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https://issues.apache.org/jira/browse/DRILL-6234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16397932#comment-16397932
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ASF GitHub Bot commented on DRILL-6234:
---------------------------------------
Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/1164#discussion_r174328025
--- Diff: exec/vector/src/main/codegen/templates/VariableLengthVectors.java
---
@@ -514,6 +516,22 @@ public boolean isNull(int index){
* The equivalent Java primitive is '${minor.javaType!type.javaType}'
*
* NB: this class is automatically generated from ValueVectorTypes.tdd
using FreeMarker.
+ * </p>
+ * <h2>Contract</h2>
--- End diff --
Might be worth summarizing how to use this:
1) Write to values sequentially. Fixed-width vectors allow random access,
but special care is needed.
2) Keep track in client code of the total time count. Call
`setValueCount()` once the vector is full to set the final value. (The vector
does not know its count while a write is in progress.)
3) Either take responsibility for allocating enough memory, or call the
`setSafe()` methods to automatically extend the vector.
4) Once vectors are written, they are immutable; no additional writes of
any kind are allowed to that vector.
> Improve Documentation of VariableWidthVector Behavior
> -----------------------------------------------------
>
> Key: DRILL-6234
> URL: https://issues.apache.org/jira/browse/DRILL-6234
> Project: Apache Drill
> Issue Type: Improvement
> Reporter: Timothy Farkas
> Assignee: Timothy Farkas
> Priority: Major
>
> Doing the following will throw an Index out of bounds exception.
> {code}
> final VarCharVector vector = new VarCharVector(field, allocator);
> vector.allocateNew();
> vector.getMutator().setValueCount(100);
> {code}
> The expected behavior is to resize the array appropriately. If an index is
> uninitialized you should not call get for that index.
> {code}
> at
> org.apache.drill.exec.memory.BoundsChecking.checkIndex(BoundsChecking.java:80)
> at
> org.apache.drill.exec.memory.BoundsChecking.lengthCheck(BoundsChecking.java:86)
> at io.netty.buffer.DrillBuf.chk(DrillBuf.java:114)
> at io.netty.buffer.DrillBuf.getInt(DrillBuf.java:484)
> at
> org.apache.drill.exec.vector.UInt4Vector$Accessor.get(UInt4Vector.java:432)
> at
> org.apache.drill.exec.vector.VarCharVector$Mutator.setValueCount(VarCharVector.java:729)
> at
> org.apache.drill.exec.vector.VarCharVectorTest.testExpandingNonEmptyVectorSetValueCount(VarCharVectorTest.java:97)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at
> com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
> at
> com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
> at
> com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
> at
> com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
> {code}
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