earth7316
Hi all
I have a Phoenix application that has it’s own Postgres database and also needs to communicate to a read only database on a different machine to get catalog type of data. This works fine and I’ve setup my application with two Repo’s and can retrieve data.
The problem I’m running into is with running
mix test
this is attempting to use a test database that doesn’t exist (and can’t really as the read only database is a huge legacy system of record for multiple applications). I know with ecto.migrate I can pass a -r flag to say which Repo to use but when running tests that flag doesn’t seem to exist.
Can anyone point me to some documentation on this?
BTW even the -r flag is a bit wonky in my opinion. I would think having a flag in the configuration to say the database is read only so don’t try and use it for generators, migrations or tests would be a much cleaner integration and potentially avoid risk of accidentally running mix ecto.reset and having it cascade inadvertently to a database that wasn’t meant for dropping (I realize you could have a different db user that’s read only but for development it’s not always easy to get an operations team member to do things like add users to a database).
Thanks for any help.
Where Next?
Trending in Questions
Other Trending Topics
Latest Phoenix Threads
Latest on Elixir Forum
Sponsor Spotlight
Supporting innovation across the BEAM ecosystem.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #library
- #deployment
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #elixirconf
- #channels
- #exunit
- #discussion
- #code-sync
- #podcasts
- #javascript
- #onsite
- #dialyzer
- #docker
- #authentication
- #umbrella
- #full-time-contract
- #podcasts-by-brainlid
- #ecto-query
- #ai
- #elixirconf-us
- #blog-post
- #elixir-ls
- #phoenix_html
- #iex
- #graphql
- #genstage
- #websockets
- #supervisor
- #advent-of-code
- #distillery
- #processes
- #api
- #forms
- #elixirconf-eu
- #metaprogramming
- #hex
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Elixir, Erlang & BEAM conferences from Code Sync - join us in 2026!
Practical resources that improve the lives of professional developers.
Bringing learning, work and compliance together since 1987.
**Building the future of software with AI, trust, and human connection.**
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"
Showing Posts 1 to 5- Show Best Posts
- Show All (oldest first)
- Show All (newest first)
NobbZ
Create a dummy database for that read-only one.
Unless your tests are directly or indirectly relying on data in that database it will work if you leave it empty I think. If not you need to fill in some stub data.
earth7316
Thanks Nobbz that works but is kind of wonky for my needs. I discovered though that I can modify the aliases in mix.exs to do what I need for this scenario which is migrations, reset, create, drop ONLY apply to my database and not my read replica that I use for ancillary data and is not part of this applications CRUD operations. So I did this and it works great
josevalim
There is a configuration in your config files named ecto_repos. If you don’t pass the
--repo/-rflags, only the repositories listed there will be set up, migrated, etc. You should be able to set the config to an empty list, change it per environment, etc.earth7316
Ah thanks Jose - much better!!
vineetv2821993
Sorry for joining late. Follow this post: Using Multiple DBs in Phoenix · Blog