(RFC) Refactor search interface with unified SearchDispatch trait by narendatha · Pull Request #773 · microsoft/DiskANN

narendatha · 2026-02-12T16:55:30Z

Refactor search interface with unified SearchDispatch trait

Summary

This PR refactors the search interface in diskann to provide a unified entry point via the SearchDispatch trait, improving code organization and API clarity. This also removes (un)popular SearchParams and search specific structs. This PR also removes (un)popular SearchParamsand replaces with search specific structs, so it is clear what params are used and which ones are ignored.

Changes

New Architecture

SearchDispatch trait - A unified dispatch interface that all search types implement, enabling a single index.search() entry point
Separate search type files:
- dispatch.rs - Core trait definition
- graph_search.rs - Standard k-NN graph search (GraphSearch, RecordedGraphSearch)
- range_search.rs - Range-based search (RangeSearch, RangeSearchOutput)
- multihop_search.rs - Label-filtered search (MultihopSearch)
- diverse_search.rs - Diversity-aware search (DiverseSearch, feature-gated)

API Changes

Before	After
`index.execute_search(..., parameters, ...)`	`index.search(..., search_params, ...)`
`index.search_recorded(...)`	`index.debug_search(...)`
Multiple search methods	Single `search()` with dispatch

Code Organization

Moved internal implementations (range_search_internal, multihop_search_internal) to their respective search type files
Moved NotInMutWithLabelCheck helper to multihop_search.rs
Added From impls for SearchParams -> GraphSearch and RangeSearchParams -> RangeSearch
Removed convenience methods (graph_search, multihop_search, range_search) from DiskANNIndex to avoid encouraging direct use
Added local test helper functions where needed for backwards compatibility

Other

Renamed search_recorded -> debug_search to clearly signal debug-only intent
Bumped version to 0.46.0

Usage Example

use diskann::graph::{GraphSearch, RangeSearch, MultihopSearch};

// Standard k-NN search
let params = GraphSearch::new(10, 100, None)?;
let stats = index.search(&strategy, &context, &query, &params, &mut output).await?;

// Range search
let params = RangeSearch::new(100, 0.5)?;
let result = index.search(&strategy, &context, &query, &params, &mut ()).await?;

// Filtered search
let params = MultihopSearch::new(GraphSearch::new(10, 100, None)?, &filter);
let stats = index.search(&strategy, &context, &query, &params, &mut output).await?;

Why flat_search is not included

flat_search remains a separate method because it has unique constraints incompatible with SearchDispatch: (1) it requires an additional generic bound SearchAccessor<'a>: IdIterator<I> that forces the strategy's accessor to support iteration over all IDs - a capability not all strategies provide, and (2) it takes an extra vector_filter closure parameter that other search types don't need. Since flat_search is fundamentally a linear scan with filtering rather than a graph traversal, keeping it as a distinct method with its own signature is cleaner than complicating the trait to accommodate it.

Testing

All existing tests pass
cargo build --workspace
cargo test -p diskann -p diskann-providers -p diskann-disk

- Add SearchDispatch trait for unified search entry point - Split search types into separate files (graph_search, range_search, multihop_search, diverse_search) - Rename execute_search to search, parameters to search_params - Rename search_recorded to debug_search to signal debug-only intent - Move internal implementations to respective search type files - Add From impls for SearchParams/RangeSearchParams to new types - Add test helper functions in test modules for backwards compat - Bump version to 0.46.0

Copilot

Pull request overview

This PR refactors the search interface in the diskann crate to provide a unified entry point via the SearchDispatch trait. The refactoring improves code organization by moving search implementations to dedicated files and consolidates the API around a single index.search() method that dispatches to type-specific implementations.

Changes:

Introduces SearchDispatch trait as the unified search interface, with separate implementations for standard graph search, range search, multihop (label-filtered) search, and diversity-aware search
Replaces multiple search methods (execute_search, multihop_search, range_search) with a single search() method that delegates to SearchDispatch::dispatch()
Renames search_recorded to debug_search to clearly signal debug-only intent
Maintains backward compatibility by implementing SearchDispatch for the legacy SearchParams type

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
`diskann/src/graph/search/dispatch.rs`	Core `SearchDispatch` trait definition
`diskann/src/graph/search/graph_search.rs`	Standard k-NN graph search implementation (`GraphSearch`, `RecordedGraphSearch`)
`diskann/src/graph/search/range_search.rs`	Range-based search implementation and `range_search_internal` helper
`diskann/src/graph/search/multihop_search.rs`	Label-filtered search and `multihop_search_internal` helper, includes `NotInMutWithLabelCheck` predicate
`diskann/src/graph/search/diverse_search.rs`	Feature-gated diversity-aware search implementation
`diskann/src/graph/search/mod.rs`	Module organization with public re-exports
`diskann/src/graph/mod.rs`	Top-level re-exports of search types
`diskann/src/graph/index.rs`	New unified `search()` method, renamed `debug_search()`, removed old search methods, made internal helpers `pub(crate)`
`diskann/src/graph/test/cases/grid.rs`	Updated to use `GraphSearch::new()` and `params.k`
`diskann-providers/src/index/diskann_async.rs`	Test helper functions for backward-compatible multihop and range search calls
`diskann-providers/src/index/wrapped_async.rs`	Converts `SearchParams` to `GraphSearch` for unified API
`diskann-disk/src/search/provider/disk_provider.rs`	Updated to use `GraphSearch` and renamed `debug_search`
`diskann-benchmark-core/src/search/graph/*.rs`	Updated benchmark code to use new search dispatch API
`Cargo.toml`, `Cargo.lock`	Version bump to 0.46.0 across all workspace crates

