CODEWITHSUNDEEP
cassandraprimary-keypartitionlwt
Elnaz
Elnaz

Reputation: 2890

How the LWT- Light Weight Transaction is working when we use IF NOT EXIST?

The question is that, When we use 

    INSERT INTO USERS (login, email, name, login_count)        
    values ('jbellis', '[email protected]', 'Jonathan Ellis', 1)        
    IF NOT EXISTS

in IF NOT EXIST exactly which columns are compared together? primary key(partition-key + clustering-key)? or just partition-key?

Upvotes: 2

Views: 412

Answers (1)

doanduyhai
doanduyhai

Reputation: 8812

Here is a diagram of the 4 phases of LWT: http://www.slideshare.net/doanduyhai/cassandra-introduction-nantesjug/89

The original blog post is here: http://www.datastax.com/dev/blog/lightweight-transactions-in-cassandra-2-0

exactly which columns are compare together? primary key? partition-key?

The whole primary key is checked on disk. In the example it is a simple primary key so it's also the partition key, e.g. login column

Upvotes: 1

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