We are using availability groups in SQL 2019 Enterprise edition. We are using the enterprise feature to allow the AG secondary nodes to be in Read-only mode, and then running reporting queries against the secondary by connecting to the listener with
For locking and performance reasons, we have some queries that run using
Read Uncommitted isolation level on the primary.
It seems that on the secondary all isolation levels are converted to RCSI regardless of specified locking/isolation level - presumably because it's essential that there are no locks that could block the AG sync.
Is it possible to run queries in Read Uncommitted on the secondary, which would presumably also ensure no locks are taken but, and, under some circumstances can perform better, or will it always have to be RCSI for queries on the Read-Only secondary?