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diskann/src/graph/search/dispatch.rs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

This enables RecordedGraphSearch to implement SearchDispatch properly, since it holds &mut recorder which requires mutable access. - Change dispatch signature from &self to &mut self - Update index.search to take &mut P for search params - Implement SearchDispatch for RecordedGraphSearch - Remove apologetic comment about trait limitations - Update all callers to use &mut params

- RecordedGraphSearch in graph_search.rs - MultihopSearch in multihop_search.rs

narendatha · 2026-02-12T18:19:01Z

@microsoft-github-policy-service agree [company="Microsoft"] From: microsoft-github-policy-service[bot] ***@***.***> Sent: 12 February 2026 22:27 To: microsoft/DiskANN ***@***.***> Cc: Naren Datha ***@***.***>; Mention ***@***.***> Subject: Re: [microsoft/DiskANN] (RFC) Refactor search interface with unified SearchDispatch trait (PR #773) [https://avatars.githubusercontent.com/in/95686?s=20&v=4]microsoft-github-policy-service[bot] left a comment (microsoft/DiskANN#773)<#773 (comment)> @narendatha<https://github.com/narendatha> please read the following Contributor License Agreement(CLA). 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hildebrandmw

Thanks @narendatha! I think this does a good job of tying together the disparate APIs we've gathered. I'm pretty strongly in favor of getting rid of the legacy SearchParams and RangeSearchParams to avoid clutter, and updating the structs defined in this PR to not expose all the methods as public and therefore render the constructor invariant checks invalid.

diskann/src/graph/search/dispatch.rs

diskann/src/graph/search/diverse_search.rs

diskann/src/graph/search/range_search.rs

diskann/src/graph/index.rs

Cargo.toml

diskann-providers/src/index/diskann_async.rs

- Rename SearchDispatch trait to Search and move to mod.rs - Remove unnecessary doc comment about &mut self (can be inferred) - Remove 'feature-gated' mention from diverse_search.rs module doc - Fix banner styles to use ///// format instead of //=== - Make create_diverse_scratch an inherent method on DiverseSearch - Remove flat_search mention from index.search docs - Redirect debug_search to use RecordedGraphSearch internally - Revert version bump (0.46.0 -> 0.45.0) Co-authored-by: hildebrandmw <hildebrandmw@users.noreply.github.com>

narendatha · 2026-02-13T12:09:55Z

@microsoft-github-policy-service agree company="Microsoft"

…roUsize - Rename GraphSearch to KnnSearch for clarity (k-NN search) - Change k_value and l_value from usize to NonZeroUsize (compile-time zero check) - Rename RecordedGraphSearch to RecordedKnnSearch - Move RangeSearch validation from misc.rs to range_search.rs - Remove deprecated SearchParams, SearchParamsError, RangeSearchParams, RangeSearchParamsError - Update all callers across diskann, diskann-providers, diskann-disk, diskann-benchmark crates - Remove ensure_positive helper (no longer needed with NonZeroUsize) - Fix duplicated cfg attribute in diverse_search.rs

codecov-commenter · 2026-02-13T14:29:55Z

Codecov Report

❌ Patch coverage is 96.14792% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.00%. Comparing base (ea4078e) to head (6ce0d08).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...iskann-benchmark/src/backend/index/search/range.rs	0.00%	6 Missing ⚠️
diskann/src/graph/search/range_search.rs	97.65%	5 Missing ⚠️
diskann-providers/src/index/wrapped_async.rs	0.00%	3 Missing ⚠️
diskann/src/graph/search/multihop_search.rs	98.03%	3 Missing ⚠️
diskann-benchmark/src/backend/index/result.rs	50.00%	2 Missing ⚠️
diskann-benchmark/src/inputs/async_.rs	0.00%	2 Missing ⚠️
diskann-tools/src/utils/search_index_utils.rs	0.00%	2 Missing ⚠️
diskann-benchmark/src/backend/index/benchmarks.rs	0.00%	1 Missing ⚠️
diskann-benchmark/src/backend/index/search/knn.rs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #773      +/-   ##
==========================================
- Coverage   90.29%   89.00%   -1.29%     
==========================================
  Files         428      431       +3     
  Lines       78420    78446      +26     
==========================================
- Hits        70809    69822     -987     
- Misses       7611     8624    +1013

Flag	Coverage Δ
miri	`89.00% <96.14%> (-1.29%)`	⬇️
unittests	`89.00% <96.14%> (-1.29%)`	⬇️

