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@stuarthalloway If I start using Ions with Solo, will it automatically upgrade to Production if the app demands for it? Or, will I have to do it manually? Your talk on Ions seem to suggest that it will happen automatically, I don't have to worry about the scaling. Please advise.


Another query I have: The Datomic Cloud pricing seems to be time-based (usage or no usage) rather than usage-based. Is my understanding correct?


My understanding of usage is Transactions/Queries


@amarjeet pricing is by EC2/hour on instances that run in your account


@stuarthalloway and the software/hr is for datomic - even if there aren't any transaction/queries - because it's just live waiting for transactions/queries? The reason I am asking is because I had tried Aws lambda and dynamodb combination - I wanted to compare the cost impact .


yes, although note that Datomic can do more than transactions / queries, e.g. serve web requests


True, I have better reasons to use Datomic of course :) I was just trying to estimate my pocket burdens.


Thanks, appreciate it.

Alex Miller (Clojure team)17:06:00

we ran the Strange Loop CFP app (which is a Datomic cloud app) for about a month, which is relatively low traffic - just people submitting talks and reviewing talks and the Datomic portion of the cost was about $11/month (EC2 may have been like $100 or something, don’t remember)

Alex Miller (Clojure team)17:06:29

it’s a little hard to separate out from other stuff in same account, but maybe that arbitrary real data point is useful

Alex Miller (Clojure team)17:06:40

this was not ions, just d cloud

Alex Miller (Clojure team)17:06:48

(although I intend to move it to ions :)

Alex Miller (Clojure team)17:06:25

I expect ions would allow me to drop this cost considerably as the app would run in the instances I have for d cloud rather than on an additional box

Alex Miller (Clojure team)17:06:11

and I used to run on-prem on a box on aws, that at least twice as expensive


Hmm, this is helpful, thanks :)

Alex Miller (Clojure team)17:06:04

nothing beats just trying it of course

Alex Miller (Clojure team)17:06:10

you can get daily spend numbers in aws


Yes, have decided to test this for a few days


(datomic ions) sometimes the lambda called by api gateway fails with:

  "errorMessage": "Timeout connecting to cluster node.",
  "errorType": "datomic.ion.lambda.handler.exceptions.Unavailable",
  "stackTrace": [


can you say more about the situation(s) when this occurs? Are you (re)deploying code?


anybody knows what the problem is? :thinking_face: