Creating a counter table
A counter is a special column for storing a number that is changed in increments.
cassandra.yaml
- The cassandra.yaml file is located in the installation_location/conf directory.
A counter is a special column used to store an integer that is changed in increments.
- To keep track of the number of web page views received on a company website
- To keep track of the number of games played online or the number of players who have joined an online game
Tracking count in a distributed database presents an interesting challenge. In DataStax Distribution of Apache Cassandra™, at any given moment, the counter value may be stored in the Memtable, commit log, and/or one or more SSTables. Replication between nodes can cause consistency issues in certain edge cases.
- The primary key (can be one or more columns)
- The counter column
Many counter-related settings can be set in the cassandra.yaml file.
A counter column cannot be indexed or deleted. To load data into a counter column, or to
increase or decrease the value of the counter, use the UPDATE
command. The
database rejects USING TIMESTAMP
or USING TTL
when updating
a counter column.
- Use CREATE TABLE to define the counter and non-counter columns. Use all non-counter columns as part of the PRIMARY KEY definition.