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

Files with missing lines	Coverage Δ
diskann-benchmark-core/src/search/graph/knn.rs	`94.91% <100.00%> (+0.02%)`	⬆️
...iskann-benchmark-core/src/search/graph/multihop.rs	`98.69% <100.00%> (ø)`
diskann-benchmark-core/src/search/graph/range.rs	`93.70% <100.00%> (+0.18%)`	⬆️
diskann-benchmark/src/backend/index/spherical.rs	`100.00% <ø> (ø)`
diskann-disk/src/search/provider/disk_provider.rs	`91.01% <100.00%> (+0.02%)`	⬆️
diskann-providers/src/index/diskann_async.rs	`96.35% <100.00%> (+<0.01%)`	⬆️
diskann/src/error/ann_error.rs	`96.57% <ø> (-0.04%)`	⬇️
diskann/src/graph/index.rs	`95.91% <100.00%> (-0.55%)`	⬇️
diskann/src/graph/misc.rs	`80.00% <ø> (-14.60%)`	⬇️
diskann/src/graph/search/knn_search.rs	`100.00% <100.00%> (ø)`
... and 10 more

... and 63 files with indirect coverage changes

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…e diverse_search_experimental, use DiverseSearch + search() directly

hildebrandmw

Thanks @narendatha, I'm really liking how this is coming together!

diskann/src/graph/index.rs

diskann/src/graph/search/mod.rs

diskann/src/graph/search/knn_search.rs

diskann-benchmark/src/backend/index/search/knn.rs

- Rename dispatch() to search() in Search trait and all implementations - Reorder DiskANNIndex::search params: search_params now first argument - KnnSearch::new takes usize instead of NonZeroUsize (with KZero/LZero errors) - Change beam_width from Option<usize> to Option<NonZeroUsize> - Add #[track_caller] to From<KnnSearchError> and From<RangeSearchError> - Make DiverseSearch fields private with accessor methods - Remove unused nz() helper functions - Update all callers across workspace

…iverseSearch->Diverse Drop 'Search' suffix from main search parameter types: - KnnSearch -> Knn - RangeSearch -> Range - DiverseSearch -> Diverse - RecordedKnnSearch -> RecordedKnn Error types and output types retain their names: - KnnSearchError (unchanged) - RangeSearchError, RangeSearchOutput (unchanged) - DiverseSearchParams (unchanged)

Search parameter types must now be accessed via graph::search:: - graph::search::Knn (was graph::Knn) - graph::search::Range (was graph::Range) - graph::search::Diverse (was graph::Diverse) - graph::search::RecordedKnn (was graph::RecordedKnn) - graph::search::MultihopSearch (was graph::MultihopSearch) The Search trait and error types remain at graph:: level: - graph::Search - graph::KnnSearchError - graph::RangeSearchError - graph::RangeSearchOutput

- Move detailed algorithm docs from impl block to struct Knn - Add implementation list to Search trait directing users to specific types

Change Search trait and DiskANNIndex::search to consume search params by value: - fn search(&mut self, ...) -> fn search(self, ...) - Callers no longer need &mut references - Removes unnecessary mut declarations at call sites - Knn, Range, etc. are Copy so no overhead from pass-by-value This simplifies the API and makes the intent clearer - search params are consumed, not modified and reused.

narendatha requested review from a team and Copilot February 12, 2026 16:55

narendatha changed the title ~~Refactor search interface with unified SearchDispatch trait~~ (RFC) Refactor search interface with unified SearchDispatch trait Feb 12, 2026

Copilot started reviewing on behalf of narendatha February 12, 2026 16:56 View session

Copilot AI reviewed Feb 12, 2026

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diskann/src/graph/search/dispatch.rs Outdated Show resolved Hide resolved

narendatha and others added 4 commits February 12, 2026 22:39

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77e6677

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

refactor: replace manual Debug impls with derive

dbd3481

- RecordedGraphSearch in graph_search.rs - MultihopSearch in multihop_search.rs

style: cargo fmt

caac0f0

hildebrandmw reviewed Feb 13, 2026

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narendatha added 2 commits February 13, 2026 21:18

Add documentation to Search trait and KnnSearch dispatch methods

33b2158

Remove debug_search, use RecordedKnnSearch + search() directly; Remov…

5e81b35

…e diverse_search_experimental, use DiverseSearch + search() directly

hildebrandmw requested changes Feb 13, 2026

View reviewed changes

narendatha added 6 commits February 14, 2026 15:42

fix: correct remaining search param ordering in test files

3615079

docs: move Knn docs to struct level and improve Search trait docs

b3bb9ce

- Move detailed algorithm docs from impl block to struct Knn - Add implementation list to Search trait directing users to specific types

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narendatha commented Feb 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Refactor search interface with unified SearchDispatch trait

Summary

Changes

New Architecture

API Changes

Code Organization

Other

Usage Example

Why flat_search is not included

Testing

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narendatha commented Feb 12, 2026 •

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