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cassandracountercql3nosql

Counter Vs Int column in Cassandra?

I'm new in Cassandra. I can't understand what is the advantage of using counter in a table (or even in a different table if the non-counter columns are not part of the composite PRIMARY KEY)? Why we don't use a column with Int type, when I will have some statements like x=x++; what is the different between using int or counter?
Is that possible to use increments or decrements for Int Type in Cassandra at all?

Solution

  • Why we don't use a column with Int type, when I will have some statements like x=x++; what is the different between using int or counter?

    Because using a normal Int column would require read-before-write and lock for operations like x=x++

    Indeed, for a distributed database when you can have concurrent updates on the same value, the only way to guarantee consistent behaviour for x=x++ is:

    1. lock the current record
    2. read the current value of x, increment it by 1
    3. write back the new value of x
    4. release the lock

    Counter type allows concurrent increment/decrement on the value without neither requiring read-before-write nor locking