Deleting Column Families

You can delete a column family (except for the default column family) in a JSON table with the Admin.deleteFamily() Java method.

Important: Starting in the 6.0 release, you cannot delete a column family from a JSON table.

Permissions Required

The readAce and writeAce permissions on the volumes where the JSON tables are located. For information about how to set permissions on volumes, see Setting Whole Volume ACEs.

Behavior

The data that is in the specified column family is deleted. If the column family is followed by one or more column families in a hierarchy, the other column families in the hierarchy are unaffected and still accessible. For example, if column family CF1 at path a.c is followed by column family CF2 at path a.c.f, CF2 remains accessible and only the data in CF1 is deleted.

Before deleting the column family CF1 at a.c After deleting the column family CF1 at a.c
{
 "a" : {
         "b" : "value_b",
         "c" : {
                 "d" : "value_d",
                 "e" : "value_e",
                 "f" : {
                         "g" : "value_g",
                         "h" : "value_h"
                       }
                }
       }
}
{
 "a" : {
         "b" : "value_b",
         "c" : {
                 "d" : "",
                 "e" : "",
                 "f" : {
                         "g" : "value_g",
                         "h" : "value_h"
                       }
                }
       }
}

Example of using the Admin.deleteFamily() method

public void deleteColumnFamily(String tablePath, String familyName) throws DBException {
    try (Admin admin = MapRDB.newAdmin()) {
      if (admin.tableExists(tablePath)) {
        admin.deleteFamily(tablePath, familyName);
      }
    }
}
Parameter Description
tablePath The path of the table in the MapR file system. See the "Table Paths" section in MapR Database JSON Tables.
familyName The name of the column family to delete. You cannot delete the default column family. If familyName is equal to "default", the API returns an exception.