Newer versions can't clear columns which are used in default expressions for other columns. Maybe it's caused by https://github.com/ClickHouse/ClickHouse/issues/6913

CH version 20.5.2


create database Temp;
create table Temp.Test (`impression_id` String,`impression_id_compressed` FixedString(16) DEFAULT UUIDStringToNum(substring(impression_id, 1, 36)), `impression_id_hashed` UInt16 DEFAULT reinterpretAsUInt16(impression_id_compressed), `event_date` Date ) ENGINE = MergeTree(event_date, impression_id_hashed, (event_date, impression_id_hashed), 8192);
alter table Temp.Test clear column `impression_id` in partition '202001';


Received exception from server (version 20.5.2):
Code: 44. DB::Exception: Received from ch7r1.local:9000. DB::Exception: Cannot drop column `impression_id`, because column `impression_id_compressed` depends on it. 




Older versions (tested with 19.17.4 and 20.3.5):

CREATE DATABASE Temp;
create table Temp.Test (`impression_id` String,`impression_id_compressed` FixedString(16) DEFAULT UUIDStringToNum(substring(impression_id, 1, 36)), `impression_id_hashed` UInt16 DEFAULT reinterpretAsUInt16(impression_id_compressed), `event_date` Date ) ENGINE = MergeTree(event_date, impression_id_hashed, (event_date, impression_id_hashed), 8192);
alter table Temp.Test clear column `impression_id` in partition '202001';

ALTER TABLE Temp.Test
    CLEAR COLUMN impression_id     IN PARTITION '202001'


Ok.

return;
                throw Exception("Wrong index name. Cannot find index " + backQuote(index_name) + " to drop.", ErrorCodes::BAD_ARGUMENTS);
            }
            metadata.secondary_indices.erase(erase_it);
        }
    }
    else if (type == ADD_CONSTRAINT)
    {
        if (std::any_of(
                metadata.constraints.constraints.cbegin(),
                metadata.constraints.constraints.cend(),
                [this](const ASTPtr & constraint_ast)
                {
                    return constraint_ast->as<ASTConstraintDeclaration &>().name == constraint_name;
                }))
        {
            if (if_not_exists)
                return;
            throw Exception("Cannot add constraint " + constraint_name + ": constraint with this name already exists",
                        ErrorCodes::ILLEGAL_COLUMN);
        }
        auto insert_it = metadata.constraints.constraints.end();
        metadata.constraints.constraints.emplace(insert_it, std::dynamic_pointer_cast<ASTConstraintDeclaration>(constraint_decl));
    }
    else if (type == DROP_CONSTRAINT)
    {
        auto erase_it = std::find_if(
                metadata.constraints.constraints.begin(),
                metadata.constraints.constraints.end(),
                [this](const ASTPtr & constraint_ast)