Q: Is there a way to stream query results asynchronously?

A: Streaming API is supported.

Streaming processing can be done using the stream method. This returns an Fs2 Stream.

val stream: fs2.Stream[DBIO, String] = sql"SELECT * FROM `table`".query[String].stream

In MySQL, the behavior of streaming changes significantly depending on the UseCursorFetch setting:

• UseCursorFetch=true: True streaming processing using server-side cursors
• UseCursorFetch=false: Limited streaming processing (with memory constraints)

For handling large datasets, we recommend setting UseCursorFetch=true.

Reference

• Selecting Data - Efficient Processing of Large Data with Streaming