[jira] [Commented] (HIVE-18609) Results cache invalidation based on table updates

["Jason Dere (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-18609?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16418075#comment-16418075 ] 

Jason Dere commented on HIVE-18609:
-----------------------------------

Proposed changes:
- At query time, the validity of the cached result will be checked by comparing the transactional WriteIDs of the tables used in the cached query to the WriteIDs of the current query, similar to HIVE-19027. This approach only guarantees freshness if all of the tables used in the query are transactional tables. As a result, the results cache will be disabled by default for queries involving non-transactional tables.
- The above approach will only invalidate entries in the cache if that query looked up again, which could potentially leave a lot of undetected invalid entries in the cache taking up space which could cause other entries to be evicted. To remove these entries in a more timely fashion, have a background thread to periodically check the notification events for updates to the tables used in the results cache.


> Results cache invalidation based on table updates
> -------------------------------------------------
>
>                 Key: HIVE-18609
>                 URL: https://issues.apache.org/jira/browse/HIVE-18609
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Jason Dere
>            Priority: Major
>
> Look into using the materialized view invalidation mechanisms to automatically invalidate queries in the results cache if the underlying tables used in the cached queries have been modified.



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