Cassandra Data Type 1 – uuid, timestamp

Data Type

Following documentation is quite good explanation about Data Type.

• Tutorial Point
• Cassandra CQL

uuid

I’m using MySQL. I use bigint unsigned autoincrement setting for count primary key.

For cassandra, there is no exact equivalent. Cassandra is distributed use, so autoincrement is not exactly same use case.

uuid becomes a kind of unique key for this role. of course uuid does not have order like incremental key

Example

Create table members (
  uid uuid primary key,
  name varchar
);
INSERT INTO members(uid, name) VALUES (uuid(), 'Ore');

uuid()  :   UUID Type 4, generate uuid

timestamp

This is same meaning as MySQL.

Example

Create table entry(
  uid uuid primary key,
  name varchar,
  time timestamp
);

INSERT INTO entry (uid, name, time) VALUES (uuid(), 'Taro', toTimestamp(now()));

toTimestamp(now()) generates current time

You can see data like

SELECT * FROM entry;

uid                                  | name | time
--------------------------------------+------+---------------------------------
 400aa338-41bb-42a7-a5b4-15e380f666a5 | Taro | 2019-10-13 02:41:19.450000+0000