What's the difference between coalesce() and repartition()?

[Ryan_Chynoweth]

Repartition triggers a full shuffle of data and distributes the data evenly over the number of partitions and can be used to increase and decrease the partition count. Coalesce is typically used for reducing the number of partitions and does not require a shuffle. According to the inline documentation of coalesce you can use coalesce to increase the number of partitions but you must set the shuffle argument to true. Please note that unlike repartition, coalesce does not guarantee equal partitions.