Sequence generators

Overview

Sequence Generator is used to create unique primary key values, replace missing primary keys, or cycle through a sequential range of numbers. In Etlworks the sequence numbers can be generated programmatically using one of the available sequence generators.

UniqueNumber

This class allows developers to generate a timestamp-based unique and sequential long number.  The actual number is generated using the following algorithm:

(System.currentTimeMillis() << 20) + n, where n is incremented by 1 on each call.

The same instance of the UniqueNumber class must be used to generate the consistently incremented sequence.

How to use UniqueNumber

var uniqueNumber = etlConfig.getValue("uniqueNumber");

if (uniqueNumber == null) {
    uniqueNumber = new com.toolsverse.util.UniqueNumber();
    etlConfig.setValue("uniqueNumber", uniqueNumber);
}

value = uniqueNumber.nextNumber();

RedisSequenceGenerator

The instance of this class uses Redis to generate the unique sequential numbers so it can be used simultaneously by multiple flows. The class makes a call to the Redis each time it needs to generate a new number. It can generate up to 10K numbers per second.   

How to use RedisSequenceGenerator

com.toolsverse.io.RedisSequenceGenerator.instance().nextNumber(key, startValue);

where the key is any string, for example, table name and the startValue is a starting sequence number, which can be any not negative long number. 

Example

var seq = com.toolsverse.io.RedisSequenceGenerator.instance().nextNumber('my_table_name', 1);