CQL for Cassandra 2.0

uuid and Timeuuid functions

Cassandra 2.0.7 and later includes the uuid() function. This function takes no parameters and generates a random Type 4 UUID suitable for use in INSERT or SET setatments.

Several Timeuuid functions are designed for use with the timeuuid type:

  • dateOf()

    Used in a SELECT clause, this function extracts the timestamp of a timeuuid column in a resultset. This function returns the extracted timestamp as a date. Use unixTimestampOf() to get a raw timestamp.

  • now()

    Generates a new unique timeuuid when the statement is executed. This method is useful for inserting values. The value returned by now() is guaranteed to be unique.

  • minTimeuuid() and maxTimeuuid()
    Returns a UUID-like result given a conditional time component as an argument. For example:
    SELECT * FROM myTable
       WHERE t > maxTimeuuid('2013-01-01 00:05+0000')
       AND t < minTimeuuid('2013-02-02 10:00+0000')
  • unixTimestampOf()

    Used in a SELECT clause, this functions extracts the timestamp of a timeuuid column in a resultset. Returns the value as a raw, 64-bit integer timestamp.

The min/maxTimeuuid example selects all rows where the timeuuid column, t, is strictly later than 2013-01-01 00:05+0000 but strictly earlier than 2013-02-02 10:00+0000. The t >= maxTimeuuid('2013-01-01 00:05+0000') does not select a timeuuid generated exactly at 2013-01-01 00:05+0000 and is essentially equivalent to t > maxTimeuuid('2013-01-01 00:05+0000').

The values returned by minTimeuuid and maxTimeuuid functions are not true UUIDs in that the values do not conform to the Time-Based UUID generation process specified by the RFC 4122. The results of these functions are deterministic, unlike the now function.

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