On 05/02/2020 21:56, Jeff Davis wrote:
On Tue, 2020-02-04 at 18:10 +0200, Heikki Linnakangas wrote:
I'd love to change the LogicalTape API so that you could allocate
and
free tapes more freely. I wrote a patch to do that, as part of
replacing
tuplesort.c's polyphase algorithm with a simpler one (see [1]), but
I
never got around to committing it. Maybe the time is ripe to do that
now?
It's interesting that you wrote a patch to pause the tapes a while ago.
Did it just fall through the cracks or was there a problem with it?
Is pause/resume functionality required, or is it good enough that
rewinding a tape frees the buffer, to be lazily allocated later?
It wasn't strictly required for what I was hacking on then. IIRC it
would have saved some memory during sorting, but Peter G felt that it
wasn't worth the trouble, because he made some other changes around the
same time, which made it less important
(https://www.postgresql.org/message-id/CAM3SWZS0nwOPoJQHvxugA9kKPzky2QC2348TTWdSStZOkke5tg%40mail.gmail.com).
I dropped the ball on both patches then, but I still think they would be
worthwhile.
- Heikki
