Hello, Is there a way I can access PostgreSQL sequence nextval from Elixir Ecto query? I would be very grateful for your response. Thanks. Jerry

Ecto.Query — Ecto v3.14.0 If you need an escape hatch, Ecto provides fragments (see Ecto.Query.API.fragment/1 ) to inject SQL (and non-SQL) fragments into queries.

In case someone came across this question, a concrete solution is using fragment but it should be in from import Ecto.Query MyApp.Repo.one( from seq in fragment("SELECT nextval('slugs_id_seq') as id"), select: seq.id )

I was messing around with this recently, and I was having difficulty getting the next available sequence ID without incrementing the sequence in situations where there may or not be any rows in the table (e.g. during testing). I came up with this, so I’m adding it to the pile in case it may be usef…

Interesting approach @arcanemachine ! A word of caution about retrieving the last value - there’s an important concurrency consideration to keep in mind. The get_next_available_id approach can lead to multiple processes request an ID simultaneously and get the same ID.

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PostgreSQL sequence nextval

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jerry January 31, 2019, 9:13am 3

Hello @gcauchon,

Thanks for your response.

Regards,

Jerry