i use
my steps

1. create a new database ckdb on mysql, then create table t1(a int, primary key(a)); and insert some rows
2. SET allow_experimental_database_materialize_mysql=1; at clickhouse,
3. CREATE DATABASE ckdb ENGINE = MaterializeMySQL('127.0.0.1:3306', 'ckdb', 'root', 'A123b_456');
4. use ckdb and select * from t1 ok
5. create table dzm as select * from others in mysql ----> cannot see dzm in clickhouse, but if select * from t1, reports

Code: 48. DB::Exception: Received from localhost:9000. DB::Exception: The ckdb.dzm cannot be materialized, because there is no primary keys..

6. create table t2(a int,b int primary a);----> cannot see t2 in clickhouse, , but if select * from t1, reports

Code: 44. DB::Exception: Received from localhost:9000. DB::Exception: Sorting key cannot contain nullable columns.

7. if i drop ckdb and recreate it, all tables can be selected
7.if there are some 'bad' tables in a database, all tables in that database cannot be selected

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