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TAJO-904: ORDER BY with a null column miss some data.#70
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It should be DROP TABLE IF EXISTS table1 PURGE. Otherwise, it will cause 'no such table error' when a developer executes this test separately.
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It works well for null first case. But, in null last case, the query results in empty rows. In my view, null last supports is not trivial and requires a bunch of codes. In contrast, the current patch looks reasonable for only null first. If there is no objection, I'll change the issue name to 'ORDER BY NULL FIRST support', and I'll create another issue for null last. |
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Hyunsik, I agree your opinion. Please go ahead |
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+1 |
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Currently Tajo ignores null value when calculates range partition range. I added a MaxValueNull flag variable in ColumnStats. If ColumnStats's max value is null, ColumnStats's max value is a non-null value and MaxValueNull flag is true. So Repartitioner calculates range cardinality with non-null value. Finally Repartitioner set null value to last range.