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From "Daniel Dai (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-18661) CachedStore: Use metastore notification log events to update cache
Date Thu, 13 Dec 2018 22:43:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-18661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16720669#comment-16720669
] 

Daniel Dai commented on HIVE-18661:
-----------------------------------

Sorry need to take back, DDL are not usually in an open transaction, they will potentially
read old content. For example, you alter a table, then periodical update overwrite with old
image, then you do a describe, since there's no commit transaction, and there's no open transaction,
you will read old image. Is that right?

> CachedStore: Use metastore notification log events to update cache
> ------------------------------------------------------------------
>
>                 Key: HIVE-18661
>                 URL: https://issues.apache.org/jira/browse/HIVE-18661
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Metastore
>            Reporter: Vaibhav Gumashta
>            Assignee: mahesh kumar behera
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: HIVE-18661.02.patch, HIVE-18661.03.patch, HIVE-18661.04.patch, HIVE-18661.05.patch,
HIVE-18661.06.patch, HIVE-18661.07.patch, HIVE-18661.08.patch
>
>
> Currently, a background thread updates the entire cache which is pretty inefficient.
We capture the updates to metadata in NOTIFICATION_LOG table which is getting used in the
Replication work. We should have the background thread apply these notifications to incrementally
update the cache.



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