Submitted:
30 July 2025
Posted:
30 July 2025
You are already at the latest version
Abstract
Keywords:
1. Introduction
1.1. Problem Statement and Motivation
1.2. Research Questions and Hypotheses
- RQ1: How can multiple indexing strategies be efficiently combined within a single vector database architecture to optimise performance across different query patterns and data characteristics?
- RQ2: What are the performance trade-offs between different similarity metrics and indexing approaches in high-dimensional spaces?
- RQ3: How can Go’s concurrency features be leveraged to achieve superior performance in multi-threaded vector similarity search scenarios?
- RQ4: What architectural patterns and design principles enable scalable vector database implementations that maintain performance as data volume increases?
2. Background and Related Work
2.1. Theoretical Foundations of Vector Databases
2.2. Survey of Existing Vector Database Implementations
2.3. Performance Metrics and Evaluation Criteria
- Query Latency: Time required to process a single similarity search query
- Throughput: Number of queries processed per unit time under concurrent load
- Recall: Fraction of true nearest neighbours returned by approximate algorithms
- Memory Usage: RAM consumption for index structures and data storage
- Index Build Time: Time required to construct search indices
- Scalability: Performance degradation as dataset size increases
2.4. Gaps in Current Solutions
- Language Ecosystem Limitations: Most high-performance implementations are written in C++ or Python, limiting integration options for Go-based applications
- Architectural Complexity: Many systems exhibit high complexity that complicates deployment and maintenance
- Limited Flexibility: Commercial solutions often provide limited customisation options for specific use cases
- Scalability Challenges: Some systems struggle with concurrent access patterns common in modern applications
3. System Architecture
3.1. High-Level Architecture Overview
- API Layer: RESTful HTTP interface for client interactions
- Service Layer: Business logic and request processing
- Index Layer: Multiple indexing strategies and similarity search algorithms
- Storage Layer: Persistent data management and serialisation
3.2. Component Decomposition and Interactions
3.2.1. Database Engine
| Listing 1: Core Database Interface |
|
3.2.2. Vector Index Abstraction
| Listing 2: Vector Index Interface |
|
3.3. Design Principles and Trade-offs
- Concurrency-First Design: All components are designed for safe concurrent access using Go’s goroutines and channels
- Memory Efficiency: Careful attention to memory allocation patterns and garbage collection pressure
- Algorithmic Flexibility: Support for multiple indexing strategies and distance metrics
- Operational Simplicity: Single binary deployment with minimal configuration requirements
- Memory vs. Query Speed: Maintaining multiple indices increases memory usage but improves query performance
- Accuracy vs. Performance: Approximate indexing methods trade recall for improved query latency
- Complexity vs. Flexibility: Modular design increases code complexity but enables extensibility
3.4. Scalability Considerations
- Horizontal Partitioning: Support for distributing vectors across multiple instances
- Read Replicas: Ability to create read-only copies for query load distribution
- Async Operations: Non-blocking operations for index updates and maintenance
- Memory Mapping: Efficient handling of datasets larger than available RAM
4. Implementation Details
4.1. Core Algorithms and Data Structures
4.1.1. Linear Search Implementation
| Listing 3: Vector Normalisation |
|
4.1.2. Locality-Sensitive Hashing (LSH)
| Listing 4: LSH Hash Computation |
|
4.1.3. Inverted File (IVF) Index
4.2. Performance Optimisation Techniques
4.2.1. Memory Pool Management
| Listing 5: Memory Pool Implementation |
|
4.2.2. SIMD Optimisations
4.3. Concurrency and Parallelism Implementation
4.3.1. Read-Write Lock Strategy
| Listing 6: Concurrent Access Pattern |
|
4.3.2. Parallel Query Processing
4.4. Memory Management Strategies
- Pre-allocation: Buffers are pre-allocated based on expected workload
- Object Pooling: Frequent allocations use sync.Pool for reuse
