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Posted to dev@hive.apache.org by "Namit Jain (JIRA)" <ji...@apache.org> on 2010/08/12 06:52:20 UTC
[jira] Issue Comment Edited: (HIVE-1293) Concurreny Model for Hive
[ https://issues.apache.org/jira/browse/HIVE-1293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12897577#action_12897577 ]
Namit Jain edited comment on HIVE-1293 at 8/12/10 12:51 AM:
------------------------------------------------------------
Did the cleanups and changed default value of hive.support.concurrency to false
Not sure how can we set a default value for hive.zookeeper.client.port?
Let us do the lib cleanup in a follow-up - filed https://issues.apache.org/jira/browse/HIVE-1533
was (Author: namit):
Did the cleanups and changed default value of hive.support.concurrency to false
Not sure how can we set a default value for hive.zookeeper.client.port?
Let us do the lib cleanup in a follow-up - I will file a jira
> Concurreny Model for Hive
> -------------------------
>
> Key: HIVE-1293
> URL: https://issues.apache.org/jira/browse/HIVE-1293
> Project: Hadoop Hive
> Issue Type: New Feature
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Namit Jain
> Fix For: 0.7.0
>
> Attachments: hive.1293.1.patch, hive.1293.2.patch, hive.1293.3.patch, hive.1293.4.patch, hive_leases.txt
>
>
> Concurrency model for Hive:
> Currently, hive does not provide a good concurrency model. The only guanrantee provided in case of concurrent readers and writers is that
> reader will not see partial data from the old version (before the write) and partial data from the new version (after the write).
> This has come across as a big problem, specially for background processes performing maintenance operations.
> The following possible solutions come to mind.
> 1. Locks: Acquire read/write locks - they can be acquired at the beginning of the query or the write locks can be delayed till move
> task (when the directory is actually moved). Care needs to be taken for deadlocks.
> 2. Versioning: The writer can create a new version if the current version is being read. Note that, it is not equivalent to snapshots,
> the old version can only be accessed by the current readers, and will be deleted when all of them have finished.
> Comments.
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