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UnionMapWriter fails to write fixed size binary #586
Description
A UnionMapWriter will null out the entire map struct entry instead of setting the value to null:
childWriter.value().fixedSizeBinary().writeNull();
Actually hits NullableStructWriter#writeNull whereas UnionMapWriter should override writeNull and do a switch on the mode (though I'm not certain if null keys are valid).
EDIT:
Actually, the issue is that fixedSizeBinary needs to be overriden! Very frustrating, but this call is not overridden and is instead invoking UnionListWriter#fixedSizeBinary():
@Override
public FixedSizeBinaryWriter fixedSizeBinary() {
return this;
}The real impl needs to override like so:
@Override
public FixedSizeBinaryWriter fixedSizeBinary() {
switch (mode) {
case KEY:
return entryWriter.fixedSizeBinary(MapVector.KEY_NAME);
case VALUE:
return entryWriter.fixedSizeBinary(MapVector.VALUE_NAME);
default:
return this;
}
}
Activity
[-]UnionMapWriter fails to write null values[/-][+]UnionMapWriter fails to write fixed size binary[/+]jbonofre commentedon Feb 12, 2025
Let me try to reproduce the issue on a test (and fix it).
mihazagar commentedon Apr 27, 2025
@jbonofre , I’d like to tackle this issue!
Please let me know if there are any details you’d like me to keep in mind.
apacheGH-586: Override fixedSizeBinary method for UnionMapWriter
apacheGH-586: Implement a separate unit test for FixedSizeBinaryWriter
apacheGH-586: Implement a separate unit test for FixedSizeBinaryWriter
apacheGH-586: Introduce fixedSizeBinary(int byteWidth) + fix test
apacheGH-586: Use only maps in the testFixedSizeBinaryWriter
apacheGH-586: Use only maps in the testFixedSizeBinaryWriter
apacheGH-586: Add unit test for first time key and value initialization
apacheGH-586: Override fixedSizeBinary method for UnionMapWriter (apa…