datasette.io VS litestream

Opened an issue exploring alternatives here: https://github.com/simonw/datasette.io/issues/109

I decided to just drop "any size" but keep "any shape".

Here's an example from one of my projects: https://github.com/simonw/datasette.io/blob/main/.github/workflows/deploy.yml

I've come around to almost the opposite approach.

I pull all of the data I can get my hands on (from Twitter, GitHub, Swarm, Apple Health, Pocket, Apple Photos and more) into SQLite database tables that match the schema of the system that they are imported from.

For my own personal Dogsheep (https://simonwillison.net/2020/Nov/14/personal-data-warehous...) that's 119 tables right now.

Then I use SQL queries against those tables to extract and combine data in ways that are useful to me.

If the schema of the systems I am importing from changes, I can update my queries to compensate for the change.

This protects me from having to solve for a standard schema up front - I take whatever those systems give me. But it lets me combine and search across all of the data from disparate systems essentially at runtime.

I even have a search engine for this, which is populated by SQL queries against the different source tables. You can see an example of how that works at https://github.com/simonw/datasette.io/blob/main/templates/d... - which powers the search interface at https://datasette.io/-/beta

I've been exploring this technique more over the past year and I really like it - https://datasette.io (code at https://github.com/simonw/datasette.io ) is a more recent and much more complicated example.

Extracting links from markdown and using them to populate some additional columns or tables at build time would be pretty straight forward.

I run SQLite in serverless environments (Cloud Run, Vercel, Heroku) for dozens of projects... but the trick is that they all treat the database as a read-only asset.

If I want to deploy updated data, I build a brand new image and deploy the application bundled with the data. I tend to run the deploys for these (including the database build) in GitHub Actions workflows.

This works really well, but only for applications that don't need to apply constant updates more than a few times an hour! If you have a constant stream of updates I still think you're better off using a hosted database like Heroku PostgreSQL or Google Cloud SQL.

One example of a site I deploy like that is https://datasette.io/ - it's built and deployed by this GitHub Actions workflow here: https://github.com/simonw/datasette.io/blob/main/.github/wor...

I have not, but I keep meaning to collate everything I've learned into a set of useful defaults just to remind myself what settings I should be enabling and why.

Regarding Litestream, I learned pretty much all I know from their documentation: https://litestream.io/

This presentation is focused on the use-case of vertically scaling a single server and driving everything through that app server, which is running SQLite embedded within your application process.

This is the sweet-spot for SQLite applications, but there have been explorations and advances to running SQLite across a network of app servers. LiteFS (https://fly.io/docs/litefs/), the sibling to Litestream for backups (https://litestream.io), is aimed at precisely this use-case. Similarly, Turso (https://turso.tech) is a new-ish managed database company for running SQLite in a more traditional client-server distribution.

This post intends to help you setup replication for SQLite using Litestream.

I've been messing around with litestream. It is so cool. And, I either found a bug in the -timestamp switch or don't understand it correctly.

What I want to do is time travel into my sqlite database. I'm trying to do some forensics on why my web service returned the wrong data during a production event. Unfortunately, after the event, someone deleted records from the database and I'm unsure what the data looked like and am having trouble recreating the production issue.

Litestream has this great switch: -timestamp. If you use it (AFAICT) you can time travel into your database and go back to the database state at that moment. However, it does not seem to work as I expect it to:

https://github.com/benbjohnson/litestream/issues/564

I have the entirety of the sqlite database from the production event as well. Is there a way I could cycle through the WAL files and restore the database to the point in time before the records I need were deleted?

Will someone take sqlite and compile it into the browser using WASM so I can drag a sqlite database and WAL files into it and then using a timeline slider see all the states of the database over time? :)

We're using SQLite in production very heavily with millions of databases and fairly high operations throughput.

But we did run into some scariness around trying to use Litestream that put me off it for the time being. Litestream is really cool but it is also very much a cool hack and the risk of database corruption issues feels very real.

The scariness I ran into was related to this issue https://github.com/benbjohnson/litestream/issues/510

Litestream is a library that allows you to easily create backups. You can probably just do analytic queries on the backup data and reduce load on your server.

https://litestream.io/

One possible strategy is to have one directory/file per customer which is one SQLite file. But then as the user logs in, you have to look up first what database they should be connected to.

OR somehow derive it from the user ID/username. Keeping all the customer databases in a single directory/disk and then constantly "lite streaming" to S3.

Because each user is isolated, they'll be writing to their own database. But migrations would be a pain. They will have to be rolled out to each database separately.

One upside is, you can give users the ability to take their data with them, any time. It is just a single file.

[0]. https://litestream.io/

Upstream Kuma uses a local SQLite database to store account data, configuration for services to monitor, notification settings, and more. To make sure that our data is available across redeploys, we will bundle Uptime Kuma with Litestream, a project that implements streaming replication for SQLite databases to a remote object storage provider. Effectively, this allows us to treat the local SQLite database as if it were securely stored in a remote database.