feat: add hierarchy flag to LSM vector index configuration by robfrank · Pull Request #3130 · ArcadeData/arcadedb

robfrank · 2026-01-14T13:17:21Z

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gemini-code-assist · 2026-01-14T13:17:41Z

Summary of Changes

Hello @robfrank, 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 enhances the LSM vector index by introducing a new addHierarchy configuration option. This flag provides fine-grained control over the underlying Hierarchical Navigable Small World (HNSW) graph structure, enabling users to decide whether to include hierarchical layers. This feature offers flexibility in balancing search performance, index size, and build time, allowing for better optimization based on specific application requirements.

Highlights

New Configuration Flag: Introduced an addHierarchy boolean flag to the LSM vector index configuration, allowing control over the creation of hierarchical layers in the HNSW graph.
Index Builder and Metadata Integration: The addHierarchy flag has been integrated into LSMVectorIndexMetadata, BucketLSMVectorIndexBuilder, and TypeLSMVectorIndexBuilder to ensure it can be configured during index creation and persisted in metadata.
Core Index Logic Update: The LSMVectorIndex now utilizes the addHierarchy flag when constructing the GraphIndexBuilder, directly influencing the HNSW graph structure.
Test Coverage: Updated existing tests to include the new addHierarchy configuration, demonstrating its usage both via JSON and programmatic index creation.

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mergify · 2026-01-14T13:18:41Z

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robfrank · 2026-01-14T13:19:11Z

@tae898 I've added the flag. It was set to false as default value. What value is better as default one, in your opinion?

gemini-code-assist

Code Review

This pull request introduces an addHierarchy flag to the LSM vector index configuration, which controls the creation of hierarchical HNSW graphs. The changes are correctly propagated through the metadata and builder classes, and new tests are included to validate the functionality. My review identified a potential NullPointerException in a new builder method and an inconsistent default value for the new flag across different builder classes. Addressing these points will improve the robustness and predictability of the new feature.

engine/src/main/java/com/arcadedb/schema/TypeLSMVectorIndexBuilder.java

engine/src/main/java/com/arcadedb/schema/BucketLSMVectorIndexBuilder.java

…lder.java Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

…uilder.java Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

lvca · 2026-01-14T13:38:39Z

engine/src/main/java/com/arcadedb/schema/LSMVectorIndexMetadata.java

+  public int                      graphBuildCacheSize      = -1; // -1 = use global default
+  public int                      mutationsBeforeRebuild   = -1; // -1 = use global default
+  public boolean                  storeVectorsInGraph      = false; // Phase 2: Store vectors inline in graph file
+  public boolean                  addHierarchy             = true;


Shouldn't be false by default? Or this is always the reccommended seting?

It was false, I've asked to @tae898 in the previous comment. Mybe true is better? I don't know :)

didn't jvector set this true by defualt?

Setting the addHierarchy parameter to true, build a multi-layer index. This approach has proven more robust in highly challenging scenarios. https://github.com/datastax/jvector

I mean ofc I do wanna try both tho and compare.

codacy-production · 2026-01-14T13:48:44Z

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ -0.18%	✅ 85.71%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (`64e6015`)	76651	49983	65.21%
Head commit (`2dc7bec`)	76666 (+15)	49856 (-127)	65.03% (-0.18%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#3130)	126	108	85.71%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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* feat: add hierarchy flag to LSM vector index configuration * Update engine/src/main/java/com/arcadedb/schema/TypeLSMVectorIndexBuilder.java Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com> * Update engine/src/main/java/com/arcadedb/schema/BucketLSMVectorIndexBuilder.java Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com> * fix: disable hierarchy flag in vector index metadata --------- Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com> (cherry picked from commit aa82f86)

feat: add hierarchy flag to LSM vector index configuration

ba2918d

robfrank linked an issue Jan 14, 2026 that may be closed by this pull request

Expose JVector addHierarchy option in ArcadeDB vector index #3127

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robfrank added this to the 26.1.1 milestone Jan 14, 2026

gemini-code-assist bot reviewed Jan 14, 2026

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engine/src/main/java/com/arcadedb/schema/TypeLSMVectorIndexBuilder.java Outdated Show resolved Hide resolved

engine/src/main/java/com/arcadedb/schema/BucketLSMVectorIndexBuilder.java Outdated Show resolved Hide resolved

robfrank and others added 2 commits January 14, 2026 05:20

Update engine/src/main/java/com/arcadedb/schema/TypeLSMVectorIndexBui…

e737c9e

…lder.java Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Update engine/src/main/java/com/arcadedb/schema/BucketLSMVectorIndexB…

dd56ec5

…uilder.java Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

lvca reviewed Jan 14, 2026

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lvca assigned robfrank Jan 14, 2026

lvca added the enhancement New feature or request label Jan 14, 2026

fix: disable hierarchy flag in vector index metadata

2dc7bec

lvca merged commit aa82f86 into main Jan 14, 2026
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feat: add hierarchy flag to LSM vector index configuration#3130

feat: add hierarchy flag to LSM vector index configuration#3130
lvca merged 4 commits intomainfrom
feat/3127-add-jvector-hierarchy-flag

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