hcache on tmpfs?

[Cameron Simpson]

On 30Mar2023 12:49, void <void at f-m.fm> wrote:
>Mutt's config for $tmpdir points to a tmpfs here which is memory-backed
>and therefore v quick. The perms for this are set to 700.
>
>I was wondering which hcache would be best in this use context. I'd like
>to point the hcache to this tmpdir. But I understand that kyotocabinet
>is memory-based already, so am unsure which to choose.

"memory based" might just mean memory mapped - kytotocabinet still has 
persistent storage. Using a tmpfs will mean (a) it uses your physical 
RAM (or possibly swap?) even when you're not using mutt and (b) the db 
will vanosh on reboot.

I've used kyotocabinet elsewhere but do not know much, if anything, 
about its internals.

Are you asking about picking a db backend (eg kyoto versus dbm)?

Subjectively, I'd have thought for moderate data they'd be similar on a 
tmpfs. If you're prepared to rebuild the whole hcache after a reboot 
(which of course might be very infrequent for you) it still may not 
matter.

I think this post successfully provides little insight :-(

Can you qualify what your concerns are here?

I use an hcache. On persistent storage, which is an SSD for me. My 
"python" folder has 157000 messages in it and opening mutt on it and 
then closing it just took about 20 seconds including eyeballing the top 
line to read the message count. This mutt was built with tokyocabinet, 
which I expect is used for the hache (nothing else would have any use 
for it).

Cheers,
Cameron Simpson <cs at cskk.id.au>