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missing docs: web worker #595
Description
The README says
If you don't want to run CPU-intensive SQL queries in your main application thread, you can use the more limited WebWorker API.
It gives a couple examples and caveats, but I need a lot more information to use the feature. I need a list of messages I can pass, what the worker will pass back, and a description of what the limitations are. There's no page on the website or GitHub wiki about this.
Other issues:
- The docs say to get the file from the releases page, but I'd rather get them from
node_modules/sql.js/distso they get version updates. But someone in this issue said that won't work. This is something that should be covered in a full explanation of how to use web workers. @types/sql.jsis missing types for the web worker API.- Existing issue caused by these missing docs: Is it possible to use transaction with web worker? #490
Because of these missing docs, for my app I'm going to write my own custom web worker using the normal SQL.js API.
I'll also highlight the proposal to remove the whole web worker API, which would be a way to avoid this whole issue (though you'd still want the docs to have some hints about how/why to write a custom web worker): #377
Activity
lovasoa commentedon Oct 13, 2024
Hi ! That would be very useful indeed ! Do you want to write this documentation ?
The underlying worker code is quite simple; it's here: https://github.com/sql-js/sql.js/blob/master/src/worker.js
scola84 commentedon Oct 18, 2024
Would it be possible to add
getRowsModifiedto the worker?lovasoa commentedon Oct 19, 2024
Yes! The code is here: https://github.com/sql-js/sql.js/blob/master/src/worker.js you can open a pull request. Don't forget to add a test for it !
scola84 commentedon Oct 19, 2024
Alright, I'll look into it next week.
If you look at for example https://github.com/brianc/node-postgres/blob/master/packages/pg/lib/result.js#L13, you can see that the
rowCountis part of every query result. That would mean I could also implement something like:Do you think that is a good idea? (Maybe
rowsModifiedshould be inresults?)Or would you prefer just a
getRowsModifiedaction?lovasoa commentedon Oct 19, 2024
I think a separate action, preventing an new wasm call after each request, is better.
Just out of curiosity, do you have very strict performance requirements, or something else that prevents you from just using SQLite's built-in
changessql function?https://www.sqlite.org/lang_corefunc.html#changes
scola84 commentedon Oct 28, 2024
I've created a PR.
I was not aware of the changes function since I have only very little experience with SQLite. I like your Worker API and with the addition of the getRowsModified function I have everything I need.
By the way, I noticed that when I execute a query with an empty result set, no headers are returned. In libraries for other SQL dialects this usually is the case. Is it specific to SQLite or to your library that no headers are returned in the case of an empty result set?
lovasoa commentedon Oct 28, 2024
You can use Statement.getColumnNames to read the column names. But it's not in the web worker api.
scola84 commentedon Oct 28, 2024
OK, thanks. Now I understand the remark "you can use the more limited WebWorker API" on the website. Maybe I'll switch to the
initSqlJsapproach later, for now the Worker will do.