[jira] [Created] (DRILL-5598) AllocationHelper.allocateNew ignores maps, arrays

["Paul Rogers (JIRA)" <ji...@apache.org>]

Paul Rogers created DRILL-5598:
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             Summary: AllocationHelper.allocateNew ignores maps, arrays
                 Key: DRILL-5598
                 URL: https://issues.apache.org/jira/browse/DRILL-5598
             Project: Apache Drill
          Issue Type: Bug
    Affects Versions: 1.10.0
            Reporter: Paul Rogers
            Assignee: Paul Rogers
             Fix For: 1.11.0


The method {{VectorAccessibleUtilities.allocateVectors()}} is used to allocate vectors when the external sort creates a spill batch. (Along with various other places.)

This method does not allocate space for repeated vectors or vectors contained in maps, resulting in vectors starting life with a very short size. This cases repeated doublings as data is loaded into the vectors:

{code}
BigIntVector - Reallocating vector [$data$(BIGINT:REQUIRED)]. # of bytes: [32768] -> [65536]
UInt4Vector - Reallocating vector [$offsets$(UINT4:REQUIRED)]. # of bytes: [16384] -> [32768]
UInt4Vector - Reallocating vector [$offsets$(UINT4:REQUIRED)]. # of bytes: [16384] -> [32768]
UInt1Vector - Reallocating vector [$bits$(UINT1:REQUIRED)]. # of bytes: [4096] -> [8192]
...
{code}

Maps can be handled by iterating over the contained vectors. Arrays and VarChars are harder as the code needs some hint about data size. We have hard-coded hints available (the assumption that VarChar columns are 50 characters wide, and that arrays have 10 elements.) Better would be to pass in metadata about sizes extracted from previously-seen batches in the same operator that allocates a new batch.



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