acid-state in production?

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Nolan Darilek

Aug 11, 2014, 11:59:49 PM8/11/14

Fairly new to Haskell and examining it for an app I'm building. I like
the idea of building the data store directly into my app, and working
with native data rather than passing through an intermediate ORM.

Out of curiosity, how practical is acid-state for production use? Is it
mainly meant for fast prototyping, then replacing with a database at any
kind of serious volume? Or can I take an app from my laptop to the
server without, say, the usual replacement of SQLite with Postgres?

I understand "production" is a vague term. Assume a
low-to-medium-traffic app. Obviously, once you get beyond that, there is
no clear-cut answer.

Also, if anyone runs acid-state in production, would you mind sharing
experiences? I'm a bit worried about using a library vs. a dedicated
database for persistence, though perhaps it's performant enough that if
I ever reached volumes it can't handle, I'm having a good problem and
can likely pay someone to export data to some more mainstream database. :)

Jeremy Shaw

Aug 12, 2014, 12:04:25 AM8/12/14
to HAppS
acid-state should be great for high volume. The bigger issue is the
size of your dataset -- as it all needs to fit into RAM.

I use acid-state exclusively and I think it is great. A more
impressive endorsement though is hackage -- which uses acid-state.

- jeremy
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Adam Bergmark

Aug 12, 2014, 7:58:28 AM8/12/14
I talked to some people using acid-state in production at ZuriHac. They said it worked very well.

We tried using it but struggled because it was hard to inspect data ad-hoc. They told me they built proper tools for this from the get go and didn't see it as a problem.

- Adam

Blake Rain

Aug 12, 2014, 10:37:54 AM8/12/14
We have been using acid-state for quite a long time now. Never any issues.

As Jeremy Shaw mentioned, the issue is the data size: our largest project uses around 4.5G. I have no idea how large Hackage is...

One issue that can raise it's head is the time it takes to load the state from a large number of events. I would recommend judicious use of checkpoints :)
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