I have been shrinking old indices to reduce the amount of shards in our cluster, and I've noticed that the size of the indices before and after shrinking is not the same. The index size seems to have increased by 10 to 35%. At the same time, the amount of documents is exactly the same, as it should be expected.
Is there any reason for the significant change in size?
PS: I'm working on a 4 machine cluster with elastic 5.6.9, and most of the indices have been reduced from 5 shards to 1 (with one replica).