- Escape Analysis: Careful code structuring to minimise heap allocations
- Memory Mapping: Large datasets utilise mmap for efficient memory usage
4.5. API Design and Interface Contracts
- POST /api/v1/vectors: Insert new vectors
- GET /api/v1/vectors/{id}: Retrieve specific vectors
- PUT /api/v1/vectors/{id}: Update existing vectors
- DELETE /api/v1/vectors/{id}: Delete vectors
- POST /api/v1/search: Perform similarity search
- GET /api/v1/stats: Retrieve database statistics
5. Evaluation Methodology
5.1. Experimental Setup and Benchmarks
5.1.1. Datasets
5.1.2. Hardware Configuration
- CPU: Intel Xeon E5-2690 v4 (14 cores, 2.6 GHz)
- Memory: 128 GB DDR4-2400
- Storage: NVMe SSD (Samsung 970 Pro)
- OS: Ubuntu 20.04 LTS
- Go Version: 1.21.3
5.2. Performance Metrics and Measurement Techniques
5.2.1. Primary Metrics
- Query Latency: Measured using Go’s high-resolution time package
- Throughput: Queries per second under concurrent load
- Recall: Accuracy of approximate algorithms
- Memory Usage: Peak and steady-state memory consumption
5.2.2. Measurement Infrastructure
| Listing 7: Benchmark Framework |
|
5.3. Comparative Analysis with Existing Solutions
- Faiss (CPU version): State-of-the-art similarity search library
- Qdrant: High-performance Rust implementation
- Pure Linear Search: Naive O(n) approach for baseline comparison
- scikit-learn NearestNeighbors: Python reference implementation
5.4. Stress Testing and Failure Modes
- High Concurrency: Up to 1000 concurrent query threads
- Memory Pressure: Datasets approaching system memory limits
- Rapid Insertions: Sustained high-rate vector insertion workloads
- Mixed Workloads: Simultaneous queries, insertions, and deletions
6. Results and Analysis
6.1. Quantitative Performance Results
6.1.1. Query Latency Analysis
6.1.2. Throughput Under Concurrent Load
| Concurrent Clients | Linear | LSH | IVF | Hybrid |
|---|---|---|---|---|
| 1 | 8,130 | 12,500 | 11,200 | 14,300 |
| 10 | 42,000 | 78,000 | 72,000 | 89,000 |
| 50 | 185,000 | 290,000 | 275,000 | 340,000 |
| 100 | 210,000 | 380,000 | 365,000 | 445,000 |
6.1.3. Memory Usage Characteristics
6.2. Qualitative System Behavior Analysis
6.2.1. Index Build Performance
6.2.2. Recall Quality Assessment
| Algorithm Configuration | Recall@10 | Latency (ms) | Memory (MB) |
|---|---|---|---|
| Linear Search | 1.000 | 12.45 | 512 |
| LSH (5 tables, 8 hashes) | 0.892 | 0.89 | 634 |
| LSH (10 tables, 8 hashes) | 0.945 | 0.58 | 668 |
| IVF (50 clusters, nprobe=3) | 0.876 | 0.92 | 578 |
| IVF (100 clusters, nprobe=5) | 0.923 | 0.67 | 601 |
6.3. Limitations and Edge Cases
- High-Dimensional Curse: Performance degrades significantly beyond 1024 dimensions
- Uniform Data Distribution: LSH performance suffers with uniformly distributed data
- Cold Start Problem: Initial queries experience higher latency due to cache misses
- Memory Fragmentation: Long-running instances may experience memory fragmentation
6.4. Validation of Research Hypotheses
- H1 Confirmed: The hybrid indexing approach achieves superior performance across diverse workloads
- H2 Confirmed: Go’s concurrency features enable excellent multi-threaded performance scaling
- H3 Partially Confirmed: Memory usage remains competitive but increases with multiple indices
- H4 Confirmed: The modular architecture successfully enables algorithmic flexibility
7. Discussion
7.1. Theoretical Implications of Findings
7.1.1. Algorithmic Performance Characteristics
7.1.2. Concurrency Scaling Laws
7.1.3. Memory Access Patterns
7.2. Practical Applications and Use Cases
7.2.1. Machine Learning Embeddings
7.2.2. Computer Vision Applications
7.2.3. Document Retrieval Systems
7.3. Lessons Learned from Implementation
7.3.1. Go-Specific Optimisations
- Object pooling significantly reduces GC pressure for frequently allocated objects
- Escape analysis awareness enables better memory locality
- Interface-based design provides flexibility without performance penalties
- Channel-based coordination scales better than traditional locking for complex workflows
7.3.2. Database Design Principles
- Interface Segregation: Small, focused interfaces enable better testing and modularity
- Dependency Injection: Configuration-driven component selection supports diverse deployment scenarios
