restoration after crash slowness, any way to improve?

-hackers,

So this is more of a spit balling thread than anything. As I understand
it, if we have a long running transaction or a large number of wal logs
and we crash, we then have to restore those logs on restart to the last
known good transaction. No problem.

I recently ran a very long transaction. I was building up a large number
of rows into a two column table to test index performance. I ended up
having to kill the connection and thus the transaction after I realized
I had an extra zero in my generate_series(). (Side note: Amazing the
difference a single zero can make ;)). When coming back up, I watched
the machine and I was averaging anywhere from 60MBs to 97MBs on writes.
That in itself isn't that bad over a single thread and a single SSD,
doing what it is doing.

However, since I know this machine can get well over 400MBs when using
multiple connections I can't help but wonder if there is anything we can
do to make restoration more efficient without sacrificing the purpose of
what it is doing?

Can we have multiple readers pull transaction logs into shared_buffers
(on recovery only), sort the good transactions and then push them back
to the walwriter or bgwriter to the pages?

Anyway, like I said, spitballing and I thought I would start the thread.

Sincerely,

JD

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