do_not_flush_freed_temp_pages.patch is a work-in-progress (non-working) patch that would implement part of this: when a page in the temporary tablespace is freed, it will be removed from the flush list.

Perhaps we should use asynchronous writes for advancing the redo log checkpoint, and synchronous I/O for anything else (page reads and writes).

For example, if a user thread wants to replace a buffer pool page with something else (to initialize or read a different page), then it could write a page to the temporary tablespace, unless the page was already marked to be free. This would be the only source of writes to the temporary tablespace file.

Read-ahead requests could be delegated to a background thread.

MDEV-15528 tracks freed pages and handles them in 3 ways:

• Skip writing any page payload for freed pages. (This fixes MDEV-12226.)
• For page_compressed tables, punch holes.
• Else, if background scrubbing is enabled, overwrite freed pages with zeroes.

MDEV-8139 will further improve the scrubbing and may implement trimming of freed pages from the end of data files.