[jira] [Updated] (DRILL-6307) Handle empty batches in record batch sizer correctly

["Padma Penumarthy (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-6307?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Padma Penumarthy updated DRILL-6307:
------------------------------------
    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. We have to allocate memory for those vectors correctly. We also have to include row width of those columns in the outgoing row width and number of rows calculation. 

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.

 

  was:
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. We have to allocate memory for those vectors correctly. We also have to include row width of those columns in the outgoing row width and number of rows calculation. 


> Handle empty batches in record batch sizer correctly
> ----------------------------------------------------
>
>                 Key: DRILL-6307
>                 URL: https://issues.apache.org/jira/browse/DRILL-6307
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Flow
>    Affects Versions: 1.13.0
>            Reporter: Padma Penumarthy
>            Assignee: Padma Penumarthy
>            Priority: Major
>             Fix For: 1.14.0
>
>
> 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. We have to allocate memory for those vectors correctly. We also have to include row width of those columns in the outgoing row width and number of rows calculation. 
> 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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