Cluster key in Nosql – Cassandra

k1 t1, k2 t2, ..., kn tn

create table clustering (
 x text,
 k1 text,
 k2 int, 
 k3 timestamp,
 y text,
 primary key (x, k1, k2, k3)
);

insert into clustering (x, k1, k2, k3, y) values ​​('x','a', 1, '2013-09-10 14:00+0000 ', '1');
insert into clustering (x, k1, k2, k3, y) values ​​('x','b', 1, '2013-09-10 13:00+0000', '1');
insert into clustering (x, k1, k2, k3, y) values ​​('x','a', 2, '2013-09-10 13:00+0000', '1 ');
insert into clustering (x, k1, k2, k3, y) values ​​('x','b', 1, '2013-09-10 14:00+0000', '1') ;

x | k1 | k2 | k3 | y
---+----+----+------------------------- -+---
 x | a | 1 | 2013-09-10 14:00:00+0000 | 1
 x | a | 2 | 2013-09-10 13:00:00+ 0000 | 1
 x | b | 1 | 2013-09-10 13:00:00+0000 | 1
 x | b | 1 | 2013-09-10 14:00:00+0000 | 1

On a given physical node, the rows of a given partition key are stored in the order triggered by the cluster key, so that the rows in the cluster order are retrieved Especially effective. http://cassandra.apache.org/doc/cql3/CQL.html#createTableStmt What sort of clustering key causes?

Assuming your cluster key is

k1 t1, k2 t2, ..., kn tn< /pre> 
where ki is the name of the i-th key and ti is the type of the i-th key. Then, the order data is stored in a dictionary sort, where each dimension is compared using this type of comparator. 
 
Then (a1, a2,..., an) (b1, b2,..., bn) If a1  to find all rows where ki = x. In fact, such a query is not allowed-the only allowed clustering key limit specifies zero or more clustering keys, from the first none The lost begins first. 
 
For example, consider the pattern
 
 
create table clustering (
 x text,
 k1 text,
 k2 int, 
 k3 timestamp,
 y text,
 primary key (x, k1, k2, k3)
);
If you did the following insert:< /p> 
insert into clustering (x, k1, k2, k3, y) values ​​('x','a', 1, '2013-09-10 14:00+0000 ', '1');
insert into clustering (x, k1, k2, k3, y) values ​​('x','b', 1, '2013-09-10 13:00+0000', '1');
insert into clustering (x, k1, k2, k3, y) values ​​('x','a', 2, '2013-09-10 13:00+0000', '1 ');
insert into clustering (x, k1, k2, k3, y) values ​​('x','b', 1, '2013-09-10 14:00+0000', '1') ;
Then they are stored on the disk in this order (the order of clusters returned from x ='x' select *):

x | k1 | k2 | k3 | y
---+----+----+------------------------- -+---
 x | a | 1 | 2013-09-10 14:00:00+0000 | 1
 x | a | 2 | 2013-09-10 13:00:00+ 0000 | 1
 x | b | 1 | 2013-09-10 13:00:00+0000 | 1
 x | b | 1 | 2013-09-10 14:00:00+0000 | 1
k1 sorting dominates, then k2, then k3.