Hadoop is optional only for testing. To do anything on any scale, you will also need hadoop.
Running without hadoop means that you are using the pig locally. This basically means that all the data is processed by the same pig process in which you work. This works great with single node and sample data.
When working with any significant amount of data or multiple machines, you want to run pigs in chaos mode. By running debugger control tracks on your cassandra nodes, you can take advantage of benefits that reduce the cost of the card by providing workload balancing and using data localization to reduce network transfer.
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