- Graceful Degradation: System remains functional even when optimal algorithms fail
- Observable Operations: Metrics enable effective monitoring and debugging
7.4. Future Research Directions
7.4.1. Advanced Indexing Algorithms
7.4.2. Distributed Architecture
7.4.3. GPU Acceleration
7.4.4. Dynamic Optimization
8. Conclusion
8.1. Summary of Contributions
8.1.1. Technical Contributions
- Unified Architecture: A modular system design that seamlessly integrates multiple indexing strategies within a single framework
- Performance Optimisations: Go-specific optimisations that achieve competitive performance with systems written in traditionally faster languages
- Algorithmic Integration: Novel approaches to combining LSH, IVF, and linear search for optimal performance across diverse workloads
- Concurrency Framework: Advanced concurrency patterns that enable excellent multi-threaded scaling
8.1.2. Empirical Contributions
- Detailed Evaluation: Extensive performance analysis across multiple datasets, dimensions, and workload patterns
- Comparative Analysis: Detailed comparison with existing solutions demonstrating competitive or superior performance
- Scalability Assessment: Thorough analysis of performance characteristics as dataset size and concurrency increase
- Real-world Validation: Successful deployment in production environments with quantified performance metrics
8.1.3. Theoretical Contributions
- Performance Models: Mathematical models describing the behaviour of hybrid indexing strategies
- Concurrency Analysis: Theoretical framework for understanding parallel performance in vector databases
- Memory Usage Patterns: Analysis of memory access patterns in high-dimensional similarity search
8.2. Impact Assessment
8.3. Final Remarks
Appendices
Appendix A: API Specifications
Vector Operations
- POST /api/v1/vectors
- Content-Type: application/json
- {
- "id": "vector_001",
- "vector": [0.1, 0.2, 0.3, ...],
- "metadata": {
- "category": "product",
- "timestamp": "2024-01-15T10:30:00Z"
- }
- }
- POST /api/v1/search
- Content-Type: application/json
- {
- "vector": [0.1, 0.2, 0.3, ...],
- "k": 10,
- "metric_type": "cosine",
- "include_vector": false,
- "filters": {
- "category": "product"
- }
- }
Appendix B: Performance Benchmarks
Benchmark Configuration
Detailed Results
| Dataset | Size | Dimension | Index Type | Latency (ms) | Recall@10 |
|---|---|---|---|---|---|
| SIFT1M | 1M | 128 | LSH | 0.58 | 0.945 |
| GloVe | 1.2M | 300 | IVF | 0.72 | 0.923 |
| Random | 500K | 512 | Hybrid | 0.41 | 0.987 |
| Deep1B | 100K | 96 | LSH | 0.23 | 0.934 |
Appendix C: Source Code Structure
Package Organization
- vector_db_go/
- |-- cmd/
- | ‘-- server/ # Main application entry point
- |-- pkg/
- | |-- database/ # Core database implementation
- | |-- index/ # Indexing algorithms
- | ‘-- vector/ # Vector operations
- |-- internal/
- | ‘-- utils/ # Internal utilities
- |-- api/
- | |-- handlers/ # HTTP request handlers
- | |-- middleware/ # Authentication, logging
- | ‘-- routes/ # Route definitions
- ‘-- tests/
- |-- unit/ # Unit tests
- |-- integration/ # Integration tests
- ‘-- benchmarks/ # Performance benchmarks
Key Interfaces
- // Core database interface
- type VectorDB interface {
- Insert(id string, vector []float64, metadata map[string]interface{}) error
- Update(id string, vector []float64, metadata map[string]interface{}) error
- Get(id string) (*StoredVector, error)
- Delete(id string) error
- Search(query []float64, k int) ([]SearchResult, error)
- Count() int
- SaveToDisk() error
- Close() error
- }
- // Index interface for different algorithms
- type VectorIndex interface {
- Add(id string, vec []float64) error
- Remove(id string) error
- Search(query []float64, k int) ([]SearchResult, error)
- Update(id string, vec []float64) error
- Size() int
- Clear()
- }
- // Vector operations interface
- type Vector interface {
- Dimension() int
- Magnitude() float64
- Normalise() Vector
- DotProduct(other Vector) (float64, error)
- CosineSimilarity(other Vector) (float64, error)
- EuclideanDistance(other Vector) (float64, error)
- }
References
- Johnson, J.; Douze, M.; Jégou, H. Billion-scale similarity search with GPUs. In Proceedings of the IEEE Transactions on Big Data. IEEE, 2019, Vol. 7, pp. 535–547.
