Creating a counter table
A counter is a special column for storing a number that is changed in increments.
cassandra.yaml
The location of the cassandra.yaml file depends on the type of installation:Package installations | /etc/dse/cassandra/cassandra.yaml |
Tarball installations | installation_location/resources/cassandra/conf/cassandra.yaml |
A counter is a special column used to store an integer that is changed in increments.
- Keeping track of the number of web page views received on a company website
- Keeping 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. At any given moment in DataStax Enterprise, the counter value could be stored in the memtable, commit log, 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.