[jira] [Assigned] (DRILL-5021) ExternalSortBatch redundantly redefines the batch schema

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

     [ https://issues.apache.org/jira/browse/DRILL-5021?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul Rogers reassigned DRILL-5021:
----------------------------------

    Assignee:     (was: Paul Rogers)

> ExternalSortBatch redundantly redefines the batch schema
> --------------------------------------------------------
>
>                 Key: DRILL-5021
>                 URL: https://issues.apache.org/jira/browse/DRILL-5021
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.8.0
>            Reporter: Paul Rogers
>            Priority: Minor
>
> Much code in the {{ExternalSortBatch}} (ESB) deals with building vector batches and schemas. However, ESB cannot handle schema changes. The only valid schema difference is the same field path in a different position in the vector array. Given this restriction, the code can be simplified (and sped up) by exploiting the fact that all batches are required to have the same conceptual schema (same set of fields, but perhaps in different vector order) and most probably, the same physical schema (same fields and same vector order.) Note that, because of the way that the {{getValueVectorId()}} method works, each lookup of a value vector is an O\(n) operation, so that each remapping of vectors is O(n\^2).



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