Creating Column Families

Add a column family to the TableDescriptor object before passing that object to the createTable() method.

Restriction

If any existing column family in a JSON table, including the default column family, uses a time-to-live that is greater than 0, you cannot create any additional column families in that table. See Setting TTL for Data.

Permissions Required

• readAce and writeAce on the volume
• lookupdir on directories in the path
• createrenamefamilyperm on the table

Example

Here is an example of using the API to create two column families -- the default column family and a custom column family -- during the creation of a table:

/* Create a TableDescriptor for the table to create,
   passing in the path of the table. */
TableDescriptor tableDescriptor = MapRDB.newTableDescriptor(tablePath);

/* Create a FamilyDescriptor for the default column family.
   When you create a table with the API, you must also create
   the default column family.
   After creating the FamilyDescriptor, add it to 
   the TableDescriptor. */
FamilyDescriptor defaultfamilyDesc = MapRDB.newDefaultFamilyDescriptor();
tableDescriptor.addFamily(defaultfamilyDesc);

/* Create a FamilyDescriptor for the custom column family
   to create. The setJsonFieldPath() method specifies the field
   at which to create the column family.
   After creating the FamilyDescriptor, add it to 
   the TableDescriptor. */
FamilyDescriptor familyDescriptor = MapRDB.newFamilyDescriptor()
  .setName("CF1")
  .setJsonFieldPath("a.b");
tableDescriptor.addFamily(familyDescriptor);

// Pass the TableDescriptor to the Admin.createTable() method.
public void createJSONTable(String tablePath, TableDescriptor tableDescriptor) throws DBException {
  try (Admin admin = MapRDB.newAdmin()) {
    if (!admin.tableExists(tablePath)) {
      admin.createTable(tableDescriptor);
    }
  }
}

Alternative Method

You can also create column families in JSON tables by running the command table cf create.