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Tag: hash

Implementing a Key-Value Store – Part 5: Hash table implementations

This is Part 5 of the IKVS series, “Implementing a Key-Value Store”. You can also check the Table of Contents for other parts.

In this article, I will study the actual implementations of hash tables in C++ to understand where are the bottlenecks. Hash functions are CPU-intensive and should be optimized for that. However, most of the inner mechanisms of hash tables are just about efficient memory and I/O access, which will be the main focus of this article. I will study three different hash table implementations in C++, both in-memory and on-disk, and take a look at how the data are organized and accessed. This article will cover:

1. Hash tables
    1.1 Quick introduction to hash tables
    1.2 Hash functions
2. Implementations
    2.1 unordered_map from TR1
    2.2 dense_hash_map from SparseHash
    2.3 HashDB from Kyoto Cabinet
3. Conclusion
4. References