MariaDB ColumnStore has a hard limit of 4096 columns per table.
However, it's likely that you run into other limitations before hitting that limit, including:
Row size limit of tables. This varies, depending on the storage engine you're using. For example, InnoDB has a row size of 64KB which indirectly limits the number of columns.
Size limit of .frm files. Those files hold the column description of tables. Column descriptions vary in length. Once all column descriptions combined reach a length of 64KB, the table's .frm file is full, limiting the number of columns you can have in a table.
Given that, the maximum number of columns a ColumnStore table can effectively have is around 2000 columns.
