# Tech Computer science, databases first: storage, transactions and recovery, then operating systems, networks, languages and algorithms. > Canonical URL: https://sudohulk.com/tech > Feed: https://sudohulk.com/tech/rss.xml > 4 entries, newest first. Append .md to any path for its markdown. > Author: Vignesh Kumar A --- - [How PostgreSQL tells every connection its cache is stale](https://sudohulk.com/writing/postgres-cache-invalidation.md): Each PostgreSQL connection caches the catalog for itself. How a change is announced to all of them at commit through a shared ring, and what happens to a connection that falls behind. (essay, 2026-10-17) - [Full-page writes and torn pages](https://sudohulk.com/writing/full-page-writes-and-torn-pages.md): Why the first change to a page after a checkpoint carries the whole 8 KB page in WAL. (note, 2026-09-22) - [Lazy transaction id assignment](https://sudohulk.com/writing/lazy-xid-assignment.md): A transaction does not get an xid at BEGIN; it gets one the first time it writes. (note, 2026-09-22) - [pd_lsn vs record LSN](https://sudohulk.com/writing/pd-lsn-vs-record-lsn.md): Two LSNs that are easy to mix up, and the rule recovery uses to compare them. (note, 2026-09-21)