Describe the problem

The syntax ALTER INDEX IF EXISTS does not seem to work. It seems its implementation was forgotten in #2034

To Reproduce

Run this statement:

alter index if exists i1 rename to i2;

I'm expecting it to be ignored, but I'm getting:

SQL Error [42704]: ERROR: index "i1" does not exist

Environment:

• CockroachDB version: CockroachDB CCL v19.2.0-rc.4 (x86_64-unknown-linux-gnu, built 2019/11/05 20:40:29, go1.12.12)
• Server OS: Linux in DOcker
• Client app: JDBC