[jira] [Commented] (HIVE-2171) Allow custom serdes to set field comments

["Jakob Homan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-2171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13060219#comment-13060219 ] 

Jakob Homan commented on HIVE-2171:
-----------------------------------

bq. hive already stores each column's comment in StorageDescriptor. Can we get the comments from there instead of putting it to StructField?
Hive stores column information for native serdes (see [SerDeUtils.java:99|https://github.com/apache/hive/blob/trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java#L1889]).  For non-native serdes, it queries the serde's object inspector, which is what this patch is dealing with.


> Allow custom serdes to set field comments
> -----------------------------------------
>
>                 Key: HIVE-2171
>                 URL: https://issues.apache.org/jira/browse/HIVE-2171
>             Project: Hive
>          Issue Type: Improvement
>    Affects Versions: 0.7.0
>            Reporter: Jakob Homan
>            Assignee: Jakob Homan
>         Attachments: HIVE-2171.patch
>
>
> Currently, while serde implementations can set a field's name, they can't set its comment.  These are set in the metastore utils to {{(from deserializer)}}.  For those serdes that can provide meaningful comments for a field, they should be propagated to the table description.  These serde-provided comments could be prepended to "(from deserializer)" if others feel that's a meaningful distinction.  This change involves updating {{StructField}} to support a (possibly null) comment field and then propagating this change out to the myriad places {{StructField}} is thrown around.

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