Handling `infileStreamFactory` at connection-level

[loozhengyuan]

The infileStreamFactory option only works when calling connection.query() or connection.execute(), which is as documented.

However, if I set it on a connection-level as suggested in #1080, the configuration is currently not propagated when calling connection.query() or connection.execute(). Since I am using Sequelize, which only exposes the connection configuration via dialectOptions, there is no other way I can set the infileStreamFactory option.

To help move this forward, I am keen to know where the change should be made:

1. To support the infileStreamFactory connection option in mysql2 and pass it when calling Commands.Execute()/Commands.Query(); or
2. To make the change in Sequelize instead to expose these options at a query-level.

Any comments/feedback is deeply appreciated, thanks!

[sidorares]

hi @loozhengyuan I'm keen to have this fixed on mysql2 side, can we start with a simple repro example?
We might to change api slightly, if infileStreamFactory is set on a connection/pool level it probably needs to see the query text to be able to decide which file to return, maybe pass sql as a second parameter: (path, fullQuery) => ReadableStream

[loozhengyuan]

Sure, I have created a repro of the issue, using mysql2 and sequelize to depict my current situation. Feel free to try it out.

Separately, I also created a draft version of the patch and managed to get it working in the feat/connection-level-infilestreamfactory branch. Not too familiar with the code base so happy to hear any feedback that you have. I can also submit the PR for review if the changes are in the right direction.

[sidorares]

the change looks ok. We might actually not need extra sql parameter. My thinking was more of a "virtual file system": given query X and a file name Y (from that query), return a way to read the data. But in reality most use cases is just a security gate / allowlist: an INFILE query wants a file XYZ, if it's a safe path read the file under the same name from fs

Feel free to open a PR. It's probably a minor version bump ( not patch ): clients using updated mysql2 library might not work with the version before your fix.