How about this? https://github.com/replikativ/datahike/blob/main/examples/basic/src/examples/schema.clj

Does this help you?

yes thank you !

There are solutions out there for migrations. I guess the main thing wrt migrations is idempotence, right? Maybe @UB95JRKM3 has a good answer?

https://clojurians.slack.com/archives/CB7GJAN0L/p1537193894000100

2018 though. there is wanderung as a project under the replikativ org on github but I don't know the current state of it. It is being worked on.

https://github.com/replikativ/wanderung-core

thanks timo for the answers

i also found this very interesting doc: https://github.com/replikativ/datahike/blob/main/doc/schema.md

Hi @U03BMTULBSL, so you mean something like https://github.com/avescodes/conformity or https://github.com/yogthos/migratus? I tried to create something based on conformity but it was not so easy since we have some internal differences to Datomic, so I only used the ideas of norms in our projects to ensure certain schemas to be in the database and to be applied. You can find an example https://github.com/lambdaforge/mtool-web/blob/main/src/clj/lf/administration/migrations.clj. I have some plans to move that into a separate library.

hey @UB95JRKM3 thanks for the tips; the docs of datahike mention that migrations aren't supported... you can only add fields and if you want to do more changes to the fields you need to create a new database and move your data

Yes, that's right. Changing things like schema names is not so easy on the index level and we don't have aliases yet.

And the change of value types and cardinality is also not so straightforward.

yes i understand that's nice to know so i can understand the consequences

@U03BMTULBSL I have written some code that handles that for me. You can have a look at it here: https://github.com/hhucn/decide3/blob/master/src/main/decide/server_components/db/migrate.clj It uses https://github.com/weavejester/ragtime, and it handles schema migration as well as more complex migrations, that restructure data.

thank you so this does the migration automatically ?

The upsert! function looks at the current schema. I calculate the difference of the current and the new schema. If there is a difference, I transact that difference. Then there is the migrate-data! function takes a seq of migrations like:

{:id "Rename :db/txUser to :tx/by"
  :up
  (fn [db]
    (for [[tx user] (d/q '[:find ?e ?user :where [?e :db/txUser ?user]] db)]
      [:db/add tx :tx/by user]))}

very interestingg thank you!