Understanding indexes
I come from the Node.js/MongoDB world and I'm learning Elixir and Ash.
I'm trying to ensure my resources/tables are correctly indexed (using AshPostgres). For that I have the following questions when using Ash:
1. Is the primary
:id attribute always indexed?
2. If one would like to make a partial index like [:user_id, :is_active] we should use custom_indexes inside the postgres definition, right? - would this then also be usable by queries that only filter on :user_id (but not filtering on the :is_active )?
3. Is identities attribute is only for making unique indexes?
4. Do I need to use the custom_indexes if I want to just index one attribute like created_at for example, or is there another preferred way of doing that?
Thanks in advance! Looking forward to build something cool with Ash 🙂Solution:Jump to solution
1. In Postgres at least, yes. Primary keys get a unique index.
2. This is more of a Postgres question than an ash question, I'd suggest looking at their docs. IIRC you're describing a composite index not a partial one (a partial one would be one with a where clause).
3. Yes. The identities have other uses but they imply a unique constraint and the migration generator will create one
4. Yes, that is how you'd do it 🙂...
2 Replies
Solution
1. In Postgres at least, yes. Primary keys get a unique index.
2. This is more of a Postgres question than an ash question, I'd suggest looking at their docs. IIRC you're describing a composite index not a partial one (a partial one would be one with a where clause).
3. Yes. The identities have other uses but they imply a unique constraint and the migration generator will create one
4. Yes, that is how you'd do it 🙂
Thanks for the clarification!