> On Mar 6, 2023, at 16:24, Siddharth Jain <siddhsql@xxxxxxxxx> wrote: > My question: How can it then store a B Tree on disk? I would think storing a B Tree requires storing disk offset addresses and so on (for a node to navigate to another etc.). For this, one would need to write directly to the disk using low-level disk access functions and not use file system API. All of PostgreSQL's relations (tables and indexes) are stored in files. (They're actually stored in a set of files if it's larger than 1GB, but each relation is treated as one logical file.) The "pointers" in this case are just offsets from the start of that file. There's some additional information here: https://www.postgresql.org/docs/current/storage.html and here: https://www.postgresql.org/docs/current/btree-implementation.html
