Hacker News Reader

Comment by tarr11 | Hacker News Reader

Some databases also have the ability to be instantly portable, like a sqlite file.

You can tar up your flat files as well, but that is a separate process and can be time consuming for larger directories.

Perhaps there is a use case for a file system backed by portable database like sqlite, such that you can just mount the volume and send it around without pain, but can prefer to use normal command line utils (ls, rm, grep, etc) instead of interacting via SQL.

View on HN

I’ve had this research paper on my reading list for a while (but haven’t gotten to reading the full thing)[1]. Not necessarily just a file system but It lays out an entire operating system backed by a database and OS state interactions are done through SQL.

1. https://vldb.org/pvldb/vol15/p21-skiadopoulos.pdf

If you're running Postgres in Docker, you can just stop the container and tar up the data volume and start it somewhere else

(This also works without Docker of course, but Docker makes me feel safer when I do stuff like this)

This procedure is officially documented (1).

Since we're talking about copying a folder, I'm not sure why you'd feel safer doing it via an additional layer of abstraction.

(1) https://www.postgresql.org/docs/14/backup-file.html

Why does Docker makes you feel safer here? Is it because you feel more confident there is no database process still running?

If you're an ignorant fool such as myself, your knowledge of a database's internals is sufficient only to inspire fear. With Docker I know that whatever black magic the database uses is contained within a black box I can copy wholesale. Anything important must be in there, since I didn't give it anything else!

It's more about, I don't like having a global directory namespace that everything gets dumped into.

I know that PG data is usually in /var/lib/postgresql/data, but I like Docker because if I ever need a 2nd or 3rd database on one system, I can give them more meaningful names and not feel like I'm touching Important System-Wide Stuff.

Does this work even when the Postgres is updated to a newer version? This would make me want to use docker as well.

I'd have to read the Postgres docs to be sure. Postgres has really good docs.

My intuition is that you're expected to do some kind of migration or export/import, because the on-disk format probably changes between major versions.

> You can tar up your flat files as well, but that is a separate process and can be time consuming for larger directories.

We have file formats like ODF which are just zip packages with regular files inside

I believe hdf5 is the format that can serve that purpose.

Reply on news.ycombinator.com