[jira] [Commented] (DRILL-335) Implement hash aggregation operator for grouped aggregation

["Aman Sinha (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13921911#comment-13921911 ] 

Aman Sinha commented on DRILL-335:
----------------------------------

An updated patch which contains the cumulative changes was posted to reviewboard.  This second patch contains following enhancements/fixes: 
1. It includes support for the code generation of the probe side of a hash join (previously, we only needed the 'build' side for the hash aggregate)
2. Fix for a index out of bound error that I encountered while doing testing - this was related to using the wrong TypedFieldId when accessing the hash table's container. This is resolved by doing the creation of htContainer as part of ChainedHashTable and making a clone of it in HashTableTemplate. 
3. Address a review comment: Allocate the links, hashValues and startIndices using our vector allocators (off-heap) instead of on the heap. 

> Implement hash aggregation operator for grouped aggregation
> -----------------------------------------------------------
>
>                 Key: DRILL-335
>                 URL: https://issues.apache.org/jira/browse/DRILL-335
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Aman Sinha
>            Assignee: Aman Sinha
>         Attachments: Drill-335-1.patch, Drill-335-2.patch, DrillAggrs.pdf
>
>
> Placeholder for doing design and implementation of hash based aggregation in Drill.  Currently, it supports sort based aggregation.   Hash aggregation involves building a hash table on the grouping columns and maintaining workspace for each of the aggregate functions in the query.  This issue will focus on non-distinct aggregation for now (i.e aggregate function does not contain DISTINCT).  A separate issue will be created to track distinct aggregation. 



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