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https://issues.apache.org/jira/browse/HIVE-756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12744029#action_12744029
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He Yongqiang commented on HIVE-756:
-----------------------------------
Changes for ColumnarStruct is good.
@hive-756.patch: line 100:
The new var "prjColIDs" is not necessary. The cost wouldn't deviate too much
from using a boolean array to do the same things.
{quote}
1. Columns information is provided but empty: we ignore all columns
2. Columns information is not provided: we read all columns.
In this way if the caller (some non-hive applications) does not know the RCFile
column information settings, it can still read in all columns.
{quote}
Agree. We can use "none" as the conf value to denote empty columns, and use ""
to denote all columns. The code for setting and reading lies in
HiveFileFormatUtils.
> performance improvement for RCFile and ColumnarSerDe in Hive
> ------------------------------------------------------------
>
> Key: HIVE-756
> URL: https://issues.apache.org/jira/browse/HIVE-756
> Project: Hadoop Hive
> Issue Type: Improvement
> Reporter: Ning Zhang
> Assignee: Ning Zhang
> Attachments: hive-756.patch
>
>
> There are some easy performance improvements in the columnar storage in Hive
> I found during Hackathon.
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