Github user ilooner commented on a diff in the pull request:
https://github.com/apache/drill/pull/1164#discussion_r174343151
--- Diff: exec/vector/src/main/codegen/templates/VariableLengthVectors.java
---
@@ -514,6 +516,22 @@ public boolean isNull(int index){
* The equivalent Java primitive is '${minor.javaType!type.javaType}'
*
* NB: this class is automatically generated from ValueVectorTypes.tdd
using FreeMarker.
+ * </p>
+ * <h2>Contract</h2>
+ * <p>
+ * Variable length vectors do not support random writes. All set
methods must be called for with a monotonically increasing consecutive sequence
of indexes.
--- End diff --
Thanks for bringing this up. I'm sharing a design doc on the dev list
tomorrow or the day after about how I plan to refactor HashAgg. It will cover
how to facilitate unit tests and how to change the memory handling to use a
deterministic calculator like the SortMemoryManager and soon to be introduced
HashJoinMemoryCalculator (instead of catch OOMs). Perhaps you could comment on
the doc about how to set ourselves up to fix this case.
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