August 21st, 2024

Immutable Data Structures in Qdrant

Qdrant's article highlights the benefits of immutable data structures in vector databases, improving performance and memory efficiency, while addressing challenges through mutable segments and techniques like perfect hashing and defragmentation.

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Immutable Data Structures in Qdrant

Qdrant's article discusses the advantages of using immutable data structures in vector databases, particularly in enhancing performance and optimizing memory usage. Traditional data structures, while effective for specific operations, often struggle with performance in real-world applications due to hardware limitations. Immutable structures can improve efficiency by allowing for better memory allocation and reducing cache misses. The article highlights the use of perfect hashing to eliminate collisions in hash tables, which is crucial for fast data retrieval, especially from disk storage. Additionally, it introduces the concept of defragmentation, which groups relevant data together to minimize read overhead, significantly boosting performance in multi-tenant systems. Despite the benefits, immutable structures present challenges, such as higher costs for updates and potential rebuilding overhead. Qdrant addresses these issues by allowing mutable segments for new data and optimizing the transition to immutability. Overall, the combination of these techniques positions Qdrant to leverage hardware optimizations effectively, making it suitable for read-heavy workloads typical in search engines.

- Immutable data structures enhance performance and memory efficiency in vector databases.

- Perfect hashing minimizes collisions, improving data retrieval speed.

- Defragmentation reduces read overhead by grouping relevant data.

- Qdrant allows mutable segments to manage updates efficiently.

- The architecture balances the benefits of immutability with the need for flexibility in data management.

Link Icon 2 comments
By @ThinkBeat - 4 months
I do not understand how you can pack 1536d into 192 bytes ??? That some entirely impossible?

> Vector search, on the other hand, requires reading a lot of small vectors, which might create a large overhead. It is especially noticeable if we use binary quantization, where the size of even large OpenAI 1536d vectors is compressed down to 192 bytes. Dataset size: 2M 768d vectors (~6Gb Raw data), binary quantization, 650Mb of RAM limit. All benchmarks are made with minimal RAM allocation to demonstrate disk cache efficiency.

By @wredue - 4 months
>Immutable data structures, while tricky to implement correctly, offer significant performance gains, especially for read-heavy systems like search engines. They allow us to take full advantage of hardware optimizations, reduce memory overhead, and improve cache performance.

Nonsense.