one can (and should) split stacks in a solo cloud install, correct? And recreate the storage stack and solo compute stack?

Hi. I use datomic on-prem (via the Peer API) with a number of Datomic installations (think production, staging etc) In most of them everything is OK, but for one of them, query latency is consistently high; 1500ms, for the simplest, cheapest possible query. Indices are in place. We also tried to rule out basic stuff (configuration/environment differences, etc) What are some possible causes, or things we can do to troubleshoot this?

@vemv what is different about the one that is high latency?

I noticed in on-prem there is an optional :db/index attribute (https://docs.datomic.com/on-prem/schema.html#operational-schema-attributes) but I don't see one in the cloud docs. Are all attributes indexed in cloud?

I don't see it exlicitly stated in the docs, just alluded to here: "Datomic datalog queries automatically use multiple indexes to support a variety of access patterns" (https://docs.datomic.com/cloud/whatis/data-model.html) The differences page, doesn't mention it other than the full-text difference: https://docs.datomic.com/on-prem/moving-to-cloud.html#text-search

all attributes are indexed in cloud

Are lookup refs not valid values for transactions for ref attributes in cloud? As per https://blog.datomic.com/2014/02/datomic-lookup-refs.html Similarly, they can be used in transactions to build ref relationships. but I get “entity not resolved” with the full tuple as an error in cloud

what did you try and what did it error?

@eagonmeng what version of cloud?

note: https://docs.datomic.com/cloud/releases.html#569-8835 • (Fix: resolve tempids for reference attributes inside tuples.)

however, you should move to the latest; it includes a fix for a different regression in that version

I need to write to several different "schemas" in a single Datomic transaction, e.g., phone numbers, emails accounts, person information and address information. All of these write create eids which are then stored in a customer. I need to do this atomically, but I cannot figure out how to recover eids from within a transaction function. Any ideas?

@hadilsabbagh18 Do you need a transaction function, or can you use tempids (https://docs.datomic.com/cloud/transactions/transaction-processing.html#tempid-resolution)?

transaction functions don't resolve tempids

transaction functions (the ones that run inside datomic) return transaction data, which is later committed

@ghaid @shaun-mahood Understood. How do I create such a transaction atomically?

if you need to transact something compound in the same Datomic transaction, you just give it to transact: (d/transact conn {:tx-data [thing1 ... thing2.... thing3]})

the things can be arbitrary

transaction functions are something different and should be used to achieve specific purposes (they're like macros that run while the tx is being committed)

Thanks @ghadi. I have a one->many relationship between phone numbers and persons. How would I do that in a single transaction?

I don't mean to brush off the question, but you should really go through the tutorials

all of this is covered

and I'll do a bad job explaining 😃

you're using Cloud?

I've got an example I can paste in here - will redact it quickly and throw it in a thread (the docs are great, but I sometimes need a few extra examples to figure things out the first time)

Thanks @ghadi. I have gone through all the tutorials and the videos.

@shaun-mahood you can email it to me at <mailto:[email protected]|[email protected]>

if you wish.

https://docs.datomic.com/cloud/transactions/transaction-processing.html#tempid-resolution

linking tempids together is how you assert relationships between things

@ghadi. The problem is that i need to commit data atomically, not how to retrieve tempids.

[{:db/id "customer1"
 :customer/name "hadils"}
{:db/id "customer2"
 :customer/name "ghadi"
 :friends/with "customer1"}]

things sent in the same tx-data are committed together

in that example, two new entities are created, and the second entity points to the first entity

two tempids "customer1" "customer2" will be resolved into two entity-ids when committed

you can send in arbitrary graphs of entities in the same tx

@ghadi. I am with you. So I need to not use tempids then, I need some other reference for a one-many relationship.

(those are tempids above)

if you have a unique ID you can send that in instead of the tempid -- but the end result is the same: datomic needs to know what entities you're asserting things about

@ghadi. yes i see that now. is :firends/with a fre value type?

yes

thanks. that answers my question.

this got me as well. in cloud, tempids are just strings in the :db/id

https://docs.datomic.com/cloud/transactions/transaction-data-reference.html#identifier

the tx data grammar at the top of that page is useful, along with the examples

I think my biggest stumbling blocks in learning Datomic have all been related to how simple it is at the core

What about one to many relationships?

"cardinality many" attributes can be asserted in a similar way

Ok

:friends/with [joe hadils...]

in the transaction data

Thanks a lot @ghadi !