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https://issues.apache.org/jira/browse/DRILL-5517?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16068504#comment-16068504
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ASF GitHub Bot commented on DRILL-5517:
---------------------------------------
Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/840#discussion_r124813604
--- Diff: exec/vector/src/main/codegen/templates/NullableValueVectors.java
---
@@ -674,6 +764,14 @@ public void reset(){
setCount = 0;
<#if type.major = "VarLen">lastSet = -1;</#if>
}
+
+ @Override
+ public void exchange(ValueVector.Mutator other) {
--- End diff --
How does swapping the value count exchange the buffer ? The name
'exchange' indicates more than what this method is doing. The JIRA description
says the 'exchange is for vectors within a single operator' but I am not sure
how that is enforced considering the ValueVector.Mutator that is passed in
could belong to any ValueVector. So, essentially we are trusting the caller to
use it only for specific cases.
> Provide size-aware set operations in value vectors
> --------------------------------------------------
>
> Key: DRILL-5517
> URL: https://issues.apache.org/jira/browse/DRILL-5517
> Project: Apache Drill
> Issue Type: Improvement
> Affects Versions: 1.11.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Labels: ready-to-commit
> Fix For: 1.11.0
>
>
> DRILL-5211 describes a memory fragmentation issue in Drill. The resolution is
> to limit vector sizes to 16 MB (the size of Netty memory allocation "slabs.")
> Effort starts by providing "size-aware" set operations in value vectors which:
> * Operate as {{setSafe()}} while vectors are below 16 MB.
> * Throw a new, specific exception ({{VectorOverflowException}}) if setting
> the value (and growing the vector) would exceed the vector limit.
> The methods in value vectors then become the foundation on which we can
> construct size-aware record batch "writers."
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