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Comment by darthShadow | Hacker News Reader

These may be useful reading:

https://github.com/TryGhost/node-sqlite3/issues/408#issue-57...

https://github.com/WiseLibs/better-sqlite3/issues/32#issueco...

Copying a quote from the second:

> The sqlite3 C API serializes all operations (even reads) within a single process. You can parallelize reads to the database but only by having multiple processes, in which case one process being blocked doesn't affect the other processes anyways. In other words, because sqlite3 serializes everything, doing things asynchronously won't speed up database access within a process. It would only free up time for your app to do other things (like HTTP requests to other servers). Unfortunately, the overhead imposed on sqlite3 to serialize asynchronous operations is quite high, making it disadvantageous 95% of the time.

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The sqlite3 C API very much does not serialize "all operations within a single process."

The way threading and concurrency work in SQLite may not mesh well with NodeJS's concurrency model. I dunno, I'm not an NodeJS/libuv expert.

But at the C API level that statement is just wrong. Normally you cannot share a single connection across threads. If you compile SQLite to allow this, yes, it'll serialize operations using locks. The solution is to create additional database connections, not (necessarily) launch another process. With multiple database connections, you can have concurrency, with or without threads.

https://sqlite.org/threadsafe.html

Again, whether this is viable in NodeJS, I have no idea. But it's a Node issue, not a C API issue.

BTW, we're commenting on a Ruby article, and SQLite in Ruby has seen "recent" advances that increase concurrency through implementing SQLite's BUSY handler in Ruby, which allows the GVL lock to be released, and other Ruby and SQLite code to run while waiting on a BUSY connection.

https://fractaledmind.github.io/2023/12/11/sqlite-on-rails-i...

The user-supplied busy handler has been available for a long while, it's just that the Rails connection adapters did not quite use it right. Indeed, there is elevated interest in SQLite these days.

This explanation is extremely misleading. For many of my projects, vast majority of the operations do not use the database . And the few that does, contains long running huge joins/aggregates. Using the sync API is just straight up terrible because the task will block literally everything else that does not use the db in js, meaning generating a report in the background can literally prevent you from handling any requests. (I did end up using better sqlite 3 because they are personal projects and getting stuck for 2 seconds when the scheduled report generation happens is ok ish for the a few people using it. But I will not consider using better sqlite 3 for any future projects)

I suppose you want to run the longer, expensive queries in the background, EG a worker, or a separate process. Shouldn't be _that_ hard to setup.

Maybe you can even create your own async wrapper that delegates any query to a separate process.

Tnx for the links!

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