Data Engineering & Databases .

Storage engine internals: a write-ahead log, double-buffered checkpoints and checksums, crashed at every file-system call to prove recovery.

A multithreaded block storage engine in C++17 for Linux: block reads and writes, atomic batches, snapshots and CRC-32C checksums, with crash recovery from a write-ahead log and double-buffered checkpoints. Validated by 35 fault-injection scenarios that crash it at every file-system call, flip every byte of its metadata, and kill it mid-write with SIGKILL.

SQL views and five SQL classifiers over 100,000 drives and their telemetry, ingested with COPY in 26 seconds.

A validation platform for autonomous-driving software builds. It replays the same seeded scenarios through a known-good build and a release candidate, compares what the two did, classifies every regression, and turns each cluster of failures into a report an engineer can reproduce with one command. One 100,000-drive campaign runs end to end in 52 seconds.

A million messy records joined with C++ MapReduce on Hadoop, then queried in Hive.

A million messy music records that shared no common keys. I joined them with C++ MapReduce on a Hadoop cluster, then asked the clean data what actually makes a song popular.

50 thousand relationships in Neo4j for two-hop queries, with profiles and content in MongoDB alongside.

A social platform that thinks in relationships. It keeps 50 thousand connections in a graph database and answers who knows who in two hops, with profiles and content living in their own store alongside.