Clojurians Log v2

<https://en.wikipedia.org/wiki/Codd%27s_12_rules> You're in good company :slightly_smiling_face: &gt; *Rule 4:* _Dynamic <https://en.wikipedia.org/wiki/Online|online>_ _<https://en.wikipedia.org/wiki/Database_catalog|catalog> based on the relational model_: &gt; The data base description is represented at the logical level in the same way as ordinary data, so that authorized users can apply the same relational language to its interrogation as they apply to the regular data.

@filipematossilva we use a cell-based architecture where we run around 100 customers per dedicated server. Each server runs its own Datomic transactor pair. Sqlite is used as storage. We also run one Docker container per customer. Every customer has its own Datomic database. If you have a multi-tenant Clojure web application you can probably run way more Datomic databases per cell / server.

@maxweber so 1 sqlite db - 1 transactor pair - 100 dbs, right? how have you been finding sqlite for this case btw?

There’s some prior discussions about this in the datomic forum, but at least one limitation I know of is that the per-database schema is held in memory

@filipematossilva for pro see: https://docs.datomic.com/operation/capacity.html#multiple-databases. The general gist is current datomic Pro it is not recommended to run multiple large and/or mission critical databases on a single transactor pair. Because of competing resources, but mostly the process must hold a sum of every databases memory index.

For Cloud we support multi tenancy quite nicely but there is a catalog name limit that you would encounter if you created around 10,000 datomic level databases on the same Cloud system. I am not certain on the precise number but I believe it might be 10,000. Confirming.

And usual caveat applied that in Cloud there are lots of scaling considerations based on the specifics your thousands of DBs and their usage.

Hey thanks for taking the time to respond! I was thinking pro more than cloud, and knowing about that detail makes a lot of sense why it's hard. Still sounds a bit like it'd be similar to a single large db of similar total memory index size.

also increases startup time I think

@filipematossilva yes, 1 sqlite db - 1 transactor pair - 100 dbs. No problems with Sqlite so far. However, I would prefer to have one Sqlite db file per customer, since it would make migrating one customer to another cell more straight-forward, then to use the Datomic backup mechanism for it.