[
https://issues.apache.org/jira/browse/HIVE-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12760312#action_12760312
]
Schubert Zhang commented on HIVE-493:
-------------------------------------
@Prasad,
1) We want the data to be available in the Hive table after each run of the
MapReduce job. Do you mean we should only 'add partition' once at the first
time? and need not do it after add new files into a existing partition?
2) Thanks for your good advices. The lease is necessary.
It seems we (you and we) should add more features into Hive and let Hive to be
a data server (or data warehouse server), since current Hive is a dumb data
tool to translate HQL to MapReduce.
When thinking of following important data service features, such as:
- Indexing
- Compact
- Lease
- Real Dyanmic Partition (or automatic partition ,even varying partition)
- ....
It seems, besides MapReduce data processing and SQL, we shall implement a light
and flexiable BigTable/HBase like data service solution.
> automatically infer existing partitions of table from HDFS files.
> -----------------------------------------------------------------
>
> Key: HIVE-493
> URL: https://issues.apache.org/jira/browse/HIVE-493
> Project: Hadoop Hive
> Issue Type: New Feature
> Components: Metastore, Query Processor
> Affects Versions: 0.3.0, 0.3.1, 0.4.0
> Reporter: Prasad Chakka
>
> Initially partition list for a table is inferred from HDFS directory
> structure instead of looking into metastore (partitions are created using
> 'alter table ... add partition'). but this automatic inferring was removed to
> favor the later approach during checking-in metastore checker feature and
> also to facilitate external partitions.
> Joydeep and Frederick mentioned that it would simple for users to create the
> HDFS directory and let Hive infer rather than explicitly add a partition. But
> doing that raises following...
> 1) External partitions -- so we have to mix both approaches and partition
> list is merged list of inferred partitions and registered partitions. and
> duplicates have to be resolved.
> 2) Partition level schemas can't supported. Which schema to chose for the
> inferred partitions? the table schema when the inferred partition is created
> or the latest tale schema? how do we know the table schema when the inferred
> partitions is created?
> 3) If partitions have to be registered the partitions can be disabled without
> actually deleting the data. this feature is not supported and may not be that
> useful but nevertheless this can't be supported with inferred partitions
> 4) Indexes are being added. So if partitions are not registered then indexes
> for such partitions can not be maintained automatically.
> I would like to know what is the general thinking about this among users of
> Hive. If inferred partitions are preferred then can we live with restricted
> functionality that this imposes?
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
