ClickHouse’s vertical merge splits a merge into two stages: merge the key and record where each output row came from (one byte per row), then gather each payload column…
ClickHouse’s hash table has no occupancy bit, no tombstone, and no sentinel pointer.
ClickHouse caches query results by hashing the parsed query, not the text you typed, plus the settings and database that could change the answer.
ClickHouse compiles hot scalar expressions to native code with LLVM.
tmux’s parser has no clever trick in it. It’s a state machine with a transition cache, a bsearch(), a trie, and a width cache — four small optimisations, each of which swaps an…