Extensions in ash_postgres database

samoloth

Hi,

since my project will require some analytics, I’ve decided to use Postgres + DuckDB via pg_duckdb extension. I’ve spinned up an official pgduckdb container, set up credentials, run mix ash.reset, added pg_duckdb to installed_extensions/0 and finally run mix ash.codegen install_pg_duckdb + mix ash.migrate, but I end up with:

Getting extensions in current project...
Running migration for AshPostgres.DataLayer...

09:31:07.612 [info] == Running 20251218083057 MyApp.Repo.Migrations.InstallPgDuckdbExtensions1.up/0 forward

09:31:07.619 [info] execute "CREATE EXTENSION IF NOT EXISTS \"pg_duckdb\""

09:31:07.670 [info] == Migrated 20251218083057 in 0.0s
** (Postgrex.Error) ERROR 42P01 (undefined_table) relation "schema_migrations" does not exist

    query: INSERT INTO "schema_migrations" ("version","inserted_at") VALUES ($1,$2)
    (ecto_sql 3.13.3) lib/ecto/adapters/sql.ex:1108: Ecto.Adapters.SQL.raise_sql_call_error/1
    (ecto 3.13.5) lib/ecto/repo/schema.ex:1000: Ecto.Repo.Schema.apply/4
    (ecto 3.13.5) lib/ecto/repo/schema.ex:500: anonymous fn/15 in Ecto.Repo.Schema.do_insert/4
    (my_app 0.1.0) lib/my_app/repo.ex:2: MyApp.Repo.insert/2
    (ecto_sql 3.13.3) lib/ecto/migrator.ex:338: anonymous fn/6 in Ecto.Migrator.async_migrate_maybe_in_transaction/7
    (my_app 0.1.0) lib/my_app/repo.ex:2: anonymous fn/1 in MyApp.Repo."transaction (overridable 1)"/2
    (ecto 3.13.5) lib/ecto/repo/transaction.ex:11: anonymous fn/3 in Ecto.Repo.Transaction.transact/4
    (ecto_sql 3.13.3) lib/ecto/adapters/sql.ex:1468: anonymous fn/3 in Ecto.Adapters.SQL.checkout_or_transaction/4

Here are some additional logs:

$ psql -U duck
psql (18.1 (Debian 18.1-1.pgdg12+2))
Type "help" for help.

duck=# \dx
                           List of installed extensions
   Name    | Version | Default version |   Schema   |         Description          
-----------+---------+-----------------+------------+------------------------------
 pg_duckdb | 1.1.0   | 1.1.0           | public     | DuckDB Embedded in Postgres
 plpgsql   | 1.0     | 1.0             | pg_catalog | PL/pgSQL procedural language
(2 rows)

duck=# \c my_app_dev 
You are now connected to database "my_app_dev" as user "duck".
my_app_dev=# \dx
                          List of installed extensions
  Name   | Version | Default version |   Schema   |         Description          
---------+---------+-----------------+------------+------------------------------
 plpgsql | 1.0     | 1.0             | pg_catalog | PL/pgSQL procedural language
(1 row)

my_app_dev=# SELECT * FROM schema_migrations;
    version     |     inserted_at     
----------------+---------------------
 20251210094714 | 2025-12-18 08:28:00
(1 row)

As you can see, schema_migrations table exists.

2 comments

/ash #postgres #ash-postgres

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2025-12-22 12:08:46 UTC

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samoloth

Ok, I works with ddl transaction disabled. Question is whether it should be disabled by default when it comes to extensions?

Post #1

zachdaniel

Creator of Ash

Hmm…it could yes? It must be a restriction of duck db though because we don’t have that issue with Postgres. Makes me wonder if Postgres can actually transactionally install an extension. Feels like probably not.

With that said we define functions etc. which we’d want to be transactional.

Post #2

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