[Mark Hildebrand (hildebrandmw)]

DataProvider::to_external_id is apparently not used anywhere in the core algorithm. There are currently two users of internal to external ID translation:

• diskann-garnert: Just uses it for post-processing and works just fine with to_external_id as an inherent method on GarnetProvider.
• diskann-inmem: Does do ID translation, but already uses a more batch-friendly version during its post-processing.

Removing this (outside of removing code that doesn't apparently have a need) helps the diskann-inmem work as we don't need to provide an extremely slow fallback if ID translation is moved behind the epoch protected boundary.

[Copilot]

🟢 Approval recommended

There are no active review issues for the removal of the unused DataProvider::to_external_id trait method.

No open issues 🎉

What changed in this PR

Removes the unused DataProvider::to_external_id trait method, leaving internal-to-external ID translation to provider-specific post-processing. This simplifies the core interface and avoids requiring a slow fallback for future epoch-protected translation in diskann-inmem.

Changes:

• Remove the trait method and its implementations across providers.
• Preserve Garnet’s translation logic as a private inherent method.
• Remove test assertions for the deleted API.

File	Description
diskann/​src/​provider.rs	Remove to_external_id from the core trait.
diskann/​src/​graph/​test/​provider.rs	Remove the test provider’s implementation and related assertions.
diskann/​src/​flat/​test/​provider.rs	Remove the test provider’s implementation.
diskann-providers/​src/​model/​graph/​provider/​async_/​inmem/​provider.rs	Remove identity translation and its test assertion.
diskann-label-filter/​src/​encoded_attribute_provider/​document_provider.rs	Remove forwarding of the deleted method.
diskann-inmem/​src/​provider.rs	Remove single-ID reverse translation and related assertions.
diskann-garnet/​src/​provider.rs	Move reverse translation into an inherent method.
diskann-disk/​src/​search/​provider/​disk_provider.rs	Remove identity translation and its test assertion.
diskann-bftree/​src/​provider.rs	Remove identity translation and its test assertion.

_{Review effort: Balanced}

[Codecov Comments Bot (codecov-commenter)]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.02%. Comparing base (413be59) to head (e3bc17e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1541      +/-   ##
==========================================
+ Coverage   91.01%   91.02%   +0.01%     
==========================================
  Files         602      602              
  Lines      124144   124080      -64     
==========================================
- Hits       112994   112949      -45     
+ Misses      11150    11131      -19     

Flag	Coverage Δ
miri	91.02% <100.00%> (+0.01%)	⬆️
unittests	90.73% <100.00%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
diskann-bftree/src/provider.rs	93.95% <ø> (-0.03%)	⬇️
diskann-disk/src/search/provider/disk_provider.rs	95.90% <ø> (-0.04%)	⬇️
diskann-garnet/src/provider.rs	90.18% <100.00%> (+0.08%)	⬆️
diskann-inmem/src/provider.rs	96.19% <ø> (-0.10%)	⬇️
...rc/encoded_attribute_provider/document_provider.rs	0.00% <ø> (ø)
.../src/model/graph/provider/async_/inmem/provider.rs	92.36% <ø> (-0.21%)	⬇️
diskann/src/flat/test/provider.rs	71.21% <ø> (+2.59%)	⬆️
diskann/src/graph/test/provider.rs	95.34% <ø> (-0.05%)	⬇️
diskann/src/provider.rs	98.18% <ø> (ø)

... and 4 files with indirect coverage changes

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