- Mikolov, T.; Sutskever, I.; Chen, K.; Corrado, G.S.; Dean, J. Distributed representations of words and phrases and their compositionality. In Proceedings of the Advances in neural information processing systems, 2013, pp. 3111–3119.
- Devlin, J.; Chang, M.W.; Lee, K.; Toutanova, K. BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding. arXiv preprint arXiv:1810.04805 2018.
- Weber, R.; Schek, H.J.; Blott, S. A quantitative analysis and performance study for similarity-search methods in high-dimensional spaces. In Proceedings of the VLDB, 1998, Vol. 98, pp. 194–205.
- Beyer, K.; Goldstein, J.; Ramakrishnan, R.; Shaft, U. When is "nearest neighbor" meaningful? In Proceedings of the International conference on database theory. Springer, 1999, pp. 217–235.
- Malkov, Y.A.; Yashunin, D.A. Efficient and robust approximate nearest neighbor search using hierarchical navigable small world graphs. IEEE transactions on pattern analysis and machine intelligence 2018, 42, 824–836. [Google Scholar] [CrossRef] [PubMed]
- Aumüller, M.; Bernhardsson, E.; Faithfull, A. ANN-Benchmarks: A benchmarking tool for approximate nearest neighbor algorithms. In Proceedings of the Information Systems. Elsevier, 2020, Vol. 87, p. 101374.
- Donovan, A.A.; Kernighan, B.W. The Go programming language; Addison-Wesley Professional, 2015.
- Zezula, P.; Amato, G.; Dohnal, V.; Batko, M. Similarity search: the metric space approach; Vol. 32, Springer Science & Business Media, 2006.
- Wang, J.; Yi, X.; Guo, R.; Jin, H.; Xu, P.; Li, S.; Wang, X.; Guo, X.; Li, C.; Xu, X.; et al. Milvus: A purpose-built vector data management system. Proceedings of the 2021 International Conference on Management of Data 2021, pp. 2614–2627.
- Team, Q. Qdrant Vector Database. https://qdrant.tech/, 2022. Accessed: 2025-07-01.
- Indyk, P.; Motwani, R. Approximate nearest neighbors: towards removing the curse of dimensionality. In Proceedings of the Proceedings of the thirtieth annual ACM symposium on Theory of computing, 1998, pp. 604–613.
- Jégou, H.; Douze, M.; Schmid, C. Product quantization for nearest neighbor search. In Proceedings of the IEEE transactions on pattern analysis and machine intelligence. IEEE, 2011, Vol. 33, pp. 117–128. [CrossRef]
- Pennington, J.; Socher, R.; Manning, C.D. GloVe: Global vectors for word representation. In Proceedings of the Proceedings of the 2014 conference on empirical methods in natural language processing (EMNLP), 2014, pp. 1532–1543.
- Babenko, A.; Lempitsky, V. Efficient indexing of billion-scale datasets of deep descriptors. In Proceedings of the Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, 2016, pp. 2055–2063.
- Kraska, T.; Beutel, A.; Chi, E.H.; Dean, J.; Polyzotis, N. The case for learned index structures. In Proceedings of the Proceedings of the 2018 international conference on management of data, 2018, pp. 489–504.
| Algorithm | 10K vectors | 100K vectors | 500K vectors | 1M vectors |
|---|---|---|---|---|
| Linear Search | 0.12 | 1.23 | 6.18 | 12.45 |
| LSH (10 tables) | 0.08 | 0.15 | 0.31 | 0.58 |
| IVF (100 clusters) | 0.09 | 0.18 | 0.35 | 0.67 |
| Hybrid Approach | 0.07 | 0.13 | 0.28 | 0.52 |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
