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…ion (#293) The Weaviate gRPC protocol only supports fp32 (SingleFp32/MultiFp32), but ToByteString(this Vector) was serializing the backing data using its native byte width (8 bytes for double, 8 bytes for long, etc.). When a user provided a double[] vector of dimension 1536, the server received 12288 bytes labelled as SingleFp32 and interpreted them as 3072 floats — doubling the dimension with garbled NaN values. The fix converts all non-float numeric types to float32 before byte serialisation in both ToByteString() and ToMultiDimensionalByteString(). The single REST insert path was unaffected (JSON serialisation handles doubles natively); only the gRPC batch path and vector-search path were buggy. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary - Weaviate C# Client CoverageSummary
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dirkkul
approved these changes
Mar 2, 2026
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Summary
Fixes #293 — batch
InsertManywith non-floatself-provided vectors (e.g.double[]) produced double the expected dimension with NaN values on retrieval.Root cause:
ToByteString(this Vector)inExtensions.csserialised backing data using its native byte width (8 bytes fordouble). The Weaviate gRPC protocol only supportsfp32(SingleFp32/MultiFp32). Sending1536 × 8 = 12288bytes labelled asSingleFp32caused the server to interpret them as3072floats with garbled NaN values.Fix: Convert all non-
floatnumeric vector types tofloat32before byte serialisation in bothToByteString()andToMultiDimensionalByteString(). The single REST insert path is unaffected (JSON serialises doubles natively).Scope: Also fixes the same bug in the vector-search path (
Search.Builders.cs) since it calls the sameToByteString()extension.Changes
src/Weaviate.Client/Extensions.cs—ToByteStringandToMultiDimensionalByteStringnow always emit float32 bytes for all numeric vector typessrc/Weaviate.Client.Tests/Unit/TestVectorData.cs— 5 new unit tests verifying the byte-length contract (N elements × 4 bytes) and value correctnessTest Plan
Expected: 12, Actual: 24)