Postgres LISTEN/NOTIFY does not scale

Out of curiosity: Would appreciate if others can share what other things like AccessExclusiveLock should postgres users beware of?

What I already know

- Unique indexes slow inserts since db has to acquire a full table lock

- Case statements in Where break query planner/optimizer and require full table scans

- Read only postgres functions should be marked as `STABLE PARALLEL SAFE`

Can you provide more details? Inserting with unique indexes do not lock the table. Case statements are ok in where clause, use expression indexes to index it

> Unique indexes slow inserts since db has to acquire a full table lock

An INSERT never results in a full table lock (as in "the lock would prevent other inserts or selects on the table)

Any expression used in the WHERE clause that isn't indexed will probably result in a Seq Scan. CASE expressions are no different than e.g. a function call regarding this.

A stable function marked as "STABLE" (or even immutable) can be optimized differently (e.g. can be "inlined"), so yes that's a good recommendation.

https://pglocks.org/?pglock=AccessExclusiveLock is my go to reference.

My other reference for a slightly different problem is https://www.thatguyfromdelhi.com/2020/12/what-postgres-sql-c...