title: SAP HANA OOM error on UNION
body: <p>I have a table with 28mn records which on union (on a graphical calc view on HANA 2 SP2) with a view returning 5000 records goes into memory dumps. I've tried a SQL union all and it still doesn't work. There is no logic in the union view.</p>
  
  <p>A select top 1000 on the table returns data in &lt;1s and the the view with 5k records brings back data in 2s. When I union these 2 with no logic whatsover - even after switching the aggregation node to projection, it still runs out of memory. What am I missing here?</p>
  
  <p>transaction rolled back by an internal error: Allocation failed ; $size$=2048; $name$=SearchAlloc; $type$=pool; $inuse_count$=11184979; $allocated_size$=20190632592; $alignment$=16</p>