
create table test1 (a Float32,  b Float32 ) engine = MergeTree order by a ;
insert into test1 values (0.1,0.1), (0.2,0.2);
select count() from test1 where b = 0.1;
0 
select count() from test1 where b = toFloat32(0.1);
1
select count() from test1 where a > 0;
0
select count() from test1 where a > 0.0;
2
select count() from test1 where b > 0;
2

version 22.1.3.7  

const ASTPtr & node,
    size_t & out_key_column_num,
    DataTypePtr & out_key_column_type,
    std::vector<const ASTFunction *> & out_functions_chain)
{
    /** By itself, the key column can be a functional expression. for example, `intHash32(UserID)`.
      * Therefore, use the full name of the expression for search.
      */
    const auto & sample_block = key_expr->getSampleBlock();
    
    String name = node->getColumnNameWithoutAlias();
    if (array_joined_columns.count(name))
        return false;
    auto it = key_columns.find(name);
    if (key_columns.end() != it)
    {
        out_key_column_num = it->second;
        out_key_column_type = sample_block.getByName(it->first).type;
        return true;