Since version 1.8, Spring data project includes an interesting feature - through a simple API call developer can request database query results to be returned as Java 8 stream. This technique can be particularly useful when processing large datasets (for example, exporting larger amounts of database data in a specific format).

when using MySQL in order to really stream the results we need to satisfy three conditions:

• Forward-only resultset
• Read-only statement
• Fetch-size set to Integer.MIN_VALUE

• We've seen significant performance improvements when using streaming (via scrollable resultsets) vs paging, admittedly in a very specific task of exporting data.

• Spring Data's new features give really convenient access to scrollable resultsets via streams.

• There are gotchas to get it working with MySQL, but they are manageable. There are further restrictions when reading scrollable result sets in MySQL - no statement may be issued through the same database connection until the resultset is fully read.

• The export works fine because we are writing results directly to HttpServletResponse. If we were using default Spring's message converters (e.g. returning stream from the controller method ) then there's a good chance this would not work as expected.