How ClickHouse's Sparse Column Stores Only the Rows That Differ
A sparse column stores only the rows that differ from the default, plus a sorted offsets array.
Performance
tmux Parses Escape Sequences Fast: Four Boring Optimisations That Matter
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…
PostgreSQL Speeds Up Hash Joins: Specialising the Expression Interpreter
PostgreSQL pattern-matches a hash join’s compiled expression steps and swaps the general-purpose interpreter for a specialised C function, which is worth up to 20% on probe-heavy …
PostgreSQL Waits for Locks: The Spin, Sleep, and Kernel Ladder
PostgreSQL’s wait ladder spins in user space, then backs off with a jittered exponential delay so spinners don’t convoy, and only then blocks in the kernel — and it learns how long …
PostgreSQL Locks Buffers Without LWLocks: One 64-Bit Word
PostgreSQL 20 moved buffer content locks out of the LWLock machinery and into the buffer’s own 64-bit state word, so taking one costs a single compare-and-swap.