Optimizing Optimistic Concurrency Control for Tree-Structured, Log-Structured Databases: The core of the system is a log roll-forward algorithm, called meld, that does optimistic concurrency control. Meld is inherently sequential and is therefore the main bottleneck. Our main algorithmic contributions are optimizations to meld that significantly increase transaction throughput. They use a pipelined design that parallelizes meld onto multiple threads. The slowest pipeline stage is much faster than the original meld algorithm, yielding a 3x improvement of system throughput over the original meld algorithm.