark/src/inputs/exhaustive.rs	28.92% <0.00%> (-0.53%)	⬇️

... and 11 files with indirect coverage changes

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