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I have a question about cold-starts in Ions. I’m running the sample Ions on solo and the cold start is 15-20secs after a deploy. I’m wondering if this is the lambda or the cloud node or both? I could see that (in future) the lambdas could be moved to cljs but not the cloud nodes so this knowledge will affect some architecture decisions i.e. designing in tolerance for cloud node cold-starts

Oliver George06:06:54

I think I saw a reference which indicated that "integration with ElasticCloud" was a possible future addition to Datomic Cloud but I can't find it for the life of me. Am I making that up? My guess is that it would facilitate more diverse search indexing (already used for full-text search).


We are considering this, and it is also pretty easy to roll it yourself.


@steveb8n that is probably the Lambda. Cloud nodes will never be cold once you move to production topology.

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Hi, I'm trying to understand t a little better. Suppose you do a transaction: db-before, db-after and the transaction itself all have values for t. How do these values relate to eachother?


hi @jlmr Time moves forwards: db-after's t = tx t > db-before's t


and good to know that tx t is always the same to db-after t


Root exception is this:

Error building classpath. Failed to read artifact descriptor for com.datomic:ion:jar:0.9.7
org.eclipse.aether.resolution.ArtifactDescriptorException: Failed to read artifact descriptor for com.datomic:ion:jar:0.9.7


and running clj will also give me the same exception


ok, found the issue with the Ions Tutorial. For AWS beginners, it would be great to enhance this bit:

This tutorial presumes AWS Administrator permissions
since coming out of the Setting Up/User Access/Getting Started you will not have a user with that policy added. May I suggest adding:
Make sure the user you set up in User Access also receives the AdministratorAccess policy so the mvn dependencies can be downloaded. 
And link to


It's easy to get this confused since earlier in the User Access tutorial for Datomic Cloud I had added an Administrator Policy.