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  1. Apache Drill
  2. DRILL-6307

Handle empty batches in record batch sizer correctly

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      Description

      when we get empty batch, record batch sizer calculates row width as zero. In that case, we do not do accounting and memory allocation correctly for outgoing batches. 

      For example, in merge join, for outer left join, if right side batch is empty, we still have to include the right side columns as null in outgoing batch. 

      Say first batch is empty. Then, for outgoing, we allocate empty vectors with zero capacity.  When we read the next batch with data, we will end up going through realloc loop. If we use right side row width as 0 in outgoing row width calculation, number of rows we will calculate will be higher and later when we get a non empty batch, we might exceed the memory limits. 

      One possible workaround/solution : Allocate memory based on std size for empty input batch. Use allocation width as width of the batch in number of rows calculation. 

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            • Assignee:
              ppenumarthy Padma Penumarthy
              Reporter:
              ppenumarthy Padma Penumarthy
              Reviewer:
              Paul Rogers

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