[SVS] Implement 2-stage backend SVS index initialization by rfsaliev · Pull Request #903 · RedisAI/VectorSimilarity

rfsaliev · 2026-02-02T14:06:59Z

Purpose: prevent long time SVS Tiered index lock at initialization time.

Logic:

First stage: create svs::...::MutableVamanaIndex instance with R/O shared lock
Second stage: set svs::...::MutableVamanaIndex created before under R/W unique lock

Which issues this PR fixes

#7831

Main objects this PR modified

2 methods added to SVSIndex: createImpl() and setImpl()
SVSTiered update job is modified to call createImpl() under shared lock and setImpl() under unique lock if backend index is empty.

Mark if applicable

This PR introduces API changes
This PR introduces serialization changes

Purpose: prevent long time SVS Tiered index lock at initialization time. Logic: First stage: create `svs::...::MutableVamanaIndex` instance with R/O shared lock Second stage: set `svs::...::MutableVamanaIndex` created before under R/W unique lock

jit-ci · 2026-02-02T14:07:08Z

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codecov · 2026-02-02T14:29:59Z

Codecov Report

❌ Patch coverage is 96.55172% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.08%. Comparing base (bd3769b) to head (616b4ba).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/VecSim/algorithms/svs/svs.h	94.11%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #903      +/-   ##
==========================================
- Coverage   97.09%   97.08%   -0.01%     
==========================================
  Files         129      129              
  Lines        7493     7541      +48     
==========================================
+ Hits         7275     7321      +46     
- Misses        218      220       +2

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…d index.

alonre24

LGTM!
A few small comments.
Also please:

Validate that covering the affected scenarios in unit tests (I believe we are)
Add micro benchmarks that will prove the improvement (add vector/run query while initial index creation is executed in the background)

alonre24 · 2026-02-09T17:43:42Z

src/VecSim/algorithms/svs/svs.h

+    }
+
+    void setImpl(std::unique_ptr<ImplHandler> handler) override {
+        assert(handler && "SVSIndex::setImpl called with null handler");


If this is a debug-only assert, let's add this to the log in a warning level as well

This assert is added just to simplify logic error catching in DEBUG mode - as well as the next-line assert.
In release mode, the logic_error will be thrown later if handler is null.

assert()s here are not really needed - except for debugging purposes.
I can just remove them.

alonre24 · 2026-02-09T18:23:25Z

src/VecSim/algorithms/svs/svs.h

+        std::span<const labelType> ids(labels, n);
+        auto processed_blob = this->preprocessForBatchStorage(vectors_data, n);
+        auto typed_vectors_data = static_cast<DataType *>(processed_blob.get());
+        // Wrap data into SVS SimpleDataView for SVS API
+        auto points = svs::data::SimpleDataView<DataType>{typed_vectors_data, n, this->dim};
+


This logic seems to be a duplication of what we do in addVectorsImpl. Consider unifying these into a single function

The main point here is the processed_blob which lifetime should be managed till end of initImpl() and impl_->add_points() calls.
A single function, which will wrap all this code would look like:

std::tuple<std::span<const labelType>, MemoryUtils::unique_blob, svs::data::SimpleDataView<DataType>> preprocessAndPrepareSVSArgs(...)

alonre24 · 2026-02-09T18:36:03Z

src/VecSim/algorithms/svs/svs.h

+        SVSImplHandler *svs_handler = dynamic_cast<SVSImplHandler *>(handler.get());
+        if (!svs_handler) {
+            throw std::logic_error("Failed to cast to SVSImplHandler");
+        }


What is the motivation to have an abstract ImplHandler rather than have only SVSImplHandler? The dynamic_cast here seems a bit awkward

SVSImplHandler is not just a simple type - it is template class with a number of parameters, and it's full declaration looks like:

template <typename MetricType, typename DataType, bool isMulti, size_t QuantBits, size_t ResidualBits, bool IsLeanVec> struct SVSIndex<MetricType, DataType, isMulti, QuantBits, ResidualBits, IsLeanVec>::SVSImplHandler;

This why the abstract SVSIndexBase::ImplHandler is defined for client code (TieredSVSIndex).

meiravgri · 2026-02-10T14:55:51Z

src/VecSim/algorithms/svs/svs_tiered.h

-            svs_index->setNumThreads(std::min(availableThreads, labels_to_move.size()));
-            svs_index->addVectors(vectors_to_move.data(), labels_to_move.data(),
-                                  labels_to_move.size());
+            if (this->backendIndex->indexSize() == 0) {


Does this also handle re-initialization after the index was emptied? Is that scenario tested?

Yes, as it was before in SVSIndex::AddVectors()

rfsaliev requested review from alonre24 and meiravgri February 2, 2026 14:06

Avoid unique locking for deletion of non-existing vectors from backen…

616b4ba

…d index.

alonre24 reviewed Feb 9, 2026

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meiravgri reviewed Feb 10, 2026

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[SVS] Implement 2-stage backend SVS index initialization#903

[SVS] Implement 2-stage backend SVS index initialization#903
rfsaliev wants to merge 2 commits intomainfrom
rfsaliev/svs-async-create-impl

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