improvement: performance of update vector

[ShawnShawnYou]

close #1288

Summary by Sourcery

Enhancements:

• Replace KNN-based neighbor search with direct neighbor list retrieval in update_vector for both HNSW and HGraph to reduce data copy and search overhead

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Replaces expensive dataset copy and knn search in update_vector for both HNSW and HGraph with direct neighbor retrieval APIs, reducing overhead and boosting performance.

Sequence diagram for optimized neighbor retrieval in update_vector

sequenceDiagram
participant HNSW
participant HNSWLib
HNSW->>HNSWLib: get_linklist0(id)
HNSW->>HNSWLib: getListCount(linklist)
loop For each neighbor
    HNSW->>HNSWLib: getDistanceByLabel(neighbor_id, new_base_vec)
end

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Sequence diagram for optimized neighbor retrieval in HGraph::UpdateVector

sequenceDiagram
participant HGraph
participant BottomGraph
HGraph->>BottomGraph: GetNeighbors(inner_id, neighbors)
loop For each neighbor
    HGraph->>HGraph: CalcDistanceById(new_base_vec, neighbor_id)
end

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Class diagram for updated neighbor retrieval in HNSW and HGraph

classDiagram
class HNSW {
  +update_vector(id, new_base, force_update)
}
class HNSWLib {
  +get_linklist0(id)
  +getListCount(linklist)
  +getDistanceByLabel(id, vec)
}
HNSW --> HNSWLib

class HGraph {
  +UpdateVector(id, new_base, force_update)
  -bottom_graph_: BottomGraph
}
class BottomGraph {
  +GetNeighbors(inner_id, neighbors)
}
HGraph --> BottomGraph

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File-Level Changes

Change	Details	Files
Optimize HNSW update_vector by eliminating dataset copy and knn search in favor of direct neighbor link retrieval	Removed base_data allocation and dataset construction Removed knn_search and neighbor result handling Used get_linklist0 and getListCount to fetch neighbors Iterated direct neighbor IDs for distance comparison	src/index/hnsw.cpp
Optimize HGraph UpdateVector by replacing knn search with direct bottom_graph neighbor retrieval	Removed base_data allocation and dataset setup Removed KnnSearch invocation Called bottom_graph_->GetNeighbors for neighbor list Iterated over neighbors vector for distance checks	src/algorithm/hgraph.cpp

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#1288	Improve the performance of the update_vector function in the codebase.	✅

Possibly linked issues

• improve performance of update vector #1288: The PR optimizes neighbor access in update_vector, directly addressing the performance issue.

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[gemini-code-assist]

Summary of Changes

Hello @ShawnShawnYou, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the performance of vector update operations within the HGraph and HNSW indexing algorithms. By streamlining the process of identifying existing neighbors, it significantly reduces computational overhead and improves the efficiency of updating vectors in the index.

Highlights

• Performance Improvement: Optimized the UpdateVector function in both HGraph and HNSW by replacing k-NN searches for neighbor retrieval with direct access to the graph's existing neighborhood information.
• Reduced Computational Overhead: Eliminated the need to create temporary Dataset objects and perform potentially costly search operations during vector updates, leading to more efficient processing.

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[sourcery-ai]

Hey there - I've reviewed your changes and they look great!

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[gemini-code-assist]

Code Review

This pull request aims to improve the performance of UpdateVector by replacing KNN search with direct neighbor retrieval from the graph. This is a good optimization.

My review has identified a critical issue in hnsw.cpp and a high-severity issue in hgraph.cpp. Both are related to incorrect handling of internal vs. external IDs, which could lead to incorrect behavior or crashes. Please see the detailed comments for suggestions on how to fix them.

[wxyucs]

lgtm

[codecov]

Codecov Report

❌ Patch coverage is 84.90566% with 8 lines in your changes missing coverage. Please review.

@@            Coverage Diff             @@
##             main    #1289      +/-   ##
==========================================
+ Coverage   91.42%   92.02%   +0.60%     
==========================================
  Files         318      320       +2     
  Lines       17622    17687      +65     
==========================================
+ Hits        16111    16277     +166     
+ Misses       1511     1410     -101     

Flag	Coverage Δ
cpp	92.02% <84.90%> (+0.60%)	⬆️

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

Components	Coverage Δ
common	91.15% <ø> (-0.63%)	⬇️
datacell	93.27% <ø> (+0.29%)	⬆️
index	91.04% <84.61%> (+0.59%)	⬆️
simd	100.00% <ø> (ø)

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[inabao]

LGTM

[wxyucs]

@ShawnShawnYou this pull request cannot cherry-pick to the branch 0.16 (CONFLICT), please create a new pull request to the branch 0.16.