adnan-bubalo opened a new issue, #812: URL: https://github.com/apache/arrow-java/issues/812
### Describe the bug, including details regarding any error messages, version, and platform. **Description:** When appending a `UnionVector` to an empty target `UnionVector`, [this](https://github.com/apache/arrow-java/blob/main/vector/src/main/java/org/apache/arrow/vector/util/VectorAppender.java#L556) while loop runs infinitely until the exception occurs: ``` org.apache.arrow.vector.util.OversizedAllocationException: Unable to expand the buffer ``` It seems to be a issue with the `UnionVector.getValueCapacity()` method. Logging the capacity before and after calling `reAlloc()` shows that it's always `0`. Debugging further, it seems like the value capacity of the `internalStruct` in the `UnionVector` always returns `0` because it has no children so [size](https://github.com/apache/arrow-java/blob/main/vector/src/main/java/org/apache/arrow/vector/complex/NonNullableStructVector.java#L373) is `0`. ``` @Override public int getValueCapacity() { return Math.min(getTypeBufferValueCapacity(), internalStruct.getValueCapacity()); } ``` **Steps to reproduce** ``` @Test public void testAppendEmptyTargetUnionVector() { final int length = 5; try (final UnionVector target = UnionVector.empty("target", allocator); final UnionVector delta = UnionVector.empty("delta", allocator)) { // populate the delta vector delta.setType(0, Types.MinorType.FLOAT4); delta.setType(1, Types.MinorType.FLOAT4); delta.setType(2, Types.MinorType.FLOAT4); delta.setType(3, Types.MinorType.FLOAT4); delta.setType(4, Types.MinorType.FLOAT4); Float4Vector deltaFloatVector = delta.getFloat4Vector(); deltaFloatVector.allocateNew(); ValueVectorDataPopulator.setVector(deltaFloatVector, 1f, 2f, 3f, 4f, 5f); assertEquals(length, deltaFloatVector.getValueCount()); delta.setValueCount(length); VectorAppender appender = new VectorAppender(target); delta.accept(appender, null); assertEquals(length, target.getValueCount()); for (int i = 0; i < length; i++) { Object floatObj = target.getObject(i); assertTrue(floatObj instanceof Float); assertEquals(i+1, ((Float) floatObj).intValue()); } } } ``` This issue does not occur if any value is set in the target vector before appending. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
