Anecdotal evidence, but I produced a medium-size crawl in the past (~20TB compressed). I used distributed resources with off-the-shelf libraries (i.e. warcprox etc.) and managed to get corrupted data in some cases where neither the length-delimited (i.e. offset + payload length) nor the newline-delimited (triple newlines between records) logics were valid any longer. Took me some time to build a repair tool for that.

Sqlite has an amazing set of well-understood and documented guarantees on top of performance, there's a host of potential validation tools to choose from and you can even use transactions etc. So that alone seems like a great idea.

What's more, you can potentially skip CDX files if you have sqlite databases (or build your own meta sqlite database for the others quickly).

A bit late to this thread, but I think WARC is a reasonable format for raw HTTP traffic. We should definitely have better tools to ensure WARC files produced are valid, and that's one of the things we build at Webrecorder.

Unless you're crawling really text heavy content, most of the WARC data is binary content that doesn't really need to be in a db. However, sqlite or database as replacement for CDX is an appealing option, where WARC files can remain static data at rest and derived data (offests, full-text search, can be put into a db.

We are experimenting with a new format, WACZ, which bundles WARC files into a ZIP, while adding CDXJ and exploring sqlite as an option for full-text search. I agree that it's better to build on solid, existing formats that can be validated, especially when large amounts of data are concerned!

Is there a forum or somewhere web crawlers hang out online? I'd love the learn about more sophisticated projects like this.

In github issues of said projects, and at scientific web archival conferences.

Although I'd absolutely welcome some sort of channel!

Topics include Issues and activities across projects. These topics are quite active, e.g.

https://github.com/topics/crawling https://github.com/topics/web-scraping https://github.com/topics/web-archiving

> What is the advantage of moving around .sqlite-files, over just loading the (compressed) WARCs into sqlite databases when you need them?

I suppose there could be made a case for easy extension: You don't need to change the entire spec to add another table in the SQLite database, maybe containing other metadata.

> WARC's real selling pint is that it's such an extremely portable format.

I mean, so is SQLite: it is also apporoved as a LoC archival method. (See SQL Archive [0])

[0]: https://www.sqlite.org/sqlar.html

> What is the advantage of moving around .sqlite-files, over just loading the (compressed) WARCs into sqlite databases when you need them?

The .warc spec is ideal. I'm not saying we replace it (ref. xkcd: standards).

On top of what uniqueid said, "loading" is much slower and more cumbersome than it sounds. I'm not saying SQLite will replace text (maybe my aphorism sounded too firm). I'm saying that maybe along with the .warc.gz archives at rest, one could have .sql.gz files at rest as well.

In other words: why not move ACID-compliant archives moving around?

Seems like the benefit of sqlite is the sort of usecases where you maybe don't want to load everything you've crawled into a search engine, but want to be able to cherrypick the data and retrieve specific documents for further processing. Which is certainly a use case that exists, and indeed not really what WARC is designed for.

Great for most end user facing applications though.

End-user facing applications usually don't consume website crawls, do they? That's impractical for many reasons, the sheer size alone being perhaps the biggest obstacle.

If you want to do something like have an offline copy of a website, ZIM[1] is a far more suitable format as it's extremely space-efficient and also fast.

[1] https://docs.fileformat.com/compression/zim/