dev=> create table t(v int, ts timestamptz);
CREATE_TABLE
dev=> create table mock_time(now timestamp);
CREATE_TABLE
dev=> create materialized view mv as select * from t where ts > (select max(now) from mock_time);
ERROR:  Failed to run the query

Caused by:
  Not supported: streaming nested-loop join
HINT: The non-equal join in the query requires a nested-loop join executor, which could be very expensive to run. Consider rewriting the query to use dynamic filter as a substitute if possible.
See also: https://docs.risingwave.com/docs/current/sql-pattern-dynamic-filters/