Verified that this happens after
PHOENIX-3271 Distribute UPSERT SELECT across cluster. https://git-wip-us.apache.org/repos/asf?p=phoenix.git;a=commitdiff;h=accd4a276d1085e5d1069caf93798d8f301e4ed6
Upsert 2M rows (CSV is available at https://goo.gl/OsTSKB) that will create ~4 regions on a single RS and then create index with data present
From RS log
Prior to the change index creation succeeds with as little as 2GB heap.