How to create Secondary Index?

cqlsh:ks> -- Note : Secondary index are not recommended for, #76 #94
cqlsh:ks> -- - Columns with High Cardinality
cqlsh:ks> -- - Columns with Low Cardinality
cqlsh:ks> -- - Columns that are frequently updated or deleted
cqlsh:ks> -- ** Better to have a denormalized table rather than secondary
cqlsh:ks> --    index #77
cqlsh:ks> -- # a120 > a93
cqlsh:ks>
cqlsh:ks> -- Create Table
cqlsh:ks> drop table student;
cqlsh:ks> drop type mark;
cqlsh:ks>
cqlsh:ks> create type mark (
      ...    math text,
      ...    science text
      ... );
cqlsh:ks>
cqlsh:ks> create table student(
      ...    name text,
      ...    class text,
      ...    month_v_attendance map<text, text>,
      ...    week_v_attendance map<text, text>,
      ...    subjects frozen<mark>,
      ...    primary key(name)
      ... );
cqlsh:ks>
cqlsh:ks> -- Insert Data
cqlsh:ks> insert into
      ...    student( name, class, subjects, month_v_attendance,
      ...             week_v_attendance)
      ... values('bob', '3rd', {math: '70', science: '80'},
      ...       {'jan': '90%'}, {'3rdweek' : '90%'});
cqlsh:ks>
cqlsh:ks> select * from student;

 name | class | month_v_attendance | subjects                    | week_v_attendance
------+-------+--------------------+-----------------------------+--------------------
  bob |   3rd |     {'jan': '90%'} | {math: '70', science: '80'} | {'3rdweek': '90%'}

(1 rows)
cqlsh:ks>
cqlsh:ks> select * from student where class='3rd';
InvalidRequest: Error from server: code=2200 [Invalid query] message="Cannot execute this query as it might involve data filtering and thus may have unpredictable performance. If you want to execute this query despite the performance unpredictability, use ALLOW FILTERING"
cqlsh:ks>
cqlsh:ks> -- Create Secondary Index
cqlsh:ks> create index classindex on student (class);
cqlsh:ks> select * from student where class='3rd';

 name | class | month_v_attendance | subjects                    | week_v_attendance
------+-------+--------------------+-----------------------------+--------------------
  bob |   3rd |     {'jan': '90%'} | {math: '70', science: '80'} | {'3rdweek': '90%'}

(1 rows)
-- SASI : SSTable Attached Secondary Index : Read more...#78