AWS RDS Postgres giving error while setting “hnsw.ef_search” parameter on DB or User Level

Hello everyone,

I'm currently utilizing the pgvector extension for storing vector embeddings in a PostgreSQL database. Additionally, I've implemented the hnsw indexing algorithm for indexing these vectors. My goal is to set the ef_search parameter either at the user level or the database level. However, when I attempt to execute the SQL queries for this purpose, PostgreSQL returns an error stating “permission denied to set parameter 'hnsw.ef_search'”, even though I am using the postgres super-user account.

Here are the queries I've tried:

ALTER DATABASE mydb SET hnsw.ef_search = 500;

And

ALTER USER myuser SET hnsw.ef_search = 500;

Some additional information:

1. Attempting to set a random named variable results in the error: “ERROR: unrecognized configuration parameter 'axax'”.
2. Trying to set another valid variable, updates successfully at the database level.

Any insights or assistance on resolving this issue would be greatly appreciated.

Thank you.